番木瓜成熟衰老蛋白基因CpSSA的克隆与表达分析

Analysis and Cloning of Fruit Ripening-related Protein Gene CpSSA from Papaya(Carica papaya L.)

衰老相关蛋白(senescence-associated protein,SSA)基因在果实成熟衰老中起重要作用。为了探究番木瓜衰老相关蛋白基因,以‘大白八号’番木瓜果实为材料,采用RACE技术扩增出番木瓜SSA基因全长cDNA序列,命名为CpSSA(登录号:KX885408)。生物信息学分析显示,CpSSA全长1 203 bp,包含一个420 bp的开放性阅读框。番木瓜SSA蛋白含有139个氨基酸,分子质量为15.172 4 kD,等电点为9.61。该蛋白的氨基酸序列与桃、葡萄、杨树、菠菜的氨基酸序列有较高的同源性。系统进化树显示,番木瓜SSA与葡萄SSA表现出最小的进化距离,亲缘关系最接近。用荧光定量PCR分析在不同处理不同成熟度番木瓜果实中CpSSA基因的表达差异,结果显示在乙烯处理后的6 h和12 h表达量显著升高,在1-MCP处理中表达量较低,在乙烯/1-MCP处理果实中的表达模式与成熟衰老有一定相关性,推测CpSSA基因可能参与了番木瓜果实的成熟衰老进程。

Senescence-associated protein（SSA） gene plays an important role in fruit ripening and senescence.Papaya fruits（C.papaya L.cv.＇Daqing No.8＇） were used as material,the full-length cDNA of SSA was isolated by rapid amplification of cDNA ends（RACE） and named as CpSSA（Gen Bank：KX885408）.Bioinformatics analysis indicated that the cDNA of CpSSA is 1 203 bp in length,including a complete open reading frame（ORF） of 420 bp.CpSSA encode a protein of 139 amino acids,with the molecular mass of 15.172 4 kD and an isoelectric point of9.61.The amino acid sequence of the protein had high homology with SSA from peach,grape,poplar,and spinach.Phylogenetic analysis indicated that CpSSA closely related to SSA from grape.Real-time PCR analysis revealed that the expression of CpSSA was significantly increased in 6 h and 12 h in ethylene-treatment and kept a lower expression level in MCP-treatment.Meanwhile,the expression of CpSSA changed as the papaya fruit ripening and senescence,indicating that CpSSA may be involved in the fruit senescence in papaya.