School of Life Sciences and Division of Molecular & Cell Biophysics, Hefei National Science Center for Physical Sciences at the Microscale, University of Science and Technology of China, The Innovation Academy of Seed Design, Chinese Academy of Sciences, Hefei, Anhui Province, 230027, China.
New Phytol. 2020 Jan;225(2):835-847. doi: 10.1111/nph.16172. Epub 2019 Oct 14.
Seed germination is a crucial transition point in plant life and is tightly regulated by environmental conditions through the coordination of two phytohormones, gibberellin and abscisic acid (ABA). To avoid unfavorable conditions, plants have evolved safeguard mechanisms for seed germination. The present contribution reports a novel function of the Arabidopsis MCM1/AGAMOUS/DEFICIENS/SRF(MADS)-box transcription factor ARABIDOPSIS NITRATE REGULATED 1 (ANR1) in seed germination. ANR1 knockout mutant is insensitive to ABA, salt and osmotic stress during the seed germination and early seedling development stages, whereas ANR1-overexpressing lines are hypersensitive. ANR1 is responsive to ABA and abiotic stresses and upregulates the expression of ABA Intolerant (ABI)3 to suppress seed germination. ANR1 and ABI3 have similar expression pattern during seed germination. Genetically, ABI3 acts downstream of ANR1. Chromatin immunoprecipitation and yeast-one-hybrid assays showed that ANR1 could bind to the ABI3 promoter to regulate its expression. In addition, ANR1 acts synergistically with AGL21 to suppress seed germination in response to ABA as evidenced by anr1 agl21 double mutant. Taken together, the results herein demonstrate that the ANR1 plays an important role in regulating seed germination and early postgermination growth. ANR1 and AGL21 together constitutes a safeguard mechanism for seed germination to avoid unfavorable conditions.
种子萌发是植物生命中的一个关键转折点，它通过两种植物激素——赤霉素和脱落酸（ABA）的协调，受到环境条件的严格调控。为了避免不利条件，植物进化出了种子萌发的保护机制。本研究报告了拟南芥 MCM1/AGAMOUS/DEFICIENS/SRF（MADS）-box 转录因子 ARABIDOPSIS NITRATE REGULATED 1（ANR1）在种子萌发中的一个新功能。ANR1 敲除突变体对 ABA、盐和渗透胁迫在种子萌发和幼苗早期发育阶段不敏感，而 ANR1 过表达系则表现出超敏性。ANR1 对 ABA 和非生物胁迫有反应，并上调 ABA 不耐受（ABI）3 的表达以抑制种子萌发。ANR1 和 ABI3 在种子萌发过程中有相似的表达模式。遗传上，ABI3 位于 ANR1 的下游。染色质免疫沉淀和酵母单杂交实验表明，ANR1 可以结合 ABI3 启动子来调节其表达。此外，ANR1 与 AGL21 协同作用，通过 anr1 agl21 双突变体证明其能响应 ABA 抑制种子萌发。综上所述，这些结果表明，ANR1 在调节种子萌发和早期萌发后生长中起着重要作用。ANR1 和 AGL21 一起构成了种子萌发的保护机制，以避免不利条件。
