New Phytol：浙江农林吴刚教授团队揭示ABI5作用于miR159的下游，延缓拟南芥的营养阶段变化
营养发育是植物发育的一个关键阶段，受一个进化上保守的miR156-SPL途径调控。以前的研究表明，miR159可以阻止miR156的过度激活，从而调节拟南芥营养生长相变的时间。
然而，miR159是否整合到脱落酸（ABA）信号通路中以控制营养相的变化仍然是未知的，因为miR159在ABA反应中也起着重要的调节作用。
在这里，我们显示ABI5（ABA不敏感5）的表达，ABA信号通路中的一个关键调节因子，在功能丧失突变体miR159（mir159ab）中显著升高。
ABI5的功能丧失（ABI5）促进了幼年到成年的转变，而ABI5的过度表达在短日照条件下延迟了这种转变。
遗传分析表明，mir159ab对营养相变的影响是ABI5依赖性的。进一步的分析证实MYB33是miR159的一个主要靶点，它通过直接结合ABI5的启动子来促进ABI5的转录。ABI5在miR156上游发挥作用，通过影响miR156-SPL途径中的基因表达来促进幼年发育。
因此，我们的研究揭示了ABI5在植物营养发育中的新作用，并暗示了ABA信号在拟南芥营养发育中的作用。
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.
https://nph.onlinelibrary.wiley.com/doi/10.1111/nph.17371?af=R
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