Genome-Wide Analysis Of NBS-LRR Resistance Genes And Insilico Identification And Expression Analysis Of Candidate Genes Related To TY-2 Resistance Gene In Tomato

Tomato(Solanum Lycopersicum Mill.), belongs to the Solanaceae. It’s the second-largest vegetable crops in the world just after potato, but the production of tomato always severely constrained by the pathogens. NBS-LRR (Nucleotide Binding Site-Leucine Rich Repeat) is one of the largest gene families in plant genome. Tomato yellow leaf curl virus disease (TYLCVD) is one of the main diseases effect tomato production in the world, while, Ty-2 is one of the major resistance genes response to TYLCVD, especially in Asian regions. Ty-2 are found between the molecular markers C2_At2g28250 (82.3 cM) and T0302 (89.0 cM). In order to analyze tomato NBS-LRR gene family, the number of tomato NBS-LRR genes was identified by bioinformatics method based on tomato genome database. Further, the chromosome distribution and phylogenetic relationship analysis of tomato NBS-LRR genes were performed. Subsequently, comparison analysis of tomato and potato NBS-LRR resistance genes was performed. For narrowing the identification range of Ty-2 gene, and provide a basic of molecular markers development for Ty-2 fine positioning and reveal its founctions, we analyzed genes in the region of Ty-2 gene using bioinformatics methods based on tomato genome information. The result reveald these candidate genes not only involved in tomato growth development, but also participated in the responses to variety diseases. Results as follows:1 Genome-wide analysis of NBS-LRR resistance genes in tomatoThe result showed a total of 252 NBS-LRR resistance genes were identified. These genes located widely on 12 chromosomes. Approximate 63.5% NBS-LRR resistance genes appeared in clusters and most of them were in tandem duplication. Microsynteny analysis revealed that 79 NBS-LRR resistance genes from tomato have high homology with those from potato. The results will provide a basis for studying deeply NBS-LRR resistance genes in tomato, and give a platform for mapping and cloning of resistance genes in future.2 In silico identification and expression analysis of candidate genes related to Ty-2 resistance gene in tomatoThe results demonstrated that there were 69 encoded genes between the molecular markers C2_At2g28250 and T0302 in the physical interval, of which there were 22 disease-related resistant genes including NBS-LRR disease resistance gene, protease genes (protein kinase, kinase receptor, protein isomerase and so on), cytochrome and transcription factors. EST-based expression analysis revealed that there were 77.3%(17/22) candidate disease resistance genes with expression characteristics,143 ESTs involved; Based on the full length cDNA sequence analysis, there were 7 candidates with expression-specific characteristics, of which 4 candidate genes were involved in stress responses of plants to pathogens; Microarray-based expression analysis showed that most candidate genes were involved in tomato responses to pathogens such as fungi, viruses and bacteria. RNA-Seq based expression analysis revealed that all the candidate genes participated in the growth and development of tomato. In short, disease-resistant candidate genes of Ty-2 are restricted to the range of 22 genes by the bioinformatics methods, and expression analysis confirm that they are involved in growth and development of tomato, and stress responses to adversity, which will provided a foundation for the further development of molecular markers for fine mapping and function analysis.