Accumulation of trehalose within transgenic chloroplasts confers drought tolerance
Accumulation of trehalose within transgenic chloroplasts confers drought tolerance
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DOI：
10.1023/a:1022100404542
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发表时间：
2003-01-01
影响因子：
3.1
通讯作者：
Daniell, H
中科院分区：
文献类型：
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作者：
Lee, SB;Kwon, HB;Daniell, H
将酵母海藻糖磷酸合酶 (TPS1) 基因引入烟草叶绿体或核基因组中以研究所得表型。 PCR和Southern印迹证实TPS1稳定整合到T-1、T-2和T-3转基因植物的叶绿体基因组中。转基因植物的 Northern 印迹分析表明，叶绿体转化体的 TPS1 转录本表达量是现存最好的核转基因植物的 169 倍。尽管叶绿体和核转基因植物都显示出显着的TPS1酶活性，但在T-0/T-1核转基因植物中没有观察到显着的海藻糖积累，而叶绿体转基因植物显示出比存活最好的核转基因植物高15-25倍的海藻糖积累。即使显示少量海藻糖积累的核转基因植物（T-0）也显示出发育不良的表型、不育和其他多效性效应，而叶绿体转基因植物（T-1、T-2、T-3）则显示出正常生长并且没有多效性效应。转基因叶绿体类囊体膜在渗透胁迫下表现出高度完整性，即使在 6% PEG 中生长时叶绿素的保留也证明了这一点，而未转化植物中的叶绿体则被漂白。干燥 7 小时后，叶绿体转基因幼苗（T-1、T-3）成功再水化，而对照植物死亡。对照植物和转基因植物在脱水过程中失水没有差异，但转基因植物的脱水叶子（24天未浇水）在补水后恢复变绿，而对照叶子则变干。这些观察结果表明海藻糖通过保护生物膜而不是调节水势发挥作用。为了防止杂草的耐旱性状和相关作物的相关多效性状的逃逸，可能需要通过叶绿体基因组而不是核基因组对作物进行工程改造以获得耐旱性。
Yeast trehalose phosphate synthase (TPS1) gene was introduced into the tobacco chloroplast or nuclear genomes to study resultant phenotypes. PCR and Southern blots confirmed stable integration of TPS1 into the chloroplast genomes of T-1, T-2 and T-3 transgenic plants. Northern blot analysis of transgenic plants showed that the chloroplast transformant expressed 169-fold more TPS1 transcript than the best surviving nuclear transgenic plant. Although both the chloroplast and nuclear transgenic plants showed significant TPS1 enzyme activity, no significant trehalose accumulation was observed in T-0/T-1 nuclear transgenic plants whereas chloroplast transgenic plants showed 15-25 fold higher accumulation of trehalose than the best surviving nuclear transgenic plants. Nuclear transgenic plants (T-0) that showed even small amounts of trehalose accumulation showed stunted phenotype, sterility and other pleiotropic effects whereas chloroplast transgenic plants (T-1, T-2, T-3) showed normal growth and no pleiotropic effects. Transgenic chloroplast thylakoid membranes showed high integrity under osmotic stress as evidenced by retention of chlorophyll even when grown in 6% PEG whereas chloroplasts in untransformed plants were bleached. After 7 hr drying, chloroplast transgenic seedlings (T-1, T-3) successfully rehydrated while control plants died. There was no difference between control and transgenic plants in water loss during dehydration but dehydrated leaves from transgenic plants (not watered for 24 days) recovered upon rehydration turning green while control leaves dried out. These observations suggest that trehalose functions by protecting biological membranes rather than regulating water potential. In order to prevent escape of drought tolerance trait to weeds and associated pleiotropic traits to related crops, it may be desirable to engineer crop plants for drought tolerance via the chloroplast genome instead of the nuclear genome.