State Key Laboratory of Subtropical Silviculture, School of Agriculture and Food Sciences, Zhejiang Agriculture and Forestry University, Hangzhou, 311300, China.
New Phytol. 2021 Jul;231(1):339-350. doi: 10.1111/nph.17371. Epub 2021 Apr 29.
Vegetative development constitutes a critical phase in plant development, and it is regulated by an evolutionarily conserved miR156-SPL pathway. Previous studies have shown that miR159 acts to prevent the hyperactivation of miR156 to regulate the timing of vegetative phase change in Arabidopsis. However, whether miR159 integrates into the abscisic acid (ABA) signaling pathway to control vegetative phase change remains unexplored, since miR159 also plays an important regulatory role in ABA response. Here, we show that the expression of ABI5 (ABA INSENSITIVE5), a crucial regulator in the ABA signaling pathway, is significantly elevated in the loss-of-function mutant of miR159 (mir159ab). Loss of function in ABI5 (abi5) promotes juvenile-to-adult transition, whereas overexpression of ABI5 delays this transition under short-day conditions. Genetic analyses indicated that the effect of mir159ab on vegetative phase change is ABI5 dependent. Further analysis confirmed that MYB33, a major target of miR159, promotes the transcription of ABI5 by directly binding to its promoter. ABI5 functions upstream of miR156 to promote juvenile development by affecting the expression of genes in the miR156-SPL pathway. Therefore, our study uncovers a new role of ABI5 in vegetative development in plants, and implies a role of ABA signaling in vegetative development in Arabidopsis.
营养生长是植物发育的关键阶段，它受到一个进化保守的 miR156-SPL 途径的调控。以前的研究表明，miR159 可以防止 miR156 的过度激活，从而调节拟南芥营养生长阶段的转变。然而，miR159 是否整合到脱落酸（ABA）信号通路中以控制营养生长阶段的转变仍未被探索，因为 miR159 在 ABA 反应中也发挥着重要的调节作用。在这里，我们发现，在 miR159 的功能丧失突变体（mir159ab）中，ABA 信号通路中的关键调节因子 ABI5（ABA INSENSITIVE5）的表达显著升高。ABI5 的功能丧失（abi5）促进了从幼年期到成年期的转变，而在短日照条件下，ABI5 的过表达则延迟了这种转变。遗传分析表明，mir159ab 对营养生长阶段的转变的影响依赖于 ABI5。进一步的分析证实，miR159 的主要靶标 MYB33 通过直接结合其启动子，促进 ABI5 的转录。ABI5 在 miR156-SPL 途径的基因表达中起作用，通过影响 miR156-SPL 途径的基因表达来促进幼年期发育。因此，我们的研究揭示了 ABI5 在植物营养生长发育中的一个新作用，并暗示了 ABA 信号在拟南芥营养生长发育中的作用。
