STE20L4促进拟南芥下胚轴伸长的机制研究  

Mechanism Study of STE20L4 in Promoting Hypocotyl Elongation of Arabidopsis thaliana

作　　者：佘玉婷 丁勇[1] SHE Yuting;DING Yong(School of Life Sciences,University of Science and Technology of China,Hefei,Anhui 230027,China)

机构地区：[1]中国科学技术大学生命科学学院,安徽合肥230027

出　　处：《热带作物学报》2022年第6期1144-1151,共8页Chinese Journal of Tropical Crops

基　　金：国家自然科学基金项目(No.32000242)。

摘　　要：下胚轴伸长是高等植物进行正常生命活动的保障,下胚轴的伸长协助植株破土而出并由异养转变为自养生长。本研究通过对一系列拟南芥突变体材料进行下胚轴观察,鉴定到一个具有短下胚轴的突变体ste20l4,并对其调控下胚轴伸长的分子机制进行初步探索。结果表明:STE20L4编码与酵母中STE20同源的丝裂原活化蛋白激酶,在MAPK级联信号通路中作为MAP4K激活下游的MAP3K。基因型鉴定和半定量结果显示,ste20l4-1、ste20l4-2均为功能缺失的突变体。通过表型观察,ste20l4突变体无论在长日照(16 h光照/8 h黑暗)、短日照(8 h光照/16 h黑暗)及黑暗(24 h黑暗)条件下与野生型相比均呈现出短的下胚轴。细胞学结果显示,突变体ste20l4短的下胚轴是由于其细胞长度的变短而不是细胞数目的变化导致的。植物激素赤霉素可促进下胚轴的伸长,对其处理的敏感性可作为是否参与GA信号转导途径的判断方法。在不同梯度浓度的GA处理(0、0.5、1、2、5μmol/L)下,ste20l4突变体与野生型相比下胚轴伸长作用不明显。多效唑(PAC)是内源GA合成的抑制剂,随着不同梯度浓度的PAC处理(0、0.01、0.02、0.05、0.1、0.2、0.5μmol/L),ste20l4突变体下胚轴伸长的抑制作用相对于野生型不明显。上述生理学结果表明,STE20L4参与到GA信号转导通路中调控拟南芥下胚轴的生长发育。将STE20L4蛋白与荧光标签融合后转染烟草或拟南芥原生质体观察其亚细胞定位,结果表明STE20L4在细胞膜和细胞质中均有表达。对野生型、ste20l4突变体中进行一系列GA下游与下胚轴伸长相关基因的RT-qPCR检测,结果表明XTH17、EXP2、PRE1、PIF4、YUC2和SAUR19基因的转录水平在ste20l4突变体中明显下调,即STE20L4可能通过间接调控这些下游基因的表达参与下胚轴的伸长。综上,STE20L4参与GA信号转导通路,且通过促进GA下游下胚轴伸长相关基因的表达调控下胚轴的伸Hypocotyl elongation assists plants to break through the soil and changes from heterotrophic to self-sustaining,which is the guarantee of normal life activities of higher plants.In this study,a mutant with shorter hypocotyl was identified by observing the hypocotyl of a series of Arabidopsis mutants in our laboratory and the molecular mechanism of regulating hypocotyl elongation was preliminarily explored.STE20L4,as a MAP4K,encodes a mitosis-activated protein kinase homologous to STE20 in yeast and activates downstream MAP3K in the MAPK cascade signaling pathway.Genotyping identification and semi-quantitative results showed that ste20l4-1 and ste20l4-2 were mutants with loss of function.Through phenotype observation,the ste20l4 mutant shows a short hypocotyl either in long daylight(16 h light/8 h dark),short daylight(8 h light/16 h dark)and dark(24 h dark)conditions compared with the wild type.Cytological results showed that short hypocotyl of ste20l4 mutants were due to a shortening of cell length rather than a change in cell number.The plant hormone gibberellin can promote the elongation of the hypocotyl and the sensitivity to its treatment can be used as a method of judging whether to participate in the GA signal transduction pathway.Under different gradient concentrations GA(0,0.5μmol/L,1μmol/L,2μmol/L and 5μmol/L)treatment,the hypocotyl elongation of ste20l4 mutants were not significant compared with the wild type.Paclobutrazol(PAC)is an inhibitor of endogenous GA synthesis,with gradient concentrations PAC(0,0.01μmol/L,0.02μmol/L,0.05μmol/L,0.1μmol/L,0.2μmol/L,and 0.5μmol/L)processing,the inhibition of hypocotyl elongation in mutants were also less pronounced than wild type.The above physiological results show that STE20L4 is involved in regulating the growth and development of hypocotyl in the GA signal transduction pathway.After fusing the protein of STE20L4 with fluorescent tags,we transfected them into tobacco and Arabidopsis protoplasts to observe subcellular localization,the results showed th

关 键 词：STE20L4 下胚轴 GA PAC 细胞长度 

分 类 号：S565.9[农业科学—作物学]