bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lipids of Cuscuta reflexa and changes in lipids of its host plants after infection
Authors: Sharma Shobha , Khanna Raj , Sanwal G. G. 
Published: April 2006

The lipid level (fresh weight basis) of Cuscuta reflexa Roxb. was related to the lipid content of the host plants Meilicago saliva L., Helianthus annuus L., Pisum sativum L. and Lantana camara L. Parasitizing by the dodder significantly increased the total lipid level of the hosts. The increase was mainly due to enhancement in the neutral lipid fraction.The level of phospholipid in the parasite was always higher than in its hosts. Phospholidyl choline and phosphatidyl ethanolamine constituted about 65% of the total phospholipid of Cuscuta. This was followed by phosphatidyl inositol (ca 20%) and phosphatidyl glycerol (ca 12%). Phosphatidic acid constituted only ca 3% of the phospholipids of Cuscuta. Although the total phospholipid levels of various host plants were not affected as a result of the infection by Cuscuta, a significant decrease occurred in the levels of phosphatidyl eholine and phosphatidyl ethanolamine as well as marked increases in phosphatidyl inositol and phosphatidic acid. The infected tissue showed an increase in phospholipase D activity as compared with the controls. The results have been discussed in relation to changes in permeability of the infected tissue.
Photosynthesis of Coffea arabica after chilling
Authors: Bauer H. , Wierer R. , Hatheway W. H. , Larcher W. 
Published: April 2006

Net photosynthetic CO2 exchange of 1‐year‐old plants of Coffea arabica L. was studied after the above‐ground parts had been exposed once or repeatedly to night temperatures in the chilling range. Chill‐reduced rates of CO2 uptake (measured at 24°C and at natural CO, level) were observed after a 12 h night exposure to about 6°C. After exposure to 4°C, activity was reduced to less than half of that of the controls, and after exposure to 0.5°C the leaves suffered visible necrotic injury and were no longer able to take up Co2 If the leaves were not lethally injured, net photosynthesis recovered completely within 2 to 6 days. About 25% of chill‐induced reduction of CO2 uptake was due to reduced stomatal aperture and 75% to impairment of carboxylation efficiency.Chilling on successive nights at 4–6°C reduced CO, uptake progressively on each day following treatment. After 10 nights, activity was decreased to less than 10% of initial performance. Conditioning at temperatures slightly above the chilling level (e.g. 15/I2°C) for 2 weeks led to almost complete impairment of photosynthetic activity without additional chilling stress instead of improving chilling tolerance.
A fluorescent compound in oat root plasma membrane
Authors: Møller Ian M. , Lundborg Tomas 
Published: April 2006

Homogenates of 7‐day‐old oat (Avena sativa L. cv. Brighton) roots were highly fluorescent (excitation and emission maxima around 360 and 440 nm, respectively). Less than 1/10 as much fluorescence per g fresh weight was found in oat shoots or in wheat (Triticum aestivum L. cv. Drabant) roots or shoots. Most of the fluorescence of oat roots was found in the soluble fraction (150 000g supernatant). However, some could be detected in the plasma membrane fraction (excitation and emission maxima 365 and 417 nm, respectively), which contained a 3‐fold higher fluorescence per mg protein than the homogenate.Growth of oat or wheat in a medium containing, 10‐−5M scopoletin (6‐methoxy‐7‐hy‐droxy coumarin), a fluorescent compound previously reported to be present in both wheat and oat roots, caused the disappearance of scopoletin from the medium (proportional to the amount of roots) and the appearance of increased fluorescence in the root homogenates but not in the shoot homogenates. In both oat and wheat roots ail of the extra fluorescence was recovered in the soluble fraction and at least in wheat it consisted of unconverted scopoletin. The concentration of scopoletin in wheat roots grown in 10‐−5M scopoletin was around 50 nmol (g fresh weight)−1, or about five times the concentration in the growth medium. Scopoletin in the growth medium (10‐−5M) or in the assays (up to 10‐−4M) did not affect Mg2+‐, Mg2++K+‐ or Ca2+‐ATPase activities in wheat or oat roots.The fluorescence properties of the oat plasma membrane were different from those of authentic scopoletin. Either the surroundings modify the fluorescence of membrane‐associated scopoletin or the endogenous fluorescent compound is not scopoletin but a glycoside‐derivative of scopoletin or some completely unrelated compound.
Phototransformation of oat phytochrome with millisecond and submillisecond flashes: The level of the photostationary Pfr/Ptot ratio is modified by photoreversible intermediates
Authors: Scheuerlein Robert , Sundqvist Christer , Haupt Wolfgang 
Published: April 2006

Photoconversion of the red‐absorbing form of phytochrome (Pr) to the far‐red‐absorbing form of phytochrome (Pfr) and vice versa has been measured spectrophotometrically at 10°C in immobilized and soluble phytochrome (118 kdalton), prepared from 5‐day‐old etiolated oat seedlings (Avena saliva L. cv. Sol II). The photostationary equilibrium φ= PfrPtot (with Ptot= total amount of phytochrome Pr+ Pfr) for red light depends on whether it is established by repetitive pulses (≥ 5 s) or by repetitive flashes (≥ 4 ms). In the wavelength region around 660 nm, a lower φ is reached with flashes as compared to that with pulses. This difference becomes negligible if the wavelength is shortened to the 600 nm region, and it also disappears if the fluence of each individual flash is reduced. In contrast, in long‐wavelength red light and short‐wavelength far‐red light, a higher φ is reached with flashes than with pulses.We relate the differences in φ for flash and pulse irradiation to photochromic systems between Pr and photoreversible intermediates in the phototransformation pathway Pr→ Pfr. Thus, light absorption by phytochrome intermediates can be limiting for the quantitative relationship between light signal and Pfr formed.
Esters hydroxycinnamiques et induction photopériodique florale in vitro chez Cichorium intybus
Authors: Badila P. , Paulet P. 
Published: April 2006

Hydroxycinnamic acid esters and photoperiodic flowering induction in vitro of Cichorium intybus.In root tissues of Cichorium intybus L. cv. Witloof cultured in vitro, the photoinductive period occurs between the 8th and the 16th day after the start of the culture. The promotive light conditions are either long days (16 h photoperiod) or daily cycles of 9 h white + 15 h red light applied during the photoinductive period in an otherwise short day treatment. During the photoinductive period and under suitable irradiation conditions, the endogenous hydroxycinnamic acid esters (especially chlorogenic acid) show a regular development as from the 8th day, reaching a maximal level by the 16th day. The amount of these molecules then decreases rapidly, preceding the external expression of floral induction. When we apply non‐inductive conditions [short days (9 h) or daily cycles of 9 h white + 15 h (far‐red + red) light supplied from the 8th to the 16th day in otherwise short day conditions], the metabolic changes indicate the same pattern during the inductive period as mentioned above. However, a fundamental difference exists between the inductive and non‐inductive conditions, so that the production of hydroxycinnamic acid esters is particularly high towards the end of the second week of in vitro development in the induced state. This increase is not primarily due to increased photosynthetic activity in long day conditions, since it occurs both in the long day treatments and in the treatments with daily cycles of 9 h white + 15 h red light, thus revealing the morphogenetic action of light via phytochrome. This accumulation of hydroxycinnamic acid esters is correlated with floral induction, which appears to be ineffective unless there is a certain minimum amount of these molecules in the tissues.
Ion supply capacity of roots in relation to rejuvenation of primary leaves in vivo
Authors: Neumann Peter M. , Stein Zipporah 
Published: April 2006

Removal of the shoot above the primary node (detopping) of 3‐week‐old bean plants (Phaseolus vulgaris L. cv. Contender) altered the metabolism and development of the remaining leaves. An increase in levels of chlorophyll, protein, stomatal opening, photosynthesis and growth, i.e. rejuvenation of primary leaves, was established within 7 days of detopping. These levels were maintained while the primary leaves of equivalent intact plants senesced.The flux of xylem solution (mineral ions, cytokinins and water) into leaves is related to the leaf area to be supplied and root supply capacity; it has been suggested that detopping leads to an increased availability of root‐supplied solutes and hence rejuvenation of the remaining leaves. This assumes however that root output of solutes is not decreased by the defoliation treatment.We found that root output of ions (electrical conductivity of passive xylem exudate) in detopped plants was 30% lower than in intact plants after 24 h and 60% lower after 7 days. The output of Ca2+, Mg2+ and K+ were similarly reduced 7 and 14 days after detopping as were fresh and dry weights of roots. Furthermore, neither the calculated xylem flux of ions nor directly measured levels of Ca2+, Mg2+ and K+ were significantly increased in leaves of detopped plants during their rejuvenation. We therefore conclude that root output is tightly coupled to shoot demand and that the apparent rejuvenation of primary leaves caused by detopping bean plants is not a consequence of increased xylem flux of mineral ions into the leaves.
Ethylene and ethane release during tobacco protoplast isolation and protoplast survival potential in vitro
Authors: Cassells Alan C. , Tamma Lakshmi 
Published: April 2006

Studies on stress ethylene and ethane during protoplast isolation from water‐stressed and waterlogged donor plants Nicotiana tabacum L. xanthi‐nc, show a correlation between ethane, but not ethylene, release and protoplast survival in vitro. Ethane release shows a high negative correlation with protoplast survival potential from donor plants subjected to both stresses. Ethylene showed a high negative correlation with protoplast survival potential in tissues from water‐stressed but not from long‐term waterlogged plants. The absence of correlation in the latter may be related to decreased ability to produce ethylene in hyperstressed plants.The results are discussed in relation to the use of stress ethane release as a parameter of the physiological status of the plant.
The increasing desiccation sensitivity of recalcitrant Avicennia marina seeds with storage time
Authors: Farrant Jill M. , Pammenter N. W. , Berjak Patricia 
Published: April 2006

To test the hypothesis that desiccation sensitivity increases with storage time, recalcitrant seeds of Avicennia marina (Forssk.) Vierh. were dehydrated by soaking in polyethylene glycol solutions after inreasing periods of storage. Germination characteristics and the ultrastructure of root primorida were assessed before and after dehydration. Short‐term storage enhanced the apparent rate of germination, consistent with the hypothesis that these seeds commence germination in storage. Root primordia of stored seeds initially showed enhanced subcellular activity, including cell division and vacuolation. Increased storage time resulted in the onset and progression of deleterious changes.Newly shed seeds and seeds stored up to the stage of cell division were comparatively resistant to desiccation. As storage time increased, subsequent dehydration caused increasing subcellular damange and consequent reduction in the rates of germination relative to non‐dehydrated controls. Ultrastructural results suggest that after the initiation of cell division of seeds in storage, there is a requirement for additional water for the germination process to continue. A model for the behaviour of recalcitrant seeds is proposed.
Characterization of prolamellar bodies, from dark‐grown seedlings of Scots pine, containing light‐ and NADPH‐dependent protochlorophyllide oxidoreductase
Authors: Selstam Eva , Widell Anna 
Published: April 2006

Cotyledons of conifers have a light‐independent pathway for chlorophyll biosynthesis. To investigate whether the prolamellar body of Scots pine (Pinus sylveslris L.) is similar to the better known prolamellar body of wheat, etioplast membrane fractions were isolated from cotyledons of dark‐grown Scots pine. Dark‐grown cotyledons contained both chlorophyll and protochlorophyllide, 158 and 10 nmol (g fresh weight)’respectively, and had a chlorophyll a to b ratio of 4.2. The content of glyco‐ and phospholipids was 7.1 μmol (g fresh weight)1. About 40 mol % of these lipids were the specific plastid lipids – monogalactosyl diacylglycerol. digalactosyl diacylglycerol and sulfoquinovosyl diacylglycerol in the relative amounts 50, 35 and 7 mol %. The mol ratio of monogalactosyl diacylglycerol to digalactosyl diacylglycerol was 1.7. Low temperature fluorescence emission spectra of intact cotyledons and homogenate showed maxima at 633, 657, 686, 696 nm and a broad peak at 725–735 nm. The maxima at 633 and 657 nm represented different forms of protochlorophyllide and the other emission maxima represented chlorophyll protein complexes. The 657 nm form of protochlorophyllide was phototransformable both in vivo and in the isolated membranes. The phototransformable protochlorophyllide was substantially enriched in the prolamellar body fraction.The specific activity of light dependent protochlorophyllide oxidoreductase in the prolamellar body fraction was found to be 2 nmol chlorophyllide formed [(mg protein)−1 min−1]. The molecular weight of the enzyme polypeptide was determined as 38 000 dalton with sodium dodecylsulphate‐polyacrylamide gel electrophoresis.
Localization of ornithine decarboxylase and changes in polyamine content in root meristems of Zea mays
Authors: Schwartz M. , Altman A. , Cohen Y. , Arzee T. 
Published: April 2006

Polyamine content and the activity of arginine decarboxylase (EC 4.1.1.19) and ornithine decarboxylase (EC 4.1.1.17) were studied with respect to meristematic activity in primary roots and in developing lateral roots of Zea mays L.(cv. Neve Ya'ar 170) seedlings. Comparative localization of active ornithine decarboxylase and of meristematic activity were determined by labelling roots either with α‐[5‐14C]‐difluoromethyl ornithine or with [3H]‐thymidine, respectively.Lateral roots were formed during the 72 h post‐decapitation period, accompanied by an initial decline in putrescine content and by a significant increase in spennidine con‐tent at 48–72 h. High levels of spermidine and lower levels of putrescine were found in the primary root apex as well. A marked increase in ornithine and arginine decarboxylase activity, as measured by 14CO2 release, was found during the 72 h post‐decapitation period of lateral root development. This increase in ornithine decarboxylase activity was confirmed also by a parallel rise in the incorporation of α‐[5‐14C]‐difluoromethyl ornithine into trichloroacetic acid‐insoluble fractions. Microautoradiographs of longitudinal and cross sections of roots, labelled with α‐[5‐14C]‐difluoromethyl ornithine, showed that ornithine decarboxylase is localized mainly in the meristematic zones, as evidenced by [3H]‐thymidine incorporation. A close correlation between meristematic activity and polyamines was demonstrated in situ, suggesting that polyamine content and biosynthesis may have a role in meristematic activity in corn roots.
Daily changes in uptake, reduction and storage of nitrate in spinach grown at low light intensity
Authors: Steingröver Eveliene , Ratering Pieter , Siesling Johan 
Published: April 2006

Under poor light conditions, as normally used during winter production of greenhouse vegetables, the nitrate concentration in the shoot of spinach (Spinacia oleraceaL. cv. Vroeg Reuzenblad) showed a diurnal rhythm. This rhythm was mainly caused by a decrease during the day, followed by an increase during the night in the leaf blade nitrate concentration. Nitrate was mainly located in the vacuoles of the leaf blades. A strong correlation was found between net uptake of nitrate by the roots and the nitrate concentration in the leaf blade vacuoles. The nitrate concentration in the leaf blades increased during the initial hours of the night. This increase was caused by a marked increase in the net uptake rate of nitrate by the roots during the first hours of the dark period. During the second part of the night both net uptake rate of nitrate by the roots and the vacuolar nitrate concentration in the leaf blades remained constant.We conclude that nitrate is taken up for osmotic purposes when light conditions are poor because of a lack of organic solutes. During the night, nitrate influx into the vacuole is needed for replacement of organic solutes, which are metabolized during the night, and possibly also for leaf elongation growth. During the day, vacuolar nitrate may be exchanged for newly synthesized organic solutes and be metabolized in the cytoplasm. A strong diurnal rhythm in nitrate reductase (NR; EC 1.6.6.1.) activity was absent, due to the poor light conditions, and in vitro NR activity was not correlated with nitrate flux from the roots. In vivo NR activity also lacked a strong diurnal rhythm, but it was calculated that in situ nitrate reduction was much lower during the night, so that the major nitrate assimilation took place during the day.
Screening a Wheat Collection for Leaf Position at Different Stages of Growth
Authors: Borojević S. , Denćić S. 
Published: April 2006

AbstractA collection of hexaploid ‐wheat consisting of 1400 entries from 36 countries was screened for leaf position at four stages of growth over two years. At the shooting stage, more than 80 % of the entries showed the curved position of the flag and the second leaf, about 15 % the erect position, while the horizontal position did not occur. At the heading stage more than 10 % of the genotypes with curved and some with erect position assumed horizontal position. At the milk stage, half of the genotypes with the erect position in earlier stages of growth assumed horizontal and even pendulous position; the majority of genotypes had curved position of leaves. At the dough stage, only about 2 % of the genotypes maintained erect flag leaf position, while 45 % had curved and about 45 % pendulous position of leaves.When an erect leaf assumes horizontal position, the lamina is completely straight without any curving, which is different from genotypes classified as having horizontal position at heading and milk stage. The position of the second leaf, in general, followed the pattern of the flag leaf. Through the stages of growth the curved position was more stable than either erect or horizontal positions. Leaves were more erect and stable in position under conditions with lower rainfall and higher temperatures (1983) than in the rainy year with lower temperatures (1984). Most of the high‐yielding cultivars with short straw had a curved position, which is probably the consequence of unintended selection to fit a dense canopy.
Hybrids of Bread Wheat (Triticum aestivum) with Thinopyrum scirpeum (4x) and Thinopyrum junceum (6x)
Authors: Gupta P. K. , Fedak G. 
Published: April 2006

AbstractHybrids were obtained by crossing Thinopyrum scirpeum (4x) and T. junceum (6x) onto Triticum aestivum cv, ‘Chinese Spring’. An average meiotic pairing of 24.44I+ 5.07II+ 0.14IIIin the ‘Chinese Spring’×T. scirpeum hybrid (ABDE1E2) is attributed to two similar genomes from T. scirpeum (E1E2E3E4). An average meiotic chromosome pairing in the other hybrid (ABDJ1J2E3) was 31.70I+ 3.80II+ 0.90III and is attributed to autosyndetic pairing between the three genomes of T. junceum.
Effect of D‐Genome Chromosome Substitutions on Hybrid Seed Development and Viability in T. turgidum var. durum X S. cereale Crosses
Authors: de V. Pienaar R. , Marais G. F. 
Published: April 2006

Abstract Triticum turgidum var. durum cv. ‘Langdon’ and the set of D‐genome disomicsubstitutions in ‘Langdon’, produced at Fargo, U.S.A., were grown in a temperature controlled greenhouse and crossed with diploid spring rye (Secale cereals), to determine the effect of each substitution on 1. the crossability with rye, and 2, the viability of the resulting hybrids kernels. None of the disomicsubstitutions lines, with the possible exception of the 5D (5Bj line, gave an appreciable improvement in hybrid kernel set, ‐development, and ‐viability over the control, ‘Langdon’ The post‐zygotic barrier to endosperm and embryo development, which operates in crosses between durum wheat and rye, could therefore not be suppressed by any specific chromosome of the D‐genome.
Self‐Compatibility/Incompatibility in Some Orchids of the Subfamily Vandoideae
Authors: Agnew J. D. 
Published: April 2006

AbstractSelf‐pollination of 2f species of vandaceous orchids was followed by later embryo culture carried out to determine which species are self‐compatible (SC) or incompatible (SI): 10 are SC, 1 are SI and the remaining:8 require further study. In the SI species, a few progeny could usually be recovered and these are interpreted as arising from mutation at the incompatibility locus (loci). The implications of the findings for current models of incompatibility are discussed.
Recurrent Addition of the Pennisetum americanum Genome in a P. americanum×P. orientale Hybrid
Authors: Zado S. N. , Singh Amar 
Published: April 2006

AbstractAn interspecific hybrid involving Pennisetum americanum (2 n = 14) and a diploid cytotype of P. orientale (2 n = 18) was backcrossed to P. americanum using the hybrid (2 n = 16, 7‘A’+ 9 ‘O’) as the female parent. Pollen mother cells of 13 BC1 plants contained a complement of 14‘A’+ 9 ‘O’ chromosomes. Five BC2 plants obtained through further backcrossing to P. americanum had 21‘A’+ 9 ‘O’ chromosomes revealing another addition of the P. americanum genome. The role of such recurrent additions of parental genomes in the evolution of polyploid species has been discussed.
A Major Gene for Delayed Senescence in Maize. Pattern of Photosynthates Accumulation and Inheritance
Authors: Gentinetta E. , Ceppl D. , Lepori C. , Perico G. , Motto M. , Salamini F. 
Published: April 2006

AbstractA description is given of the major modification induced in the pattern of photosynthates accumulation by the delayed senescence behaviour of the maize inbred line Lo87602. The major effects noted are: (1) high water and chlorophyll contents in leaves at physiological maturity, (2) high sucrose content in the stalk during grain filling, (3) busks and cobs with more water, sucrose and proteins, (4) high protein content in the grain. The high level of sucrose in the stalk at physiological maturity protects the plant from stalk rotting organisms.The delayed senescence phenotype depends on a major dominant gene, the same genetic factor which favours the accumulation of a high level of sucrose in the stalk.
A Dominant Gene for Male Sterility in Wheat
Authors: Bing‐Hua L. , Jing‐Yang D. 
Published: April 2006

AbstractA dominant gene inducing male sterility in wheat is described. It is located on the short arm of chromosme 4D with a recombination percentage of 31.16 with the centromere. The potential use of this allele in breeding and cytogenetic studies in both tetraploid and hexaploid with is discussed.