Kasera Mritunjay, Ceciliato Paulo H O, Lopez Bryn N K, Hauser Felix, Gendron Joshua M, Schroeder Julian I
Cell and Developmental Biology Department, University of California San Diego, La Jolla, CA, USA.
Molecular, Cellular & Developmental Biology, Yale University, New Haven, CT, USA.
Philos Trans R Soc Lond B Biol Sci. 2025 May 29;380(1927):20240233. doi: 10.1098/rstb.2024.0233.
Large gene families and the frequent overlapping functions of homologous genes remain a major challenge for functional forward genetic screens in plants. The recent development of homology-based gene silencing using computationally generated artificial microRNAs (amiRNAs) has been demonstrated to be a promising tool for unbiased functional genomics in plants by circumventing redundancies and lethality. In this study, through a forward genetics screen, we isolated an abscisic acid (ABA)-insensitive amiRNA line targeting five previously uncharacterized () genes. Notably, a triple mutant in the identified genes , and (), that are expressed in germinating seeds, exhibited insensitivity in ABA inhibition of seed germination. In contrast, this ABA insensitivity was not observed in a double mutant of two genes and . Further investigation of the FIA1 interactome using F-box decoy lines revealed the gibberellin (GA)-responsive GASA1 protein that has been reported to encode a small stress signalling peptide as an interacting partner. We found that ABA promoted the ubiquitination of GASA1 in , leading to its degradation via the 26S proteasome pathway. Together, our study reveals that ABA represses seed germination through FIA proteins and regulates the FIA interactor, GA-responsive GASA1.This article is part of the theme issue 'Crops under stress: can we mitigate the impacts of climate change on agriculture and launch the 'Resilience Revolution'?'.
大型基因家族以及同源基因频繁的重叠功能仍然是植物正向遗传学功能筛选面临的主要挑战。最近，利用计算机生成的人工微小RNA（amiRNA）进行基于同源性的基因沉默技术得到了发展，该技术通过规避基因冗余和致死性，已被证明是一种用于植物无偏差功能基因组学研究的有前途的工具。在本研究中，通过正向遗传学筛选，我们分离出了一个脱落酸（ABA）不敏感的amiRNA株系，该株系靶向五个先前未表征的（）基因。值得注意的是，在已鉴定的、在萌发种子中表达的基因、和（）的三突变体中，ABA对种子萌发的抑制作用表现出不敏感性。相比之下，在两个基因和的双突变体中未观察到这种ABA不敏感性。使用F-box诱饵株系对FIA1相互作用组进行的进一步研究揭示，赤霉素（GA）响应性GASA1蛋白（据报道其编码一种小的胁迫信号肽）是其相互作用伴侣。我们发现ABA促进了GASA1在中的泛素化，导致其通过26S蛋白酶体途径降解。总之，我们的研究表明ABA通过FIA蛋白抑制种子萌发，并调节FIA相互作用蛋白、GA响应性GASA1。本文是主题为“胁迫下的作物：我们能否减轻气候变化对农业的影响并发起‘抗逆革命’？”的一部分。
