Lin Jian-Hui, Liu Zi-Guang, Zhang Nan, Yan Rong, Zhang Nan, He Xin-Miao, Wang Wen-Tao, Liu Di, Wu Juan
College of Life Sciences, Northeast Forestry University, Key Laboratory of Northeast Salinity and Vegetation Restoration and Reconstruction, Ministry of Education, Harbin 150040, China.
Institute of Animal Husbandry, Heilongjiang Academy of Agricultural Sciences, Key Laboratory of Combination of Planting and Breeding, Ministry of Agriculture and Rural Affairs, Harbin 150028, China.
Yi Chuan. 2021 Sep 20;43(9):901-909. doi: 10.16288/j.yczz.21-199.
Abscisic acid-insensitive 5 (ABI5) is a basic leucine zipper (bZIP) transcription factor that is abundantly expressed in seeds. It plays a central role in regulating the abscisic acid (ABA) signal of seed germination and early seedling growth. Brassinosteroid (BR) is a new type of plant endogenous hormone, which has many physiological functions such as regulating plant growth and development and response to adversity stress. It has recently been discovered that under brassinolide stress, BIN2 (BRASSINOSTEROID INSENSITIVE2) and BES1 (BRI1-EMS-SUPPRESSOR 1) in the BR signaling pathway can inhibit the expression of ABI5 and promote Arabidopsis thaliana seed germination. In order to further explore the function of ABI5 under BR stress, this study analyzed the ABI5 expression characteristics during seed germination, identified Arabidopsis ABI5 gene deletion mutant abi5-1 and analyzed its function under BR stress, the results of which indicated that ABI5 was abundantly expressed in Arabidopsis dry seeds and responded to BR stress during germination. Under normal conditions, there was no significant difference between the hypocotyls of abi5-1 and wild-type seedlings; but under BR stress, the hypocotyls of abi5-1 seedlings were significantly longer than those of wild-type seedlings. These results reveal that ABI5 regulates the growth of Arabidopsis hypocotyls under BR stress, thereby providing a basis for in-depth understanding of the molecular mechanism of ABI5 regulation on plant development.
脱落酸不敏感5（ABI5）是一种在种子中大量表达的碱性亮氨酸拉链（bZIP）转录因子。它在调节种子萌发和幼苗早期生长的脱落酸（ABA）信号中起核心作用。油菜素内酯（BR）是一种新型植物内源激素，具有调节植物生长发育和应对逆境胁迫等多种生理功能。最近发现，在油菜素内酯胁迫下，BR信号通路中的BIN2（油菜素内酯不敏感2）和BES1（BRI1-EMS抑制因子1）可以抑制ABI5的表达并促进拟南芥种子萌发。为了进一步探究BR胁迫下ABI5的功能，本研究分析了种子萌发过程中ABI5的表达特征，鉴定了拟南芥ABI5基因缺失突变体abi5-1并分析了其在BR胁迫下的功能，结果表明ABI5在拟南芥干种子中大量表达，并在萌发过程中对BR胁迫作出响应。在正常条件下，abi5-1和野生型幼苗的下胚轴没有显著差异；但在BR胁迫下，abi5-1幼苗的下胚轴明显长于野生型幼苗。这些结果揭示了ABI5在BR胁迫下调节拟南芥下胚轴的生长，从而为深入了解ABI5调控植物发育的分子机制提供了依据。
