Division of Plant physiology, ICAR-Indian Agricultural Research Institute, New Delhi, India.
Department of Botany, Bharthidasan University, Tiruchirappalli, Tamil Nadu, India.
J Exp Bot. 2021 Feb 24;72(4):1411-1431. doi: 10.1093/jxb/eraa509.
Abscisic acid (ABA) is a key regulator of plant development and stress tolerance. Here we report functional validation of the ABA receptor OsPYL6 by constitutive and stress-inducible overexpression and RNAi silencing, in an indica rice cultivar 'Pusa Sugandh 2'. Overexpression of OsPYL6 conferred ABA hypersensitivity during germination and promoted total root length. Overexpression and RNAi silencing of OsPYL6 resulted in enhanced accumulation of ABA in seedlings under non-stress conditions, at least, in part through up-regulation of different 9-cis epoxycarotenoid dioxygenase (NCED )genes. This suggests that PYL6 expression is crucial for ABA homeostasis. Analysis of drought tolerance of OsPYL6 transgenic and wild type plants showed that OsPYL6 overexpression enhanced the expression of stress-responsive genes and dehydration tolerance. Transgenic rice plants overexpressing OsPYL6 with AtRD29A (Arabidopsis thaliana Responsive to Dehydration 29A) promoter also exhibited about 25% less whole plant transpiration, compared with wild type plants under drought, confirming its role in activation of dehydration avoidance mechanisms. However, overexpression of PYL6 reduced grain yield under non-stress conditions due to reduction in height, biomass, panicle branching and spikelet fertility. RNAi silencing of OsPYL6 also reduced grain yield under drought. These results showed that rice OsPYL6 is a key regulator of plant development and drought tolerance, and fine-tuning of its expression is critical for improving yield and stress tolerance.
脱落酸（ABA）是植物发育和应激耐受的关键调节剂。在这里，我们通过组成型和应激诱导的过表达和 RNAi 沉默，在籼稻品种 'Pusa Sugandh 2' 中报告了 ABA 受体 OsPYL6 的功能验证。OsPYL6 的过表达在萌发过程中赋予 ABA 超敏性，并促进总根长。OsPYL6 的过表达和 RNAi 沉默导致非胁迫条件下幼苗中 ABA 的积累增加，至少部分是通过上调不同的 9-顺式环氧类胡萝卜素双加氧酶（NCED）基因实现的。这表明 PYL6 的表达对于 ABA 平衡至关重要。对 OsPYL6 转基因和野生型植物耐旱性的分析表明，OsPYL6 的过表达增强了应激响应基因的表达和耐旱性。过表达 OsPYL6 与 AtRD29A（拟南芥响应脱水 29A）启动子的转基因水稻植物在干旱条件下也表现出约 25%的全株蒸腾减少，与野生型植物相比，证实了其在激活脱水回避机制中的作用。然而，由于高度、生物量、穗分枝和小穗育性降低，PYL6 的过表达在非胁迫条件下降低了粒产量。OsPYL6 的 RNAi 沉默也降低了干旱条件下的粒产量。这些结果表明，水稻 OsPYL6 是植物发育和耐旱性的关键调节剂，其表达的精细调控对于提高产量和应激耐受性至关重要。
