关键词: 番茄, COBRA基因, 克隆, 表达模式, 生物信息学分析

Abstract: COBRA is a member of plant-specific glycosylphosphatidylinositol (GPI)-anchored protein family and plays an important role in controlling cellulose content of cell wall and orientation of cell expansion. Although studies on COBRA mutants from Arabidopsis, Oryza sativa and Zea mays have been extensively performed, the function of ortholog of COBRA in tomato remains largely unknown. In this study, a full-length cDNA sequence highly homologous with other plant COBRA genes was identified by RT-PCR from tomato seeding, and named as SlCOBRA(GenBank Accession No.JN398667). Results of sequence analyses showed that SlCOBRA is composed of six exons encoding a 444-amino acid protein, containing conserved features of the COBRA protein, such as a CCVS motif, an N-terminal signal peptide sequence for secretion, a highly hydrophobic C terminus, and specific features around the ω-site required for processing. Phylogenetic analysis revealed that the deduced amino acid sequence of SlCOBRA shows 80% identity with that of Arabidopsis AtCOB, thereby being organized in the same clade. Meanwhile, the expression pattern of tomato COBRA was revealed by real-time PCR. The results showed that tomato COBRA exhibits higher expression levels in roots, shoots, flower and fruits, but only during the green stages of tomato fruit development, prior to visible signs of ripening. At the start of the breaker stage, the levels of tomato COBRA mRNA decline dramatically.

Key words: Tomato, COBRA genes, Cloning, Expression pattern, Bioinformation analysis