（財）
日産科学振興財団／奈良先端科学技術大学院大学

主催─Organiser : Nissan Science Foundation / Nara Institute of Science and Technology

2月26日（木）9:30am～5:30pm

平成21年

日時─

［問い合わせ先］株式会社クバプロ〒 102-0072 千代田区飯田橋 3-11-15 UEDA ビル 6 階TEL：03-3238-1689 FAX：03-3238-1837
E-mail：symposium@kuba.jp

Date : 9:30am-5:30pm, Thursday, 26th February, 2009

科学技術館 サイエンスホール

会場─

Venue : Science Hall, Science Museum, Tokyo

NISSAN SCIENCE FOUNDATION
Woody Plants Biotechnology Symposium
Thursday, 26th February, 2009
Science Hall in the Science Museum, Tokyo

The success in sequencing of the Arabidopsis whole genome in 2000 has invited crop andplant sciences into a new era that provides us with new concepts in biology and new biotechnology that were not reached with the previous single-gene sciences. The new era is opened inresearches in gene functions in many crops, wild plants and woody plants, the genome of whichhave not been sequenced, rice genome decoding and molecular-based breeding of rice, andtransformation of genes into important crops from organisms phylogenetically far from thecrops. Plant biotechnology is now not restricted to experimental model plants, but has been
extended to feedstock-producing woody plants, such as eucalyptus, gum trees and Jatropha.
During the great advances in plant sciences in the last decade, the first success in decoding thewhole genome of poplar is surely providing the next decade with information that could not becovered by genome information from model annual plants and will contribute to future biotechnology with woody plants.
The Nissan Science Foundation, NSF, has financially supported researchers working in
the fields of environmental sciences. The field of sequestration of environmental CO2 with aid
of solar energy is highlighted and emphasized. The Yokota laboratory of NAIST is engaged in
the project research, entitled “Strengthening of the Carbon Dioxide-Adsorbing Capacity of
Woody Plants by Improving Their Stress Responses”, as a special research project supportedby the Foundation.
This Symposium is organized by the laboratory, as part of the project research, to discuss
the present and future of plant science and biotechnology of woody plants with invited, distinguished scientists in the fields of genome sciences, biotechnology, and physiology and ecologyof these plants.
I hope a successful conclusion of this Symposium in our scientific contribution to construction of the sustainable world.

Nissan Science Foundation (NSF)
Woody Plants Biotechnology Symposium
Chair: Akiho Yokota

─1─

NISSAN SCIENCE FOUNDATION
Woody Plants Biotechnology Symposium

ProgramPosters
P-1

Nitration of peripheral proteins of photosystem II by atmospheric nitrogen dioxide suppresses
oxygen evolution in plants

9:30- 9:40

1

1

2

1

1

M. Takahashi , J. Shigeto , K. Asada , A. Sakamoto and H. Morikawa

Opening Remarks

1

9:40-10:10

P-2

Plenary Lecture

Invited Speakers in Genomics and Molecular Session
Chaired by Dr. S. G. Maphanyane (Dept. Agric. Res., Botswana)

RIKEN Plant Science Center

P-3

1

Lunch and Poster Session

13:40-15:10

Invited Speakers in Biotechnology
Chaired by Dr. S. Suharsono (Res. Inst. Biores. Biotechnol., Indonesia)

Forest. Res. Inst., Oji Paper Company Ltd.

P-4

H. Ishii
Grad. Sch. Agric., Kobe Univ.

Invited Speakers in New Directions in Wood Biotechnology
Chaired by Dr. E. Peloewetse (Dept. Biol., Univ. Botswana)
D. Kramer (Washington State University at Pullman)
Why is Natural Photosynthesis so Inefficiency? How to Cope with Excess Solar Energy in
Woods

Depart. Chem. Biosci., Fac. Sci., Kagoshima Univ.

P-6

Functional analysis of nuclear-genes for chloroplast development using albino mutantsin Arabidopsis
1

1

1

1

1

2

3

F. Myouga , N. Nagata and K. Shinozaki
1

2

2

3

Shizuoka University, RIKEN Plant Science Center, Japan Women’s University

pfkB-type carbohydrate kinase family protein, NARA5, is essential for the massive expressions ofplastid-encoded photosynthetic genes in Arabidopsis thaliana
1

1

2

1

T. Ogawa , K. Nishimura , K. Tomizawa , H. Ashida and A. Yokota
1

2

P-8

A DEAD-box RNA Helicase RH39 Is Required for Chloroplast 23S rRNA Processing and Essential
for Plant Development in Arabidopsis thaliana
K. Nishimura, T. Ogawa, H. Ashida and A. Yokota
Grad. Sch. Biol. Sci., Nara Inst. Sci. Technol.

P-9

The long-term responses of the photosynthetic proton circuit to drought
1

2

1

1

2

Inst. Biol. Chem., Washington State Univ., Pullman

E. Abe (Nissan Science Foundation)

─2─

1

1

2

K. Kohzuma , J. A. Cruz , K. Akashi , S. Hoshiyasu , Y. Munekage , A. Yokota and D. M. Kramer
Grad. Sch. Biol. Sci., Nara Inst. Sci. Technol.

Closing Remarks

1

Grad. Sch. Biol. Sci., Nara Inst. Sci. Technol., RITE

1

17:20-17:30

1

R. Motohashi , T. Kato , M. Hara , K. Matsuura , S. Itayama , Y. Akaike ,K. Akashi (Nara Institute of Science and Technology)
Wild plant resources for studying environmental stress tolerance and plant productivity
K. Hikosaka (Tohoku University)
Interspecific variations in photosynthetic capacity: what is different between trees andherbs?

Genetic transformation of the symbiotic nitrogen-fixing bacterium Frankia
K. Kucho, K. Kakoi, M. Yamaura, S. Higashi, T. Uchiumi, and M. Abe

P-7

15:40-17:20

Tree Physiology Research for Increasing the Carbon Sequestration and Photosynthetic Capacityof Forest Ecosystems

T. Hayashi (Kyoto University)
Loosening xyloglucan accelerates the enzymatic hydrolysis of cellulose in wood
Coffee Break and Poster Session

1

Lab. Plant Environ. Resp., Grad. Sch. of Agric. Sci., Tohoku Univ.

T. Kawazu (Oji Paper Co., Ltd.)
Eucalyptus Tree Breeding for Improving Productivity in Acid-soil Areas

15:10-15:40

2

2

P-5

K. Shinohara (Forestry and Forest Product Research Institute)
Development of Genetically Modified Trees in Japan

2

1

T. Demura (RIKEN Plant Science Center)
Molecular Mechanism of Cellulosic Biomass Production
11:50-13:40

Changes in Rubisco content during leaf development in Eucalyptus globulus
Y. Suzuki , T. Kihara-Doi , T. Kawazu and A. Makino

C. Douglas (University of British Columbia, Vancouver)
The P o p u l u s Genome: Towards Understanding the Regulation of Secondary Wall
Formation and Optimization of Biofuels Traits
D. Shibata (Kazusa DNA Research Institute)
Omics approches for industrial uses of woody plants

Analysis of regulatory mechanisms of plant growth in response to light environments
T. SakaiA. Shinmyo (Emeritus Professor, Nara Institute of Science and Technology)
Plants save Future of People and Earth
10:10-11:50

2

Depart. Math. & Life Sci., Grad. Sch. Sci., Hiroshima Univ., Fac. Engin., Fukuyama Univ.

A. Yokota (Nara Institute of Science and Technology)

─3─

P-10 Energy conversion efficiency by Photosystem II assembled with variant copies of subunit D1 inthemophilic cyanobacterium Themosynechococcus elongatus
1

2

M. Sugiura , F. Rappaport and A. Boussac

31

Cell-Free Science and Technology Research Center, Ehime University

2

Institut de Biologie Physico-Chimique, CNRS

3

iBiTec-S, CEA Saclay

P-11 Probing photosynthesis in the living plant: What can we learn about the limits of photosyntheticenergy conversion efficiency?
D. M. Kramer
Inst. Biol. Chem., Washington State Univ., Pullman

Overseas invitees: 30-min talk and 10-min discussion
Japanese invitees: 25-min talk and 5-min discussion

─4─

Plants save Future of People and Earth

Atsuhiko Shinmyo
Emeritus Professor, Nara Institute of Science and Technology, Japanth

In the 20 century, the world population increased from 1.6 billion to 6 billion as a result of a drastic
increase of food production established by using huge amount of petroleum. Present agricultural productionin the developed countries is supported by high energy consuming cultivation, such as agricultural machines
and implement, irrigation, chemical fertilizer, and chemical herbicides and insecticides. Petroleum brought
not only pleasant and convenient life in the developed countries, but also life of 300 - 400 million peoples in acold district, such as Hokkaido, Canada, northern USA and northern Europe.
It is estimated that the world population of 6.7 billion in 2008 will reach to 9 billion. Is it truth?
Petroleum will be exhausted within 40 years. Increase of food production to support 9 billion populations
without petroleum will be very difficult. Program of the exchange of gasoline and diesel oil to biofuel, such as
ethanol and biodiesel from sucrose, starch and rape seed, suppresses the food supply. Although biofuel production will be changed from biomass competing to foods and feeds to unused cellulosic materials, an efficient conversion of lingo-cellulose to biofuel have to overcome high technological barrier.
It is said that the Japanese forest 100 year ago was very poor, since peoples used woods as fuel, but it
has been recovered after start to use petroleum as fuel. Russia stopped to send the natural gas to the
Ukraine on Jan. 10, 2009 and it affected the supply to Europe also. TV reported that many European peoples
used the woods to survive in the cold winter. The best solution to overcome the shortage of petroleum might
be increase of production of plant biomass including cereals, root vegetables, oil plants, and woods.
Annual production of plant biomass energy is 10 times of the present use, of which almost 90% is fossil
resources. Plant productivity is significantly suppressed by a lot of environmental stresses. Stress-resistantgenes can recover the reduction of plant productivity by using recombinant DNA technology. It is possible toincrease the maximum productivity genetically determined. There are huge areas unsuitable for agriculturein the world, such as acidic and alkaline soil, salty and dry land, cold and hot weather. Growth of plants inthese areas will be possible by the progress of plant molecular biology and biotechnology.

─7─The Populus Genome: Towards Understanding the Regulation ofSecondary Wall Formation and Optimization of Biofuels Traits

Carl J. Douglas
Department of Botany, University of British Columbia, Vancouver, BC, Canada

Poplars and aspens (Populus) have potential as north-temperate biofuels feedstocks, and possess cellwall biochemistries that are relatively readily converted to fermentable sugars for bioethanol production.
Northwestern North America including British Columbia (BC) has a huge genetic diversity in its native
Populus species, and a focus on Populus genetic variants deployed in plantations has many advantages.
Despite this potential, many hurdles must be overcome if a Populus-based bioenergy sector is to become areality. A major challenge will be to achieve rapid genetic improvement and domestication of poplars withrespect to biofuels and biomass traits. The draft genome of Populus trichocarpa (Nisqually-1 genotype) was
first released in 2005 and published in 2006. This genome resource has opened the door both to a better
understanding of the regulation of wood and secondary wall formation, and to rapid genetic improvement ofPopulus for biofuels applications. We and our collaborators are taking a two-pronged approach towards thisgoal. First, we are using genomics and comparative genomics to better understand the genes that control
secondary cell wall biosynthesis and its regulation. This will help to inform candidate genes that may affectsecondary cell traits, and examples of these will be discussed. Secondly, we are targeting the discovery
genetic variation, predominantly singe nucleotide polymorphisms (SNPs), in a large suite of such poplar candidate genes, in order test the association of allelic variation in such genes to biofuels and biomass related
phenotypes. To achieve the latter goal, we are using a collection of 500 wild P. trichocarpa genotypes fromBC and the adjacent states of Oregon and Washington, replicated in field trials, to generate a SNP polymorphism database for 7000 candidate genes. In parallel, we will generate wood chemistry and adaptive trait phenotypes for the same genotypes. This will culminate in the determining the SNP genotypes for at least 600
candidate genes in 500 individuals, to test for genotype-phenotype associations. Our initial experiments are
aimed at SNP discovery by transcriptome resequencing, using next generation sequencing and the P. trichocarpa Nisqually-1 genome sequence as a reference. Initially, eight P. trichocarpa individuals from a common population but spanning a geographic range of 54°N to 49°N were selected for xylem transcriptome
resequencing. Initial resequencing results from this first set of individuals will be discussed.

─9─

Omics approaches for industrial uses of woody plants

Daisuke Shibata
Kazusa DNA Research Institute, Kazusa-Kamatari 2-6-7, Kisarazu 292-0818, Japan

With a wealth of cDNA and genomic sequences of various plant species including woody plants, my lab
has been working on omics technologies, especially those in metabolomics for plant biotechnology. One of
the major drawbacks in metabolomics is the difficulty of identifying metabolites in a high-through-put, nontargeted manner. Thus, we introduced a liquid chromatography-coupled Fourier transform ion cyclotron resonance mass spectrometer (LC-FT/ICR-MS) to analyze metabolites with a high mass accuracy of 0.5 ppm.
Such ultra-high accuracy allows us to predict a molecular formula or possible formulas of a metabolite, andfurthermore, the MS/MS fragmentation patter of the metabolite produced from the machine provides a cue to
speculate the chemical structure. We are challenging toward a comprehensive annotation of metabolites invarious organisms, including diverse plant species including woody plants, microorganisms and animals,
which will provide a firm basis to the metabolomics research. For example, over 800 tomato metabolites
including many novel ones were annotated (Iijima et al., Plant J. 54, 949-962, 2008). However, the annotation
process was very time-consuming. Even for well-trained chemists, a working period of at least three months(!!) to a single tomato sample was needed to process the whole chromatography dataset. Thus, we developed
the pipeline PowerFT to mimic the annotation processes in a computational way, where the whole processesof peak detection, isotope peak identification, formula prediction and web-information search were automatedwithin 30 minutes. We also prepared another pipeline, PowerMatch, to compare the processed data sets on agraphical interface. To accommodate the curated metabolite datasets, we are now constructing the database"KOMICS" (Kazusa OMICS, http://webs2.kazusa.or.jp/komics/).
To integrate quantitative datasets of transcripts and metabolites on metabolic maps, we developed agraphical interface KaPPA-View (Tokimatsu et al., Plant Physiology 138, 1289-1300, 2005, http://kpv.kazusa.or.jp/
kappa-view3/). Some examples of application of our technologies to woody plants will be presented.
This work was partly supported by the Kazusa DNA Research Foundation and New Energy andIndustrial Technology Development Organization (NEDO) as part of a project called “Development ofFundamental Technology for Controlling the Material Production Process of Plants”.

─ 11 ─

Molecular Mechanism of Cellulosic Biomass Production

Taku Demura
RIKEN Plant Science Center, Yokohama 230-0045, Japan

Cellulosic biomass, composed mainly of cellulose, hemicellulose, and lignin, is an attractive renewableenergy feedstock to be converted into biofuels such as bioethanol. Since the plant secondary cell walls produced in wood and xylem are the major sources of cellulosic biomass, it is extremely important to unravel themechanisms of plant cell wall formation. We have been studying regulatory mechanisms of secondary cellwall formation using model cell culture systems in Zinnia elegans and Arabidopsis thaliana in combination
with the comprehensive gene expression profiling and the reverse genetic analysis of candidate genes controlling secondary cell wall formation. Our efforts resulted in the identification of a number of important regulatory genes including several NAC-domain and MYB-related transcription factors.
Arabidopsis VASCULAR-RELATED NAC-DOMAIN6 (VND6) and VND7, encoding NAC-domain transcription factors, can induce secondary cell wall formation of xylem vessels, not only in Arabidopsis plants but
also in tobacco BY-2 cultured cells, while the loss of function, by overexpression of dominant suppressor
forms of VND6 and VND7, inhibits secondary cell wall formation of vessels. Further characterization of
VND6 and VND7 and closely related proteins (VND1 to VND5) revealed that the VND proteins cooperatively regulate secondary cell wall formation. We recently found that another NAC-domain transcription factor(VNI2) interacting with VND7 negatively regulates VND7 function. In addition, several R2R3-Myb transcription factors that are expressed specifically in xylem vessels and fibers are found to regulate secondary cellwall formation, of which Arabidopsis MYB46 and MYB83 were shown to function redundantly in secondarycell wall formation in vessels. Based on the results we have recently started reverse genetic analysis ofthese genes in trees. Overexpression of Arabidopsis VND6 and VND7 in poplar resulted in the ectopic formation of secondary cell walls in leaves. In contrast, overexpression of dominant suppressor forms of VND6 and
VND7 inhibited secondary wall formation of xylem cells to some extent, suggesting that VND6 and VND7
function as positive regulators of secondary cell wall formation in tree species.

─ 13 ─Development of Genetically Modified Trees in Japan

Kenji Shinohara
Department of Molecular and Cell Biology,
Forestry and Forest Products Research Institute (FFPRI), JapanThe nucleotide sequence of the entire genome of black cottonwood, Populus trichocarpa, was determined in 2006, and at present two research groups in Japan and US is determining that of Eucalyptus.
However, it is quite difficult to study the structural genomics of Cryptomeria japonica D. Don because of its
large genome. The FFPRI has succeeded in the large-scale collection of 19,841 nonredundant P. nigra fulllength enriched cDNA clones by collaboration with the RIKEN Plant Science Center. Population of thesecDNA clones represents approximately 44% of the predicted genes in the Populus genome. And the FFPRI
has also collected 10,464 nonredundant full-length enriched cDNA clones of C. japonica male strobili. Fulllength cDNA resources are extremely useful, not only for gene annotation and the determination of transcriptional start sites, but also for functional analyses. These will be valuable tools to provide further insight
into the genomics of woody plants and transcriptome.
Genetically modified trees are available for the prevention of global warming. I am interested in thegrowth control of woody plants by genetic engineering with the above cDNA resources. It is possible togenetically engineer trees that grow faster and produce more biomass than the wild type, simply by thedown-regulation or the constitutive expression of genes for the biosynthesis of ethylene or gibberellin. One
cDNA clone encoding the poplar terminal flower 1 ortholog that acts as a repressor of flowering in vegetative
tissues has also been isolated. An early flowering variety of transgenic poplar was generated by the downregulation of the gene. However, the growth of transgenic poplar was drastically inhibited. Therefore, thesuppression of flowering will lead to the enhanced productivity. I also introduce the improvement in environmental stress tolerance by genetic engineering in Japan. There are several stress-tolerant transgenic trees,such as the drought-tolerant eucalyptuses and acid-tolerant eucalyptuses by the Oji Paper Co., Ltd., the salttolerant eucalyptuses by the Nippon Paper Group, Inc. and the ozone-tolerant poplars by the FFPRI. I will discuss the availability of genetically modified trees for the prevention of global warming.

─ 15 ─

Eucalyptus Tree Breeding for Improving Productivity
in Acid-soil Areas

Tetsu Kawazu
Forestry Research Institute, Oji Paper Co., Ltd., Japan
Contact: tetsu-kawazu@ojipaper.co.jp

In the pulp and paper industry, raw material and fuel costs are rising and competition is intensifying. As
a result, the importance of a resource strategy targeting the stabilization of raw material procurement grows
each year. In particular, wood chips are expected to be in short supply worldwide, and Japanese paper-manufacturing companies make efforts to forest overseas. However, overseas forestation faces difficulties inprocuring sites for forestation. In addition, due to the global shortage of grain, there is competition for theuse of land with agriculture. Under these circumstances, forestation using trees with high growth performance and high wood quality is important. Or else, forestation will expand to the fields with serious environmental problems. Therefore, it is important to produce trees with tolerance to environmental stress such as
phytotoxicity in rhizosphere, drought, and poor nutrition by conventional and molecular breeding technology.
Acid soils that limit plant growth are found throughout the world and cover 30-40% of the world’s arable
soils. A lot of factors contribute to acid soil toxicity depending on soil composition. The primary factor limiting plant growth is aluminum (Al) toxicity. For most plants, exposure to Al causes severe inhibition of root
growth. And plants in acid soils also suffer from deficiencies of phosphorus, nitrogen, calcium, magnesium
and potassium. The resulting restricted root system has trouble in nutrient and water uptake, making theplants more susceptible to drought stress (Samac and Tesfaye 2003). An effective approach managing acidsoils is the application of lime. However, large-scale liming is not practical in forestry due to the costs. In
such areas, Al-tolerant (acid soil tolerant) plants are being developed through selection and breeding.
Although the exact mechanisms of acid soil tolerance have not been clearly defined yet, intense research
efforts have succeeded in identifying the major mechanism of Al-tolerance. Excretion of organic acid, especially citric acid, from roots is an efficient acid soil-tolerant mechanism (Ma et al. 2001). There are several
successful reports that the modification of citric acid metabolism by the gene manipulation in herbaceous
plants could improve plant growth on acid soils probably due to enhancement of tolerance to Al toxicity andacquisition of phosphate from insoluble phosphate compounds (Koyama et al. 2000).
Eucalyptus is the most widely planted hardwood tree in the tropical and subtropical areas because of its
superior growth, broad adaptability and multipurpose wood properties. To apply the molecular breeding technology to Eucalyptus breeding, we developed a unique transformation system of Eucalyptus trees using shootprimordium formation (Kawazu et al. 2003). We have produced hybrid Eucalyptus (Eucalyptus grandis x E.
urophylla) transgenic plants with overexpression of mitochondrial citrate synthase (CS) gene isolated fromcarrot or stable knock-down of NADP-isocitrate dehydrogenase (ICDH) by the RNAi technique. Both transgenic lines showed increased citrate accumulation and enhancement of citrate excretion from the roots,
which showed improved growth on acid soil in greenhouses.

Results and Discussion
Eucalyptus was transformed with the full length CS cDNA from carrot (Takita et al. 1999) or the RNAi
cassette using 3’-UTR of ICDH from Eucalyptus. These genes were controlled by CaMV 35S promoter. We
selected two lines each for both transformants by the assay of the enzyme activity. Activities of otherenzymes related to citrate metabolism in transformants were almost the same as those of the host─ 17 ─

Eucalyptus line. These transgenic lines with higher CS activity or lower ICDH activity increased citrate concentration in roots and enhanced their ability of citrate excretion from roots compared with the host line.

Loosening xyloglucan accelerates the enzymatic hydrolysis
of cellulose in wood

Citrate excretion level of transgenics was 1.5-1.7 times higher than that of the host line.
When grown on Japanese acid soil (Andisols), CS-overexpressed Eucalyptus line improved its growth,
especially root growth, compared with that of the host line. Also, the transgenic line with repressed ICDH
expression showed improved growth on the Japanese acid soil, too.
These results indicate that the modification of citric acid metabolism to accumulate more citrate by genemanipulation, i.e. overexpression of CS and/or repression of ICDH is a useful approach to enhance citrate

Takahisa Hayashi, Rumi Kaida, Tomomi Kaku and Kei’ichi Baba
Kyoto University, RISH, Gokasho, Uji, Kyoto 611-0011, Japan

excretion from the roots and in turn improve plant growth on acid soils. However, transgenic tobacco plants
with overexpressed CS or repressed ICDH did not show significant increase of citrate concentration in tissue
and citrate release, and did not enhance its Al tolerance (Delhaize et al. 2003). Therefore, the effect of theseapproaches might depend on the plant species. In order to evaluate growth performance of transgenic eucalypts on acid soil of the Brazilian commercial plantation, cultivation test of transgenic eucalypts overexpressing CS was conducted. In this experiment, micro-grafted transgenic eucalypts (grafted non-transgenic euca-

Cellulase does not easily hydrolyze 1,4-β-glucan intercalated with hemicellulose nor does hemicellulase

lypts on transgenic roots) showed higher response in P accumulation and greater primary growth under theefficiently attack hemicellulose intercalated tightly into microfibrils in the xylem because plant cell elonga-

condition of lower P availability than controls.

tion and expansion further tighten the intercalation between 1,4-β-glucans and hemicellulose during growth.

Genetic modification of citrate metabolism in eucalypts has some ameliorating effects on enhancing tol-

The question at the xylem is whether the hydrolysis of cellulose could be enhanced by the prevention of

erance to acid soil. For further improvement of citrate excretion ability in transgenic plants, it would be need-hemicellulose association with its constitutive degradation during growth. Our aim was to assess the interca-

ed to co-regulate the ability of citrate transport on plasmamembrane. One of important proteins in citratelation of hemicellulose as a recalcitrance of cell walls to saccharification. Here, we produced several trans-

efflux is a citrate transporter. Recently, a citrate transporter gene was isolated from barley (Furukawa et al.

genic poplars overexpressing xyloglucanase, cellulase, xylanase, galactanase and polygalacturonase, in hopes2007). In the report, introduction of the citrate transporter gene enhanced citrate excretion by four-fold com-of creating useful plants for the production of biofuels. The saccharification and fermentation was higher inpared with that of control plants and conferred Al tolerance to tobacco. On the basis of this idea, we are pro-the xylem overexpressing xyloglucanase, cellulase and xylanase than in that of the wild-type plant.

moting the isolation of transporter genes and associated genes from eucalypts. Moreover, we would like toTreatment with ultrasonication allowed solubilization of xyloglucan and xylan from the xylem of the wild-type

put such transgenic eucalypts to practical use. We have to consider the diffusion of transgenes to environ-poplar and enhanced its saccharification. These results show that the elimination of xyloglucan and xylan pro-ment by pollen. In this project, micro-grafting was employed and was recognized to be one of effective ways.

motes saccharification of cellulose microfibrils and leads to an increased ethanol productivity. This is proba-

For a general system to prevent the diffusion of pollen, we have tried the development of non-flowering

bly because the amorphous regions of cellulose microfibrils are intercalated and cross-linked with each othermutants by the heavy ion beam irradiation.

by these two polysaccharides.

Acknowledgment
This research was partially supported by the Ministry of Economy, Trade and Industry of Japan.

References
Delhaize, E., Ryan, P.R., Hocking, P.J. & Richardson, A.E. (2003) Plant Soil, 248: 137-144.
Furukawa, J., Yamaji, N., Wang, H., Mitani, N., Murata, Y., Sato, K., Katsuhara, M., Takeda, K. & Ma, J.F. (2007) Plant Cell
Physiol. 48: 1081-1091.
Kawazu, T., Doi, K. & Kondo, K. (2003) US Patent 6,563,024.
Koyama, H., Kawamura, A., Kihara, T., Hara, T., Takita, E. & Shibata, D. (2000) Plant Cell Physiol. 41: 1030-1037.
Ma, J.F., Ryan, P.R. & Delhaize, E. (2001) Trends Plant Sci. 6: 273-278.
Samac, D.A. & Tesfaye, M. (2003) Plant Cell, Tissue and Organ Culture 75: 189-207.
Takita, E., Koyama, H., Shirano, Y., Shibata, D. & Hara, T. (1999) Soil Sci. Plant Nutr. 45, 197-205.

─ 18 ─

─ 19 ─

Why is Natural Photosynthesis so Inefficiency?
How to Cope with Excess Solar Energy in Woods

David M. Kramer
Institute of Biological Chemistry. Washington State University, Pullman, WA 99164, USA

This talk will focus on why photosynthesis is not as efficient as is theoretically possible, and what, if
anything, we can do about it. These issues are critical for efforts to improve photosynthesis for food production, biofuels production and carbon sequestration. I will argue that natural photosynthesis did not evolve asa maximally efficient energy storage system, nor to make biofuels, but instead evolved as an add-on module
to life, allowing organisms to tap into a huge new power source, solar energy, and thus to colonize and survive in new environments far from geochemical energy sources. Photosynthesis is thus limited by what I
call ‘legacy biochemistry’, and under the conditions that really matter for bioenergy, plants are overpoweredby solar energy. Regulating this energy is critical for avoiding deleterious side reactions (photodamage).
Consequently, natural photosynthesis is ‘tuned’ both by the requirements of sustaining, while not hindering,
the processes of life. To improve photosynthetic efficiency, it is essential to understand how the light reactions are integrated into the rest of plant biochemistry. The talk will cover areas where integration is finely
tuned in surprising ways, with important lessons for potential engineering efforts.

─ 21 ─

Wild plant resources for studying environmental stress tolerance
and plant productivity

Kinya Akashi
Graduate School of Biological Sciences, Nara Institute of Science and Technology (NAIST),
Ikoma, Nara, 630-0192, Japane-mail: akashi@bs.naist.jp

Earth’s land accommodates estimated ~250,000 terrestrial plant species, which are extremely diversified in their life form, morphology and physiology. Distribution of the diversified plants in various ecologicalniches must have been accompanied with their effective acclimation mechanisms to the habitats. Water
deficits are recognized as the prime factor limiting vegetative growth and ecological distribution of terrestrial
plants. Although a small group of plants termed xerophytes are unique for their tolerance to drought in thepresence of strong light, little has been known for the molecular mechanisms underlying their successful
adaptation to the arid environments. Wild watermelon (Citrullus lanatus) is a C3 xerophyte native to the
Kalahari Desert, and has been studied as the model xerophyte to understand how C3 plants can survive underharsh environmental stresses. A number of desirable physiological traits have been recognized in this plant,such as vigorous root growth under drought, maintenance of leaf water status and tolerance to excess light
conditions. Transcriptome and proteome analyses have highlighted many useful genes, proteins and metabolites, which offer a wide range of possibilities for improving environmental stress tolerance and biomass productivity of other plants through molecular breeding. A promising target for the breeding program is
Jatropha curcus, which efficiently produces oil-rich seeds suitable for biodiesel, and possesses great potentials for biofuel production in semi-arid areas in the world. We launched the research and development program for Jatropha through the international consortium, which aims at genetic improvement and field experiments of this plant in Southeast Asia and African continent. The perspectives and current status of this project is also presented in this talk.

─ 23 ─

Interspecific variations in photosynthetic capacity :what is different between trees and herbs?

Kouki Hikosaka
Tohoku University, Japanhikosaka@mail.tains.tohoku.ac.jp

Photosynthetic capacity is known to vary considerably among species. It is well known that woody
species tend to have lower photosynthetic capacity than herbaceous species. Its physiological cause and ecological significance have been one of the most fundamental questions in plant ecophysiology. Photosynthetic
nitrogen-use efficiency (PNUE, photosynthetic rate per unit leaf nitrogen) has attracted much attention tounderstand the inherent variation in photosynthetic capacity among species. Previous studies have demonstrated that leaf nitrogen is less allocated to Rubisco in low-PNUE species. It was considered that there is atrade-off in nitrogen partitioning between photosynthesis and cell walls. We studied contents of Rubisco (keyenzyme of photosynthesis) and cell walls in leaves of 26 species with a large variation in photosynthetic
rates, which covered almost half of its global variation. Our results demonstrated that Rubisco-use efficiency(RUE, photosynthetic rate per Rubisco) explained most of the interspecific variation in photosynthetic rates,
while nitrogen allocation to Rubisco had a significant but smaller contribution. Our analyses suggested that
RUE was altered by the content of cell wall, which probably affected mesophyll conductance for CO2 diffusion. Cell wall nitrogen increased with increasing leaf mass per area, but it did not directly affect the variationin photosynthetic rates. Species with low photosynthetic rates invest more resources in cell walls at theexpense of RUE.

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P1

Nitration of peripheral proteins of photosystem II by atmosphericnitrogen dioxide suppresses oxygen evolution in plants

Misa Takahashi1, Jun Shigeto1, Kozi Asada2, Atsushi Sakamoto1
and Hiromichi Morikawa1
1

Depart. Math. & Life Sci., Grad. Sch. Sci., Hiroshima Univ.,
2Fac. Engin., Fukuyama Univ.

Nitrogen dioxide (NO2) has been known as an air pollutant that suppresses the photosynthesis in plants.
However, the molecular mechanism is still unclear. In this communication, we investigated by means of antibody-based proteomics nitration of proteins in Arabidopsis thaliana leaves that were fumigated with 4-40
ppm NO2. We found that immunoreactive protein spots were identified almost exclusively to be PsbO or
PsbP, peripheral proteins of the oxygen evolving complex (OEC) of PSII. The same was true when isolated
thylakoid membranes were treated with NO2. A positive linear relationship was observed between NO2induced nitration of PsbO/PsbP and NO2-mediated inhibition of oxygen evolution in isolated thylakoid membranes. The nitration of PsbO/PsbP by NO2 was found to be accelerated by light and reactive oxygen. We
therefore hypothesize that nitration of tyrosine residues of PsbO/PsbP proteins in the OEC is involved in theinhibition of photosynthetic oxygen evolution by stresses such as reactive nitrogen, reactive oxygen andlight. Furthermore, the western blot analysis using the anti-3-nitrotyrosine antibody of Daphniphyllum
macropodum, a woody plant species, also strongly suggested that its PsbO/PsbP proteins were nitrated upon
fumigation with NO2.

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P2

P3

Analysis of regulatory mechanisms of plant growth
in response to light environments

Changes in Rubisco content during leaf developmentin Eucalyptus globulus

Y. Suzuki1, T. Kihara-Doi2, T. Kawazu2 and A. Makino1
Tatsuya Sakai

1Lab. Plant Environ. Resp., Grad. Sch. of Agric. Sci., Tohoku Univ.
2
Forest. Res. Inst., Oji Paper Company Ltd.

RIKEN Plant Science Center

Plants regulate their growth directions in response to light direction to optimize light capture for photo-

Rubisco (EC. 4. 1. 1. 39) is a key enzyme in photosynthesis and the most abundant leaf protein in higher

synthesis, and its response is called phototropism. In higher plants, phototropism is explained by theplants and changes in its content during leaf development is important in both the C and N economy of the

Cholodny and Went hypothesis, which proposes that the asymmetric distribution of the phytohormone auxin

plant. In grass plants, Rubisco content increases during leaf expansion, becomes maximum at maturation andcauses the differential growth and consequent bending of plant organs, and three major families of photore-

gradually declines during senescence. In rice and soybean, Rubisco synthesis is active before leaf maturation

ceptors, phototropins, phytochromes, and cryptochromes, coordinately regulate its response. We are study-

but rapidly declines thereafter, whereas its degradation becomes active (1,2). Thus, changes in Rubisco con-ing on these molecular mechanisms by a molecular genetic approach using Arabidopsis thaliana mutants, andtent are a result of dramatic changes in balance of protein turnover. In woody plants, on the other hand, infor-

identified several signaling factors in this response. We identified a novel blue-light photoreceptor phot2, andmation on Rubisco turnover is not available. In this study, changes in Rubisco content and it synthesis wereindicated that phot1 and phot2 show partially overlapping functions in the phototropic response in a fluence

examined in Eucalyptus globulus seedlings. Plants were hydroponically grown in a greenhouse. All axillaryrate-dependent manner. Phototropin signaling probably controls the auxin transport activities to generate thebuds were removed just after their emergence and difference in leaf position approximately reflected that inasymmetric distribution of auxin, and we are now studying about its molecular mechanisms. In addition, ourleaf age by this treatment. At 4.5 months after sowing, the plants were N-labeled then leaves at different

current results indicated that Arabidopsis hypocotyls contain not only phototropism-inducing mechanisms but

positions are collected. The amount of Rubisco per unit fresh weight slightly increased with leaf expansion,

also phototropism-suppressing mechanisms, and that photoreceptors, phytochromes and cryptochromes

became maximal in uppermost fully expanded leaves, was kept constant in leaves at middle position, thenenhance the phototropic response by removing suppressors of the phototropic response. One of the pho-declined in lower leaves. The amount of Rubisco synthesized per unit fresh weight was maximal in the

totropism-suppressing mechanisms was found to be mediated through the ABC-type auxin transporter

expanding leaves, rapidly declined and became quite low after full expansion. Rubisco was scarcely synthe-

15

ABCB19, and activations of phytochromes and cryptochromes suppress the ABCB19 expression and enhance

sized in leaves at middle and bottom positions. Therefore, it is suggested in Eucalyptus globulus that an

the phototropic response indirectly. In this symposium, I introduce our results and new finding in this field.

increase in Rubisco content in expanding leaves was accounted for by its active synthesis, whereas Rubisco
content was kept constant by slow protein turnover after leaf maturation and Rubisco degradation became
active in late stage of leaf development. This pattern is basically the same as in rice and soybean.

References(1) Mae T, Makino A, Ohira K (1983) Plant Cell Physiol 24, 1079
(2) Tonouchi A, Makino A, Mae T, Ohira K (1988) Jpn J Soil Sci Plant Nutr 59, 573

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P5

Tree Physiology Research for Increasing the Carbon Sequestration
and Photosynthetic Capacity of Forest Ecosystems

Genetic transformation of the symbiotic nitrogen-fixing bacteriumFrankia

Hiroaki Ishii

Ken-ichi Kucho, Kentaro Kakoi, Masatoshi Yamaura, Shiro Higashi,
Toshiki Uchiumi, and Mikiko Abe

Graduate School of Agriculture, Kobe University

Department of Chemistry and Bioscience, Faculty of Science, Kagoshima University

Of the various terrestrial ecosystems, forests hold the largest carbon store. Atmospheric CO2 concentra-

Nitrogen is an essential element for living organisms. In plant, nitrogen plays an important role as a con-tion could potentially be reduced by accelerating carbon uptake by forest ecosystems. Development of new

stituent of chlorophyll. Therefore nitrogen supply from soil is a critical factor delimiting the efficient growthtree varieties with high carbon sequestration capabilities could potentially increase carbon uptake throughof plants. Actinorhizal plants such as Alnus and Casuarina establish symbiosis in root nodules with a nitro-reforestation. We have identified several phenotypic characteristics that could potentially increase tree pho-gen-fixing actinobacterium Frankia and utilize N2 gas in atmosphere as a nitrogen source. Actinorhizal plants

tosynthesis. Plasticity of needle morphology and their arrangement on twigs, as well as the allocation ofare mostly woods and grow rapidly even under nitrogen-limited conditions. However, molecular basis of thechlorophyll and other enzymes within the crown are important characteristics that allow trees to capture

symbiosis is largely unknown because genetic manipulation of Frankia has not been feasible. In this study,

light efficiently. The present study aims to apply these findings to develop tree varieties with high photosyn-

using novel technical attempts, we succeeded in transforming Frankia sp. strain CcI3 which make symbiosis

thetic capacities. Our goal is to elucidate the contribution of morphological and allocational plasticity towardwith Casuarina species. We generated fusion marker genes consisting of a tetracycline resistance gene withincreasing photosynthetic capacity and to elucidate the quantitative genes that determine these traits.

a high codon usage similarity to Frankia’s and promoters of the strain’s translation initiation factor 3 gene.
We flanked the fusion genes with 4-kb genomic sequences from strain CcI3 in the expectation that theywould be integrated into the targeted site by homologous recombination. We introduced the transformation
constructs into Frankia cells by electroporation and selected transformants in liquid media. The growth ofantibiotic resistant cells was observed depending on the presence of construct DNA. Using genomic PCR andreverse transcriptase-PCR analysis, we confirmed that the marker genes had been introduced into theFrankia cells. Integration of the marker genes into the chromosome by homologous recombination did occur,
but at a low frequency. When we cultured the transformants in fresh selection media, the proportion of thecells containing marker genes was reduced, suggesting that the cultures had generated spontaneous antibiotic resistant mutants. Although several aspects of our procedure need to be improved, we believe that theresults mark substantial progress in Frankia genetics.

Morphological changes of Picea glehnii (left) and Picea
jezoensis (right) planted on nutrient poor volcanic ash (shortshoots) and nutrient rich forest soil (long shoots). Suchchanges have consequences for photosynthetic rate andstand productivity.

Morphological changes observed along the verticalgradient in the canopy of a 100m-tall Sequoia sempervirens tree. Such changes have consequences
for photosynthetic rate per light capturing area.

Ishii H, Jennings GM, Sillett SC, Koch GW (2008) Hydrostatic constraints on morphological exploitation of light in tall Sequoia
sempervirens trees. Oecologia 156:751-763
Ishii H, Kitaoka S, Fujisaki T, Maruyama Y, Koike T (2007) Plasticity of shoot and needle morphology and photosynthesis of
two Picea species with different site preferences in northern Japan. Tree Physiology 27:1595-1605
Ishii H, Ooishi M, Maruyama Y, Koike T (2003) Acclimation of shoot and foliage morphology and photosynthesis of two Picea
species to differences in soil nutrient availability. Tree Physiology 23:453-461

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P7

Functional analysis of nuclear-genes for chloroplast developmentusing albino mutants in Arabidopsis

pfkB-type carbohydrate kinase family protein, NARA5, is essential
for the massive expressions of plastid-encoded photosynthetic genes
in Arabidopsis thaliana

Reiko Motohashi1, Tomoko Kato1, Miyuki Hara1, Kyosuke Matsuura1,
Shunichi Itayama1, Yuka Akaike1, Fumiyoshi Myouga2, Noriko Nagata3
and Kazuo Shinozaki2
1

2

3

Shizuoka University, RIKEN Plant Science Center, Japan Women’s University

Taro Ogawa1, Kenji Nishimura1, Ken-Ichi Tomizawa2, Hiroki Ashida1
and Akiho Yokota1
1

Graduate School of Biological Sciences, Nara Institute of Science and Technology,
8916-5 Takayama, Ikoma, Nara 630-0192, Japan.
2
Research Institute of Innovative Technology for the Earth (RITE), 9-2 Kizugawadai,
Kizugawa-shi, Kyoto 619-0292, JapanTo determine essential nuclear-genes involved in chloroplast development, we systematically analyzed

The massive accumulation of photosynthetic proteins in chloroplasts depends on many nucleus-encodedalbino or pale green mutants in Arabidopsis. We have isolated about 40 mutants with albino or pale green (apg)

factors in higher plants. In order to identify genes involved in the massive accumulation of photosynthetic

phenotypes. Identified APG genes have sequence homology with house keeping proteins involved in photo-proteins including RuBisCO, we have isolated the twelve Arabidopsis EMS mutants that show low RuBisCO

synthesis, translation, transcription, translocation and so on. In this symposium, we present phenotypes ofamounts. These were named nara (genes necessary for the achievement of RuBisCO accumulation) mutants.

six apg mutants (apg4, apg9, apg11, apg12, apg14 and apg15), and discuss functions of these APG genes inAmong them, nara5-1 showed a markedly decrease in plastid-encoded photosynthetic proteins including

chloroplast development.

RuBisCO. Map-based cloning revealed that NARA5 encodes a chloroplast pfkB-type carbohydrate kinase

The apg4 mutant has a disrupted gene for a ribosome binding factor RBFA homologue. The phenotypes

family protein of unknown function. Analysis of photosynthetic gene expressions during light-induced green-of the apg4 mutant had white cotyledons and yellow or green variegated true leaves. In Escherichia coli, theing of etiolated seedlings in nara5-1 and T-DNA insertion mutant, nara5-2, indicates that NARA5 is essential

RBFA was shown to be involved in processing of the pre-rRNA to form the mature 16S rRNA. We found thatfor the massive expressions of plastid-encoded photosynthetic genes, particularly in rbcL.

the APG4 is involved in processing of the pre-rRNA to form the mature 23S and 4.5S rRNA and related accumulation of rrn16 transcripts. The effect on the apg4 mutation gradually decreased as plant grew, which may
be due to high expression of the APG4 gene in cotyledon but not in true leaves. We predicted that other proteins function as APG4 in true leaves. It was reported that RimM (21-kDa protein formerly called 21K) andEra (E. coli Ras-like) have similar functions of RBFA in E. coli. To analyze the relation between APG4 andthese genes, we identified their homologous genes in Arabidopsis thaliana. We report the function andexpression of these genes closely related to APG4.
APG9, APG14 and APG15 have DNA or RNA binding domains. We found that mRNA of chloroplastencoded genes have processing defect in these mutants. We report that these proteins related in processing
and stability of chloroplast transcripts, too.

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─ 35 ─P8

P9A DEAD-box RNA Helicase RH39 Is Required for Chloroplast 23SrRNA Processing and Essential for Plant Development
in Arabidopsis thaliana

The long-term responses of the photosynthetic proton circuit
to drought
Kaori Kohzuma1, Jeffrey A. Cruz2, Kinya Akashi1, Saki Hoshiyasu1,
Yuri Munekage1, Akiho Yokota1 and David M. Kramer2
1

Kenji Nishimura, Taro Ogawa, Hiroki Ashida, Akiho Yokota
Grad. Sch. Biol. Sci., Nara Inst. Sci. Technol.

Graduate School of Biological Sciences, Nara Institute of Science and Technology, (NAIST),
8916-5 Takayama, Ikoma, Nara, 630-0192, Japan.
2
Institute of Biological Chemistry, Washington State University, 289 Clark Hall, WSU,
Pullman, WA 99164-6340, USA.
e-mail: akashi@bs.naist.jp

In recent years, chloroplasts have attracted attention as a place to synthesize large amounts of foreign

Proton motive force (pmf) across thylakoid membranes is of crucial importance, not only for harnessing

proteins because of their high potential for protein synthesis. However, the molecular mechanisms forsolar energy for photosynthetic CO2 fixation, but also for triggering feedback regulation of photosystem II

chloroplast protein synthesis have not been fully understood in higher plants. To gain insight into the mecha-antenna. The mechanisms for balancing these two roles of the proton circuit under the long-term environ-nism of chloroplast protein synthesis, we have characterized the nara12-1 (the gene necessary for the achieve-

mental stress, such as prolonged drought, have been poorly understood. In this study, we report on thement of RuBisCO accumulation) mutant of Arabidopsis with impairment of the chloroplast translation.

response of wild watermelon thylakoid 'proton circuit' to drought stress using both in vivo spectroscopy andPositional cloning of NARA12 identified a DEAD-box protein RH39. Transient expression of the N-terminus

molecular analyses of the representative photosynthetic components. While drought stress led to enhancedof the RH39-GFP fusion protein in tobacco leaves suggested that RH39 was localized in chloroplasts.

proton flux via a ~34% increase in cyclic electron flow around PS I, an observed ~5-fold decrease in proton

Northern blot analysis revealed that chloroplast 23S rRNA processing was defective in nara12-1. RH39 null

conductivity, gH , across thylakoid membranes suggested that decreased ATP synthase activity was theallele nara12-2 was embryonic lethal due to abnormal seed formation. Our results suggest that RH39 ismajor factor for sustaining elevated qE. Western blotting analyses revealed that ATP synthase content

essential for chloroplast rRNA maturation and plant development.

decreased significantly, suggesting that quantitative control of the complex plays a pivotal role in down-regu-++

lation of gH . The expression level of cytochrome b6 f complex —another key control point in photosynthesis— also declined, probably to prevent excess-reduction of PS I electron acceptors. We conclude that plant
acclimation to long-term environmental stress involves global changes in the photosynthetic proton circuit,in which ATP synthase represents the major key control point for regulating the relationship between electron transfer and pmf.

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─ 37 ─P10

P11

Energy conversion efficiency by Photosystem II assembled withvariant copies of subunit D1 in themophilic cyanobacterium
Themosynechococcus elongates

Probing photosynthesis in the living plant: What can we learn
about the limits of photosynthetic energy conversion efficiency?

Miwa Sugiura1, Fabrice Rappaport2 and Alain Boussac3
David M. Kramer

1

Cell-Free Science and Technology Research Center, Ehime University,
3
Institut de Biologie Physico-Chimique, CNRS, and iBiTec-S, CEA Saclay.

2

Institute of Biological Chemistry. Washington State University, Pullman, WA 99164

The world is more and more confronted to energetic problems. In nature, at the heart of Photosystem II

This presentation will cover recent developments in the non-invasive measurement of photosynthetic(PSII) is the reaction centre where light energy is quite efficiently converted into electrochemical potential

processes under steady-state conditions.

The light reactions of photosynthesis are replete with species

energy and where the water-splitting reaction occurs. In so doing, it releases dioxygen into the atmospherewhich respond to changes in physiological state. Many of these species can be probed using non-invasive

and provides the reducing equivalents required for the conversion of CO2 into the organic molecules of life.

techniques, allowing us to investigate the inner workings of plants as they function in living plants. I will

PSII complex is a membrane-spanning complex that is constituted of at least 20 subunits, 17 small

present an integrated review of the types of measurements available that allow us to probe light absorption,

polypeptides and three extrinsic proteins. The reaction centre consists of two homologous proteins known

electron transfer, proton transfer, ATP synthesis, regulation of antenna function, photodamage and it repair.

as D1 and D2 which have five transmembrane a-helicies each. The active site for water oxidation in PSII
goes through five sequential oxidation states (S0 to S4) before O2 is evolved. It consists of a Mn4Ca-cluster
which metal ions ligate to amino acid residues of D1 and D2 polypeptides of PSII complex.
Thermophylic cyanobacterium Themosynechococcus elongatus has higher oxygen water oxidation activity
than the other oxygenic photosynthetic organisms. The genome of T. elongatus possesses three variant
copies of D1 genes (psbA1 - psbA3), which the amino acid sequences are not identical although importantamino acid residues for photosynthetic function such as electron transfer and ligand for co-factors. In thisstudy, we examined about properties of PSII which is composed of variant copies of D1 including energy conversion efficiency, water oxidation function, and response to stress conditions.
Under usual environmental cultivation conditions, psbA1 constitutively expressed. When T. elongatus
cells were exposed to strong light and low temperature, expression of psbA3 was induced. Water oxidation in
PSII composed of PsbA3, genetically knocked out psbA1 and psbA2, was 1.7 times faster than in PSII composedof PsbA1. In thermodynamic properties, the potential difference between S3 state (donor side) and plasto--quinone QB (acceptor side) in PSII-PsbA3 was smaller than PSII-PsbA1. And the redox potential of QA wasstrongly modified. These results suggest that the structural modification of PsbA around acceptor side controls energy conversion efficiency by PSII.

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