高粱AGO蛋白家族基因鉴定及表达分析

Argonaute (AGO)蛋白是RNA介导的沉默复合物RISC的核心成分,在小RNA、Dicer?like酶等的协同下共同激发RNA沉默反应。为阐明高粱中AGO蛋白的功能,本研究采用生物信息学的方法首次在高粱全基因组水平鉴定15个SbAGOs,分别定位于高粱的7条染色体上,根据氨基酸序列将其划分为三个亚家族。亚家族Ⅲ中SbAGO7和SbAGO3都含有3个外显子,亚家族Ⅱ中SbAGO4和SbAGO6都具有22个外显子,成员最多的亚家族Ⅰ中基因外显子数量介于19~24之间。其中,亚家族Ⅰ中SbAGO1-1和SbAGO1-3、SbAGO1-3和SbAGO1-4、SbAGO5-2和SbAGO5-4发生过基因复制事件,可能存在功能冗余现象。NCBI表达谱数据库分析发现,SbAGO1-1、SbAGO1-2、SbAGO1-3和SbAGO4在高粱不同组织器官和生长发育阶段均有较高表达,其中SbAGO1-1和SbAGO1-2、SbAGO1-3和SbAGO4表达时期和表达量基本一致,可能在调控高粱生长发育方面发挥协同作用。高温、干旱及高温与干旱复合逆境表达谱芯片数据分析发现,高温处理引起5个SbAGOs基因差异表达,干旱处理SbAGOs表达变化不明显,复合逆境引起7个SbAGOs基因差异表达;2个处理共同差异表达基因为SbAGO1-3、SbAGO1-1、SbAGO5-2和SbAGO3,表达量变化趋势相近。其中SbAGO1-1、SbAGO1-2、SbAGO1-3和SbAGO5-6下调表达,SbAGO3、SbAGO5-2、SbAGO1-4和SbAGO10上调表达。本研究结果为揭示SbAGO蛋白功能和发掘高粱的抗逆育种靶向基因资源提供了一定的理论依据。

Identification and Expression Analysis of AGO Protein Family Genes in Sorghum bicolor

Argonaute (AGO) proteins are the core element of RNA?induced silencing complex(RISC)which could stimulate RNA silencing reaction with the cooperation of sRNA and Dicer?like protein. In order to fully understand the function of AGO proteins in sorghum (Sorghum bicolor (L.) Moench), this study used bioinformatics method to identify 15 SbAGOs at whole genome level of sorghum for the first time, which were located on seven chromosomes of sorghum and divided into three subfamilies according to the amino acid sequence. Among which, SbAGO7 and SbAGO3 belonging subfamilyⅢ had 3 exons and SbAGO4 and SbAGO6 in subfamily Ⅱ had 22 exons. The largest subfamily 19-24 extrons. Among them, genetic replication had occurred on SbAGO1-1 and SbAGO1-3, SbAGO1-3 and SbAGO1-4, SbAGO5-2 and SbAGO5-4 in subfamily Ⅰ, indicated there were functional redundancy. Through NCBI expression profiling database analysis, SbAGO1-1, SbAGO1-2, SbAGO1-3 and SbAGO4 were highly expressed in different tissues and organs and in different growth stage. Also, the expression period and the expression level of SbAGO1-1 and SbAGO1-2, SbAGO1-3 and SbAGO4 were similar. They may play a synergistic role in regulating the growth of sorghum. Through the data analysis of Chipgene expression profile under high temperature, drought and high temperature combine with drought stress, it was found that high temperature induced differential expression of five SbAGOs genes, and the changes of SbAGOs expression under drought stress was not obvious. Under combined stress, 7 SbAGO genes were differentially expressed; The common differentially expressed genes were SbAGO1-3,SbAGO1-1, SbAGO5-2 and SbAGO3 after two treatments and their expression changes were similar. SbAGO1-1, SbAGO1-2, SbAGO1-3 and SbAGO5-6 were down?regulated while SbAGO3, SbAGO5-2, SbAGO1-4 and SbAGO10 were up?regulated. The results of this study provide a theoretical basis for revealing and exploring the function of SbAGO proteins and the targeted genetic resources of sorghum resistance breeding.