Expression analysis of fungal disease resistant genes in tomato (Solanum lycopersicum L.)

Abstract

Early and late blight diseases caused by Alternaria solani and Phytopthora infestans respectively, adversely affects the tomato production collectively responsible for 49-91% yield loss estimated in Pakistan. Resistance against fungal pathogens is conferred by various resistant R-genes mainly NLR in diverse species. Resistance mechanism of NLR genes is effective method to avoid the fungicide applications and culture practices. In present study, we determined six reported blights resistant genes (NPR1, chitinase, PR1, PAL, Rpi and NRC1) and identified the expression pattern of R-genes in five Solanum lycopersicum accession (38046, 38037, 38039, ROMA and 19890) and one wild specie Solanum Chilense (19906). Structural analysis of these fungal resistant genes was carried out by different Bioinformatics tools. Evolutionary relationship was studied by constructing phylogenetic trees. Expression analysis revealed differential expression pattern of resistant genes in five tomato genotypes and up-regulated in resistant genotype 19890. S. lycopersicum NLR genes containing NBS-LRR domain protein randomly distributed on 12 chromosomes. Conserved motif pattern for NLR genes clustered in one clade and further classified in CNL, NL, N and TN groups within genome. Phylogenetic analysis of resistance genes in tomato with other species showed close relatedness with other members of Solanaceae family. Current findings conclude the screened resistant genotype has expressed strong elevated response against fungal pathogens which proposes the possible involvement of R-genes in defense mechanism and their signaling pathway. It will facilitate the functional validation of resistant genes and developing modern resistant cultivars through gene pyramiding or speed breeding. Keywords: Tomato (Solanum lycopersicum), Alternaria solani, Phytophthora infestans, fungal resistance genes, phylogenetic relationship, Expression pattern analysis