高粱SbSBP17基因的克隆及表达分析

Cloning and Expression Analysis of SbSBP17 in Sorghum

SBP-box(Squamosa promoter Binding Protein box)蛋白是绿色植物中特有的一类转录因子,其功能涉及植物叶片发育、胚胎发生、间隔期长度、营养到生殖生长的更替、育性维持等生长发育的重要过程。该研究以高粱材料BTx623花序总RNA为模板进行RT-PCR,克隆了高粱 SbSBP 17基因,并对其进行了系统进化及半定量PCR表达分析,为进一步研究 SbSBP 17基因的生物学功能奠定基础。结果表明: SbSBP 17含有2个内含子和3个外显子,编码1个444氨基酸的蛋白质,在其195~269 aa区域含有一个典型的SBP-box结构域;系统进化分析表明,18个SBP17蛋白可分为三组,第Ⅰ和Ⅱ组只有单子叶植物基因,而第Ⅲ组只有双子叶植物基因,SbSBP17与玉米PWZ17260.1亲缘关系最近;启动子顺式作用元件分析显示, SbSBP 17启动子含有细胞周期调控元件MSA-like、分生组织发育调控相关元件CAT-box和组织特异性表达元件RY-element等。基因表达分析显示, SbSBP 17是花序特异性表达基因,随着花序发育(长度增加), SbSBP 17基因表达量逐渐增高,当花序长至10 cm时基因表达量达到峰值,约是花序长度最小点(≤2 cm)时的40倍,随后表达量逐渐降低,并于花序长度20 cm时显著降低50%以上。研究推测,随着高粱花序进一步发育, SbSBP 17基因的表达量可能逐渐降低,最终消失。

SBP-box (Squamosa promoter Binding Protein box) genes, belonging to plant-specific transcription factors, involved in many important processes of plant growth, including leaf development, embryogenesis, plastochron formation, vegetative and reproductive phase transitions, et al . SbSBP 17 was amplified by RT-PCR using total RNA extracted from BTx623 inflorescences, phylogenetic analysis and semi-quantitative PCR were performed. This study establishes the foundation for further research of SbSBP 17 functions. SbSBP 17, consist of 2 introns and 3 exons, encoded a protein of 444 amino acids carrying a typical SBP domain(195-269 aa). According to phylogenetic tree analysis, eighteen SBP17 proteins were clustered into three groups (Ⅰ-Ⅲ).Ⅰ and Ⅱ group contained only monocotyledonous proteins, while dicotyledonous protein only existed in group Ⅲ. The orthologous proteins of SbSBP17 was PWZ17260.1 in maize. By analyzing the promoter sequence, several cis-elements were detected, including MSA-like, CAT-box and RY-element, et al . Expression analysis indicated SbSBP 17 was inflorescence-specific gene. With the growth and development of sorghum inflorescence (length increase), the expression level of SbSBP 17 gradually increased and arrived the peak value (40 times than the lowest level) in the 10 cm inflorescence, and then declined significantly by 50% above in 20 cm inflorescence. It was presumed that the expression of SbSBP 17 possibly decreased gradually and ultimately disappeared.