Cloning and expression analysis of SlDFR gene in diseaseresistant tomato varieties Jimei 08

【Objective】To clone the tomato dihydroflavonol 4-reductase(DFR)gene of the resistant varieties Jimei 08 and to analyze its expression in different tissues of tomato induced by Fusarium wilt,so as to provide theoretical reference for exploration of the regulation mechanism of SlDFR gene in the process of tomato disease resistance.【Method】The fulllength cDNA sequence of SlDFR gene from tomato was cloned through homologous cloning technology,and bioinformatics analysis was conducted,and real-time fluorescent quantitative PCR was used to detect the expression pattern of SlDFR gene in tomato roots,stems and leaves induced by Fusarium wilt.【Result】The full-length cDNA of SlDFR was 1659 bp and cDNA contained an open reading frame(ORF)of 1149 bp that encoded 379 amino acids. SIDFR protein had a molecular weight of 42.43 kD and its theoretical isoelectric point(pI)was 6.08,indicating that it was a stable hydrophilic one. And its subcellular localization was on Golgi apparatus without signal peptide and transmembrane domain,with 38 phosphorylation sites,including 18 serine(Ser)phosphate sites,15 threonine(Thr)phosphate sites and 5 tyrosine(Tyr) phosphate sites. In the secondary structure of SlDFR protein,α-helix accounted for 37.73%,extended chain accounted for 13.98%,and random coil accounted for 40.69%. Phylogenetic analysis showed that tomato DFR was closely related to Solanum pennelli followed by Lycium ruthenicum. The results of real-time fluorescence quantitative PCR showed that the expression of SlDFR gene was the highest in leaves,and lowest in roots. After SlDFR gene expression being induced by Fusarium wilt,the expression of SlDFR gene was up-regulated in varying degrees. The change of expression was the largest in roots and the smallest in leaves,indicating that SlDFR gene was related to the stress response of tomato Fusarium wilt,and the synthesis of flavonoids in roots was an important stress response pathway.【Conclusion】After SlDFR gene expression being induced by Fol4287,SlDFR gene could participate in the stress response of tomato Fusarium wilt,and the response to Fusarium wilt is stronger in the root,and probably the gene regulates flavonoid synthesis in the root to enhance antibacterial activity of root exudates,thus increasing the resistance of tomato to Fusarium wilt.