阿拉伯芥兩個富含甘胺酸蛋白質在熱逆境及生長發育時期之功能性研究

Abstract

雖然富含甘胺酸蛋白質 (GRPs) 在近30年來已被分離鑑定出來，但我們對於其功能還不甚了解。根據先前的研究，已經知道GRPs分佈在細胞中不同位置且具有多樣的功能，以及其相關甘胺酸重複性的序列。阿拉伯芥中的富含甘胺酸蛋白AtGRP11及AtGRP12分別具有6.5%及26.5%的甘胺酸含量。為了近一步了解AtGRP11及AtGRP12的功能，我們對其進行功能及特性之分析。結果顯示，AtGRP11及AtGRP12皆位於細胞壁，而AtGRP11同時也分佈在細胞核中。利用-glucuronidase (GUS) 染色分析，發現AtGRP11會在植物維管束組織中的不同發育階段表現。相較於野生型，AtGRP11基因表現量降低的突變株具有根部較為短小的性狀，而AtGRP12基因的剃除突變株則有根部較長的性狀。此外，AtGRP11及AtGRP12基因皆會受到37℃的高溫誘導表現，而AtGRP11基因也會受到0℃的低溫及鹽逆境誘導表現。再者，分析各突變株的萌芽率及子葉綠化的情形，發現AtGRP11及AtGRP12基因會參與在 abscisic acid (ABA) 及鹽逆境的調控路徑當中，且AtGRP12基因更是參與在先天耐熱性的調控之中。本篇研究說明AtGRP11及AtGRP12基因各編碼著不同的細胞壁蛋白質，且皆會受到不同的非生物逆境誘導表現，可能在細胞壁結構的調控中扮演著重要的角色。

Although glycine rich proteins (GRPs) in plants were isolated nearly 30 years ago, much remains unknown about their function. Previously studied GRPs have been found to have diverse localization and functions, as well as diverse quasi-repetitive glycine repeats. Arabidopsis glycine rich proteins AtGRP11 and AtGRP12 are characterized by 6.5% and 26.5% glycine content, respectively. We have functionally characterized these two proteins to better understand their roles. The results indicated that AtGRP11 and AtGRP12 are localized to the cell wall, and AtGRP11 is also localized to the nucleus. Tissue expression analysis revealed that AtGRP11 is expressed in the vascular tissue at various developmental stages of vegetative plant growth. AtGRP11-knockdown and AtGRP12-knockout mutant plants show shorter and longer root lengths, respectively, as compared to wild-type plants. Both AtGRP11 and AtGRP12 are induced by 37℃ heat, and AtGRP11 is also induced by 0℃ cold and salinity stresses. Moreover, analysis of germination rates and cotyledon greening in mutants indicate that AtGRP11 and AtGRP12 participate in abscisic acid (ABA) and salinity stress responses. Lastly, AtGRP12 was found to play a role in basal thermotolerance. This study shows that AtGRP11 and AtGRP12 are cell wall proteins that are induced by various abiotic stresses, and which possibly serve structural functions.