Abstract：Plant defensins are kinds of small molecular proteins with typical three-dimensional structures, which are composed of cysteine residues, and are also one of important active substances in the process of plant defense. In this study, based on tomato (Solanum lycopersicum) whole genome sequencing data, identification, location, structure, phylogenetic relationship and expression patterns of the tomato defensin gene were performed using bioinformatics methods. Results showed that the tomato genome contained 15 defensin genes, the amino acid sequence length of which was 73~105 aa, while the molecular weight was 8.09 to 11.91 kD. Sequence alignment found that all these members contain Gamma-thionin conservative domain, which was characteristic of defensin genes. Chromosomal location showed that these genes were mapped on 4 chromosomes (Chr 04 Chr 07 Chr 09 and Chr 11). Phylogenetic relationship revealed that the tomato and Arabidopsis thaliana defensin genes could be divided into 7 groups, only one pair was orthologous gene. RNA-Seq analysis found that 6 defensin genes showed tissue-specific expression, expressions of 2 defensin genes were broad spectrum of patterns, and 5 were low in all tissues tested. qRT-PCR results showed that only 2 defensin genes (Solyc07g007750 and Solyc07g007760) were induced by tomato yellow leaf curl virus. All these results suggested that the defensin genes not only involve in the tomato vegetative and reproductive growth, but also may participate in tomato responsing to biotic stresses. This work provides basic data for further function study of the defensin gene family in tomato.
