血红素加氧酶HY1通过ABA信号途径调节拟南芥耐旱性的分子机理

Heme oxygenase/carbon monoxide (HO/CO) is a novel signal system proven recently in plants; and overexpression of Arabidopsis HO-1 (HY1) resulted in salt tolerance phenotype (Xie et al., Plant J, 2011). However, we recently found that the HY1 mutant hy1-100 exhibited drought tolerance phenotype, whereas opposite phenomenon were observed in HY1 overexpression line 35S:HY1-3, both of which were correlated with the ABA signalling. In this project, differentially expressed ABA signalling genes regulated by hy1 were investigated through RNA-Seq, and then verified by qPCR. We then generated multiple mutants by crossing HY1 and ABI4/3/5 mutants (including double and triple mutants of ABI4/3/5), and by the over-expressed HY1 in ABI4/3/5 mutants. Combined with the analysis of the differences of corresponding drought tolerance phenotypes and ABA responses, the interrelationship between HY1 and ABI signalling cascade (especially ABI4) involved in drought signal transduction was studied. Finally, by crossing double mutants of HY1 and up- and down-stream genes involved in ABI4 signalling, as well as the pharmacological and genetic analysis, important candidate components of ABI4 signalling modulated by HY1 were isolated and analyzed. Overall, above results will not only illustrate the interrelationship between HY1 and ABA signalling involved in drought tolerance, but also provide new ideas for the increase of crop yield.

血红素加氧酶（HO）/一氧化碳（CO）是最近新发现的信号系统，上调拟南芥HO1（HY1）表达能提高其耐盐性（Xie等，Plant J, 2011）。最近我们却发现，拟南芥HY1突变体hy1-100较野生型更耐旱，而HY1过表达株系（35S:HY1-3）更易脱水，上述现象与ABA信号有关。本课题将进一步通过转录组测序筛选并验证干旱下受HY1调控的ABA信号转导差异表达基因；构建HY1与ABI4/3/5突变体的多元突变体，并将HY1导入ABI4/3/5相关突变体，结合耐旱性和ABA应答的差异，以ABI4为重点研究HY1与ABI在干旱信号转导中的相互关系；构建ABI4信号通路上下游基因与HY1的双突变体，结合遗传学和药理学实验发掘受HY1影响的ABI4通路中的关键组分。上述结果不仅能阐明ABA信号途径介导HY1调节耐旱性的具体机制和调控模式，同时对提高农作物产量提供新的思路。

血红素加氧酶（HO）/一氧化碳（CO）是最近新发现的信号系统，上调拟南芥HO1（HY1）表达能提高其耐盐性。最近我们却发现，拟南芥HY1突变体hy1-100较野生型更耐旱，而HY1过表达株系（35S:HY1-3）更易脱水，上述现象与ABA信号有关。本课题进一步通过转录组测序筛选并验证干旱下受HY1调控的ABA信号转导差异表达基因，发现ABI4转录因子受HY1调控；HY1突变导致的拟南芥对ABA超敏感和耐旱表型能被ABI4突变所逆转，HY1突变体气孔关闭对ABA超敏感的表型也能被ABI4突变所回补。后续实验发现HY1-ABI4信号通过调控RbohD产生的ROS来控制气孔关闭。上述结果阐明了ABA信号途径中ABI4信号介导HY1调节耐旱性的调控模式，为提高农作物对干旱的适应能力提供了新的理论基础。相关的研究成果已被Plant Physiology、Functional Plant Biol、Acta Physiol Plant、植物生理学报、中国生物化学与分子生物学报发表或接收。