砂漠に生きる野生植物：有用遺伝子資源の探索と利用
明石 欣也
奈良先端大、バイオサイエンス研究科

Annual record yield, average yield, and yield losses due to diseases, insects andunfavorable physicochemical environments for major U.S. crops(Kg yield/Hectare)
040,000

80,000120,000

Sugar beet
PotatoBarleyOat

Annual record yield
Annual average yield
Yield loss（diseases）（insects）（weeds）（environmental stress）

SorghamSoybean
Wheat
Corn% avg
0204060

80

100

Boyer (1982) Science 218, 443-448

Survival strategies of xerophytes under water deficits
Hydrophyte
Mesophyte

PlantsAdapts to humid condition

Drought
escapeXerophyte

バオバウ

Drought
resistant

Short life cycle
Developmental plasticity

Drought avoidance
Efficient water uptake
Prevention of water loss

サボテン

Excess light
High temperaturestresses

Water storage

Wild watermelon

Desiccation tolerance
Vitrification
Efficient cellular
repair and recovery

Craterostigma
Resurrection plant

Wild Watermelon
Inhabit in the Kalahari Desert, Africa.
Thrives in the spring to summer.
Highly tolerant to drought andhigh light stresses.
Carries out C3-type photosynthesis.
Kalahari Desert (Botswana)

Wild watermelon and “Sun”
people in Kalahari Desert“Sun people” lives in the Kalahari Desert, Africa.
They use fruit extracts of wild watermelon as
major water resources for their living, such as
drinking, cooking, and washing their bodies.

Ikeya (1991) Kikan-minzokugaku、56:35-42

Free amino acid content(μmol/gFW)

Drought-induced accumulation ofcitrulline in the leaves of wild watermelon

N-acetylglutamate

Glutamate40

Citrulline
Arginine
Ornithine
Glutamate
Glutamine
Proline
AlanineGlycineSerineAspartate30
20100308Days under droughtN-acetylglutamate5’-phosphate
N-acetylglutamate5’-semialdehyde

Glutamine
Carbamoylphosphate

N-acetylornithine

Ornithine
Urea

Citrulline

Arginine
ArgininoSuccinateCitrulline is a potent scavenger for hydroxyl radicals

GlycinebetaineFormation of DHBA (% control)

1008060

Proline40
Mannitol200

Citrulline
02040

Solute concentration (mM)60

Second-order rate constants for the reactions
between hydroxyl radicals and various compounds

CompoundRate constant(M-1 s-1)

Concentrationin vivo(mM)Half-life ofhydroxyl radicals
generated in vivo(ns)Citrulline

3.9×109

200 - 300

0.59 - 0.89

Mannitol

2.1 × 109

100 - 320

1.0 - 3.3

Proline

5.4 × 108120 - 428

3.0 - 11

Glycine betaine

8.2 × 107

320 - 1,000

8.5 - 26

Ascorbic acidGlutathione

7.3 × 109
8.6 × 10925 - 50
1 - 4.5

1.9 - 3.8
18 - 80

Citrulline protects DNA from oxidative damages

H2O2Fe(II)Citrulline
(mM)

000

50 100 200

Damaged DNA(linear)
Intact DNA(supercoiled)野生スイカ・シトルリン

・ 天然成分・ 活性酸素ヒドロキシル・ラジカルの分解に優れる
・ 高い安全性
・ 光に対して安定で、持続性に優れる

化粧品

医薬品
構成成分

機能性食品・
食品添加物

スキン・ケア（しみ・そばかす・しわ・アトピー性皮膚炎）

活性酸素傷害の緩和

食品の保存性の向上
体内環境の改善10カラハリ・スイカの果実☆ シトルリン高含量、☆ 水溶性炭水化物が多いが、甘味料を含まず、低カロリー☆ 抗酸化能力に極めて優れている☆ 水分の保湿効果が高い

カラハリ・スイカの保湿効果
1080２５％60

果汁

水00.3 mM

水0５％果汁20(0.3 mM
シトルリンに相当)

5５％グリセリン40

試料滴下1時間後の水分残存量(%cont)

100

シトルリン

モニター試薬・サリチル酸の酸化抑制率(%cont)カラハリ・スイカの抗酸化効果

11

特許：特願2004-135241、野生スイカ抽出物を含有する活性酸素消去剤ならびに保湿剤Roots of the Desert Plants

Citrullus

Wickens (1998)

Fold increase
1 day 3 days

IE01 1.7
IE03 2.3
IE04 1.6
IE05 1.6
IE08 4.8
IE09 1.3
IE10 2.3
IE13 34.6
IE14 3.7
IE17 1.4
IE21 2.3
IE22 2.0
IE24 2.3
IE38 2.7
IE40 14.8
IE42 1.2IE43 2.5
IE46 1.8
IE50 26.8
IE53 1.8
IE54 1.7
IE57 66.6
IE59 1.3
IE60 1.5
IE64 1.5
IE67 1.4
IE71 2.7
IE77 2.0Annotation

1.4 aconitase
0.9 alkaline α galactosidase 21.6 methionine synthase
2.7 α-mannosidase
1.3 UDP-sugar pyrophospharylase
1.1 NADP-malic enzyme
0.9 NADP-malic enzyme
11.6 cytosolic phosphoglucomutase
4.4 T-complex protein 1, ETA subunit
0.5 Hsp 901.0 ferric leghemoglobin reductase
1.6 UDP-glucose 6-dehydrogenase
1.0 hypothetical protein
4.5 ubiquitin family protein
0.9 glutamine synthetase
1.6 peroxidase
3.8 peroxidase
1.5 actin
2.6 α-tubulin
3.3 unknown protein
0.8 putative elongation factor 2
0.3 sec13-like protein
2.2 cysteine protease CP1
1.7 caffeoyl-CoA O-methyltransferase
1.9 rubber elongation factor
1.9 cysteine protease
5.9 cytosolic triosephosphate isomerase
3.2 triose phosphate isomerase

Early-induced
Cell division
Rootmorphogenesis
C/N metabolism
Protein levelNo.

Drought-induced proteinsin the roots

Mixed-type
Protease
Antioxidativeprotein

Later-induced
Molecularchaperone
Lignin synthesis
Drought stress progession

Yoshimura et al (2008) Plant Cell Physiol

Jatropha curcas L.
▪ A member of the Euphorbia family▪ Originated from Central America▪ Relatively resistant to drought▪ Grows well in marginal/poor soils▪ Optimal annual temperature and precipitation:
20-28℃ and 480-2400 mm or more
▪ Grows relatively quickly, and produces high yield of seeds(~5 tons /ha/year)▪ Seeds contain large amount of oils (30-40%)

Genome engineering
Transgenic selection
Functional analyses

Chloroplast engineering
Processing/ Marketing

Elite germline selection
Assessment in arid areas
The Department of Agricultural Research
Ministry of Agriculture, Botswana

Elite germline selection
Physiological analyses
Field assessment
Elite germline selection
Assessment in tropics

JST/NSF Jatropha PJ
Chloroplast
Transformation
Technology

タバコ葉緑体ゲノムへのラン藻FBP/SBPase遺伝子導入による光合成と生産性の向上
学会発表：３月末の農芸化学会大会
出願番号：特願２００４?５９５１３
出願日：平成１６年３月３日

葉緑体ゲノムへのFBP/SBPase遺伝子導入

Improved
Photosynthesis

High light/droughttolerance

Molecular
Breeding ofStressTolerance

Improvement ofroot growth via
gene transfer

22

光合成速度（µmol CO2 m-2 s-1)）

Fortification of
Photosynthetic
activity via genetransfer

RuBisCOの活性化

20*
*

1816*
*

1412*
*

10*
*
*

8*
*

*

*
*
*

*
*

*
*

*

*

野生型タバコの光合成

64
20-20

2 00

4 00

6 00

8 00

1 ,0001,2 001,400

1 ,600

光強度 (µmol photons m-2 s-1)

野生型タバコ

Optimization ofcultivation

葉緑体工学を施したタバコ

Genes for:Photosynthesis
Root growth
Oil synthesis
Stress tolerance

Geneticallymodified
Jatropha withHigh Productivity
Productof
NBB

乾燥BDF潅水

ProductofNBB

BDFJatropha plants

NBB

BDF