Abscisic acid (ABA) is an important phytohormone controlling responses to abiotic stresses and is sensed by proteins from the PYR/PYL/RCAR family. To explore the genetic contribution of PYLs toward ABA-dependent and ABA-independent processes, we generated and characterized high-order Arabidopsis mutants with mutations in the PYL family. We obtained a pyl quattuordecuple mutant and found that it was severely impaired in growth and failed to produce seeds. Thus, we carried out a detailed characterization of a pyl duodecuple mutant, pyr1pyl1/2/3/4/5/7/8/9/10/11/12. The duodecuple mutant was extremely insensitive to ABA effects on seed germination, seedling growth, stomatal closure, leaf senescence, and gene expression. The activation of SnRK2 protein kinases by ABA was blocked in the duodecuple mutant, but, unexpectedly, osmotic stress activation of SnRK2s was enhanced. Our results demonstrate an important role of basal ABA signaling in growth, senescence, and abscission and reveal that PYLs antagonize ABA-independent activation of SnRK2s by osmotic stress.

中文翻译：

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PYL ABA受体的拟南芥十二指肠突变体揭示了ABA依赖性SnRK2活性的PYL抑制。

脱落酸（ABA）是控制非生物胁迫响应的重要植物激素，被PYR / PYL / RCAR家族的蛋白质所感知。为了探索PYL对ABA依赖和ABA独立过程的遗传贡献，我们生成并表征了PYL家族中具有突变的高阶拟南芥突变体。我们获得了一个pyl quatorordecuple突变体，发现该突变体严重损害了生长并且无法产生种子。因此，我们对pyl duodecuple突变体pyr1pyl1 / 2/3/4/5/7/8/9/10/11/12进行了详细的表征。duodecuple突变体对ABA对种子发芽，幼苗生长，气孔关闭，叶片衰老和基因表达的影响极为不敏感。在十二指肠突变体中，ABA激活了SnRK2蛋白激酶的激活，但出乎意料的是，SnRK2s的渗透胁迫激活增强。我们的结果证明了基础ABA信号传导在生长，衰老和脱落中的重要作用，并揭示了PYLs通过渗透胁迫拮抗SnRK2s的ABA非依赖性激活。