拟南芥赤霉素突变体ga4-1和gai-1营养生长时相转变研究  

Vegetative Phase Change of GA-related Mutants ga4-1 and gai-1 in Arabidopsis

作　　者：张冬野[1] 郭蕊[1] 刘唐婧君 王雪[1] 刘林[1] 龙鸿[1] 

机构地区：[1]天津农学院园艺园林学院,天津300384 [2]华中农业大学生命科技学院,武汉430070

出　　处：《沈阳农业大学学报》2016年第4期399-405,共7页Journal of Shenyang Agricultural University

基　　金：教育部留学回国人员基金项目(4002-082017)

摘　　要：高等植物营养生长经历了幼龄期(juvenile stage)和成熟期(adult stage)两个阶段,由幼龄期向成熟期的转变称为营养生长时相转变(vegetative phase change),这个转变受到包括植物激素(含赤霉素)在内的植物自身遗传和营养、光照等外界环境因子的共同作用,但其调控机制仍不清楚。本研究以2种作用于不同途径的拟南芥赤霉素相关突变体ga4-1和gai-1为材料,观察和记录了其营养生长时相转变的过程。结果表明,ga4-1和gai-1的生长周期均比野生型的延长,从叶片远轴面表皮毛的出现、莲座叶总数和生长速率、叶片长宽比等营养生长形态特征和茎尖分生组织解剖结构特征分析,ga4-1和gai-1突变体延迟了拟南芥营养生长时相转变。突变体由于GA运输、传递受到影响,活性GA降低,原套产生多层细胞较晚,原体和髓分生组织的细胞发育延迟,SAM(茎端分生组织,shoot apical meristem)高度h1(原套、原体细胞和髓分生组织高度)以及主轴高度h2(SAM及其下的分化细胞的高度总和)增长延迟,使得突变体莲座叶生长速率落后于野生型,叶片总数增多,营养生长时相转变延迟。此外,营养生长期间,突变体茎尖分生组织的高度均低于野生型,说明GA活性缺失造成茎尖发育的延缓。ga4-1和gai-1分别是拟南芥GA合成途径和信号转导途径的突变体,它们的突变导致拟南芥营养生长时相转变发生改变,说明GA作为调控植物生长发育的一种主要植物激素,参与了植物营养生长时相转变的调控,通过调控GA在茎端的活性,影响原套、原体和髓分生组织的发育、叶片总数和叶片生长速率,延迟了营养生长时相转变的发生。Higher plants undergo two developmental stages, juvenile stage and adult phase. The transition from juvenile to adultis termed vegetative phase change, which is controlled by distinct genetic circuits that integrate endogenous and environmentalcues. However, the mechanism of regulating vegetative phase change remains largely unknown. In this paper, vegetative phasechange regulated by gibberellin （GA） was analyzed using two loss-of-function mutants ga4-1 and gai-1. Our results showed thatthe growth period of ga4-1 and gai-1 was prolonged. Onset of abaxial trichomes of rosette leaves, total leaf number and growthrate, the length-to-width ratio of the lamina, and paraffin section of shoot apical meristems indicate that vegetative phase changein ga4-1 and gai-1 was delayed. In mutant plants, multi-layers of tunica cells were onset later, corpus and pith meristem zonedeveloped later due to the decrease of active GA. Height 1 of SAM （including tunica, corpus and pith meristem zone）, as wellas height 2 （height of the stem axis）, grew later than those in wild type plants, leading to the lower leaf growth rate and morerosette leaves. Thus, vegetative phase change was delayed in mutant plants. Moreover, the height of SAM were lower in mutantplants, suggesting a prolonged development of SAM due to the loss of activity of GA. Our results demonstrate that vegetativephase change in mutants of GA biosynthetic pathway （ga4 -1） and GA signal transduction pathway （gai -1） were delayed,suggesting that GA plays a key role in regulating plant vegetative phase change through affecting development of SAM （includingtunica, corpus and pith meristem zone）, total rosette leaves, and leaf growth rate.

关 键 词：营养生长时相转变 赤霉素 ga4-1 gai-1 拟南芥 

分 类 号：Q945.4[生物学—植物学]