欧亚国际

来自以色列的科学利用Plantarray高通量植物生理表型平台和植物逆境生物学生理研究平台发表了题为Inhibition of gibberellin accumulation by water deficiency promotes fast and long-term 'drought avoidance' responses in tomato的文章。目前利用该系统已经在主流期刊上发表了近40篇文章，典型客户包括以色列希伯来大学和荷兰瓦赫宁根大学等等。

Inhibition of gibberellin accumulation by water deficiency promotes fast and long-term 'drought avoidance' responses in tomato

植物通过气孔关闭和抑制冠层生长来减少蒸腾作用，以避免干旱期间的脱水。虽然脱落酸（ABA）在“避免干旱”中起主要作用，但先前的研究表明赤霉素（GA）也可能参与其中。我们在番茄（Solanum lycopersicum）中发现，缺水抑制GA生物合成基因GA20 oxidase1（GA20ox1）和GA20ox2的表达，并在叶片和保卫细胞中诱导GA失活基因GA2ox7，导致生物活性GA水平降低。GA代谢的干旱调节由ABA依赖和独立的途径以及转录因子脱水反应元件结合（DREB）TINY1介导。由于冠层面积较小，GA20ox1和GA20ox2的突变减少了水分损失。另一方面，GA2ox7的缺失不影响叶片大小，但减弱了气孔对水分亏缺的响应；在土壤脱水过程中，ga2ox7植物比WT更晚关闭气孔并减少蒸腾作用，表明ga2ox7气孔对土壤脱水不敏感。总之，这些结果表明，干旱诱导的保卫细胞中GA失活有助于土壤脱水早期的气孔关闭，而叶片中GA合成的抑制主要促进冠层生长的长期减少，从而减少蒸腾面积。

ABSTRACT

Plants reduce transpiration to avoid dehydration during drought episodes by stomatal closure and inhibition of canopy growth. While abscisic acid (ABA) has a primary role in 'drought avoidance', previous studies suggest that gibberellin (GA), might also be involved. Here we show in tomato (Solanum lycopersicum) that shortage of water inhibited the expression of the GA biosesynthesis genes GA20 oxidase1 (GA20ox1) and GA20ox2 and induced the GA-deactivating gene GA2ox7 in leaves and guard cells, resulting in reduced bioactive GA levels. Drought regulation of GA metabolism was mediated by ABA-dependent and independent pathways, and by the transcription factor DEHYDRATION RESPONSIVE ELEMENT BINDING (DREB), TINY1. Mutations in GA20ox1 and GA20ox2 reduced water loss due to the smaller canopy area. On the other hand, loss of GA2ox7 did not affect leaf size, but attenuated stomatal response to water deficiency; during soil dehydration, ga2ox7 plants closed their stomata and reduced transpiration later than WT, suggesting that ga2ox7 stomata are hyposensitive to soil dehydration. Together, the results suggest that drought-induced GA deactivation in guard cells contributes to stomatal closure at the early stages of soil dehydration, whereas inhibition of GA synthesis in leaves promotes mainly the long-term reduction in canopy growth to reduce transpiration area.