关键词: 番茄, SlN-like, 烟草花叶病毒, 基因表达, 乙烯

Abstract: 【Objective】Solanum lycopersicum is an important vegetable crop, and its growth is persecuted by various biological factors including pests, fungi, bacteria and viruses. Clarifying the antiviral function and mechanism of the S. lycopersicum resistance gene SlN-like provides a theoretical basis for the genetic breeding of antiviral tomatoes and the targeted development of the antiviral agents.【Method】The full length of S. lycopersicum SlN-like was obtained from the Solanaceae Genomics Network database and was divided into 4 segments, fusion PCR was used to amplify it; bioinformatics was used to analysis the evolutionary relationship, protein characteristics, conserved domains, subcellular location and interaction relationship of SlN-like; real-time fluorescent quantitative PCR was used to analysis the SlN-like expression in tomato roots, stems, leaves, flowers and fruits and its response after tobacco mosaic virus (TMV) infection; silencing tomato endogenous SlN-like using tobacco rattle virus (TRV)-mediated gene silencing technology, and the silent plants were inoculated with TMV-GFP to clarify the influence of SlN-like on virus infection. The expressions of abscisic acid (ABA), jasmonic acid (JA) and ethylene (ET) hormone-related genes in silenced plants, and the expression of SlN-like after application of ethephon for 3, 6, 12 and 24 h were analyzed by real-time fluorescence quantitative PCR to investigate the mechanism of tomato SlN-like regulatory hormone pathway in response to virus infection.【Result】Through molecular cloning and fusion PCR technology, a 3 444 bp tomato SlN-like gene was cloned from S. lycopersicum variety Micro-Tom, and uploaded to NCBI to obtain the sequence number MW792493. Through bioinformatics analysis, it was found that SlN-like contains TIR, NB-ARC and NACHT domains, and is closely related to Solanum tuberosum N-like (AAP44394.1). SlN-like expresses in all tissues of tomato, with the highest expression in stems, followed by roots, flowers, leaves and fruits. After TMV-GFP infection tomato at 5 and 7 day, the SlN-like expression was higher than that of PBS treatment, and TMV-GFP infection would cause the expression of SlN-like to increase continuously. TRV vector induced silencing of SlN-like genes in tomato, and found that silencing 87.3% of SlN-like did not affect tomato growth phenotype, but silencing SlN-like promoted the infection of TMV-GFP; real-time fluorescent quantitative PCR analysis found that the expression of ERF1 in SlN-like-silent plants was significantly reduced, only 12.5% of the control group; the expression of SlN-like increased after 3 h of external application of ethephon, and reached the highest peak at 12 h, which was 2.71 times that of the control group, and returned to normal at 24 h. 【Conclusion】S. lycopersicum SlN-like belongs to the NBS-LRR disease-resistant protein family, which contain TIR, NB-ARC and NACHT conserved domains, and expresses in all organs of tomato. The expression of SlN-like is induced by TMV-GFP infection. Silencing SlN-like can promote TMV-GFP infection, revealing that SlN-like acts as a positive regulator to inhibit virus infection. Silencing SlN-like reduced the expression of ET-related gene ERF1, while external application of ethephon resulted in the differential expression of SlN-like, revealing that S. lycopersicum SlN-like participates in tomato antiviral defense through the ethylene pathway.

Key words: Solanum lycopersicum, SlN-like, tobacco mosaic virus, gene expression, ethylene