Isolation of Two Genes Encoding Nonspecific Lipid Transfer Protein and Their Expression Profiles in Ipomoea batatas(英文稿)

Nonspecific lipid transfer proteins (nsLTPs) are widely distributed in the plant kingdom and are involved in various stress responses. To clarify the function of nsLTP genes, IbLTP1 and IbLTP2 were cloned by PCR technology, and the sequence structures, conserved domains, and evolutionary relationships were analyzed.Sequences of cDNAs and genomic genes showed that neither gene had introns, but both had several homologous isoforms. IbLTP1 and IbLTP2 encode proteins of 114 and 94 amino acid residues respectively, without any Trp. These proteins contain a signal peptide at the N-terminal and have conserved domains of nsLTP1 and nsLTP2, respectively. The expression patterns and expression differences of IbLTP1 and IbLTP2 in different tissues and under stress were determined by real-time RT-PCR. Results showed that IbLTP1 and IbLTP2 had higher relative expression levels in young leaves and stems, respectively, and were highly induced under sodium chloride (NaCl) stress. The coding sequences of IbLTP1 and IbLTP2 were cloned into expression vector pET32a and expressed in Escherichia coli BL21 (DE3), respectively. The maximal OD₆₀₀ values of strains harboring pET32a-IbLTP1 and pET32a-IbLTP2 were higher than those of the pET32a transformed strain under NaCl stress.