Table1.xls

Defects in RNA processing and degradation pathways often lead to developmental abnormalities, impaired hormonal signaling and altered resistance to abiotic and biotic stress. Here we report that components of the 5′-3′ mRNA decay pathway, DCP5, LSM1-7 and XRN4, contribute to a proper response to a key plant hormone abscisc acid (ABA), albeit in a different manner. Plants lacking DCP5 are more sensitive to ABA during germination, whereas lsm1a lsm1b and xrn4-5 mutants are affected at the early stages of vegetative growth. In addition, we show that DCP5 and LSM1 regulate mRNA stability and act in translational repression of the main components of the early ABA signaling, PYR/PYL ABA receptors and SnRK2s protein kinases. mRNA decapping DCP and LSM1-7 complexes also appear to modulate ABA-dependent expression of stress related transcription factors from the AP2/ERF/DREB family that in turn affect the level of genes regulated by the PYL/PYR/RCAR-PP2C-SnRK2 pathway. These observations suggest that ABA signaling through PYL/PYR/RCAR receptors and SnRK2s kinases is regulated directly and indirectly by the cytoplasmic mRNA decay pathway.

RNA加工及降解途径中的缺陷往往导致发育异常、激素信号传导受损以及抗非生物和生物胁迫能力的改变。本研究报告指出，5'-3' mRNA降解途径的组成部分，包括DCP5、LSM1-7和XRN4，对植物激素脱落酸（ABA）的适当响应起到关键作用，尽管其作用方式各异。缺乏DCP5的植物在萌发期间对ABA更为敏感，而lsm1a、lsm1b和xrn4-5突变体在营养生长的早期阶段受到影响。此外，本研究还表明，DCP5和LSM1调控mRNA的稳定性，并在脱落酸早期信号传导主要成分，即PYR/PYL ABA受体和SnRK2蛋白激酶的翻译抑制中发挥作用。mRNA去帽的DCP和LSM1-7复合体似乎还调节ABA依赖性表达应激相关转录因子，这些转录因子属于AP2/ERF/DREB家族，进而影响受PYL/PYR/RCAR-PP2C-SnRK2途径调控的基因水平。这些观察结果提示，ABA通过PYL/PYR/RCAR受体和SnRK2激酶的信号传导受到细胞质mRNA降解途径的直接和间接调控。