Steber C M, Cooney S E, McCourt P
Department of Botany, University of Toronto, Toronto, Ontario M5S 3B2, Canada.
Genetics. 1998 Jun;149(2):509-21. doi: 10.1093/genetics/149.2.509.
Seed dormancy and germination in higher plants are partially controlled by the plant hormones abscisic acid (ABA) and gibberellic acid (GA). ABA establishes dormancy during embryo maturation, whereas GA breaks dormancy and induces germination. Previous attempts to identify GA response genes were confounded because GA mutants are not expected to germinate and, unlike GA auxotrophs, should fail to be rescued by exogenous GA. Here, we describe a screen for suppressors of the ABA-insensitive mutant ABI1-1 that enriches for GA auxotrophs and GA-insensitive mutants. The vast majority (76%) of the suppressors of ABI1-1 strongly resemble GA auxotrophs in that they are severely dwarfed and have dark green foliage and flowers with underdeveloped petals and stamen. Three isolates were alleles of the GA auxotroph ga1. The remaining severe dwarves were not rescued by GA and belong to a single complementation group that we designate sly1 (Sleepy 1). The alleles of sly1 identified are the first recessive GA-insensitive mutations to reflect the full spectrum of GA-associated phenotypes, including the failure to germinate in the absence of the ABI1-1 lesion. Thus, we postulate that SLY1 is a key factor in GA reception.
高等植物中的种子休眠与萌发部分受植物激素脱落酸（ABA）和赤霉素（GA）的调控。ABA在胚胎成熟过程中建立休眠，而GA则打破休眠并诱导萌发。先前鉴定GA反应基因的尝试受到了干扰，因为GA突变体预期不会萌发，并且与GA营养缺陷型不同，外源GA无法挽救它们。在此，我们描述了一种针对ABA不敏感突变体ABI1-1的抑制子筛选方法，该方法可富集GA营养缺陷型和GA不敏感突变体。ABI1-1的绝大多数抑制子（76%）与GA营养缺陷型极为相似，表现为严重矮化，叶片和花朵深绿，花瓣和雄蕊发育不全。三个分离株是GA营养缺陷型ga1的等位基因。其余的严重矮化植株不能被GA挽救，属于一个单一的互补群，我们将其命名为sly1（嗜睡1）。所鉴定的sly1等位基因是首批隐性GA不敏感突变，反映了GA相关表型的全貌，包括在没有ABI1-1损伤的情况下无法萌发。因此，我们推测SLY1是GA信号接收中的关键因子。
