赤霉素(gibberellins,GAs)信号转导途径相关组分的分离与功能研究对于最终阐明GA作用机制十分重要,目前赤霉素信号途径关键因子DELLA的下游组分研究较少.拟南芥中受GA调控的GASA(GA-Stimulated in Arabidopsis)家族共有15个基因,预测所有GASA蛋白的N端均有一可剪切的信号肽,C端含有12个半胱氨酸的GASA保守结构域.RT-PCR结果证实,在DELLA突变体gai-t6和rga-24以及二者双突变体中,GASA4和GASA6的表达上调而GASA1和GASA9下调,与GASA4和GASA6表达受外源赤霉酸(GA3)促进而GASA1和GASA9表达受GA3抑制的结果相一致.除此之外,其他一些GASA基因表达也分别受GA3和脱落酸(ABA)的独立或共同调控.大部分GASA基因在根、茎、叶、花和幼嫩荚果中均有表达.利用启动子驱动GUS报告基因的方法研究了GASA6,GASA7,GASA8,GASA9,GASA10,GASA11和GASA12等7个基因的器官表达特异性,发现在生长分化旺盛的组织器官及离层区均有这些基因的表达,可能与细胞的分裂和生长有关.本研究为GASA基因家族在GA和ABA信号途径中的功能研究提供重要依据。
PRPs (proline-rich proteins) are a group of cell wall proteins characterized by their proline and hy- droproline-rich repetitive peptides. The expression of PRPs in plants is stimulated by wounding and environmental stress. GASA (gibberellic acid stimulated in Arabidopsis) proteins are small peptides sharing a 60 amino acid conserved C-terminal domain containing twelve invariant cysteine residues. Most of GASAs reported are localized to apoplasm or cell wall and their expression was regulated by gibberellins (GAs). It has been reported that, in French bean, these two proteins encoding by two distinct genes formed a two-component chitin-receptor involved in plant-pathogen interactions when plant was infected. We cloned a full-length cDNA of PRGL (proline-rich GASA-like) gene which encodes a protein containing both PRP and GASA-like domains. It is demonstrated that PRGL is a new protein with characteristics of PRP and GASA by analyzing its protein structure and gene expression.
PENG JianZong, LAI LiuJing & WANG XiaoJing College of Life Sciences, South China Normal University, Guangdong Provincial Key Lab of Biotechnology for Plant Development, Guangzhou 510631, China
