Identification of Late Blight Resistance Gene Homologues in Wild Solanum Species

Solanum wild species represent diverse population harbouring myriad of resistance (R) genes which could be tapped for incorporating durable biotic and abiotic stress resistance in cultivated genotypes. In the present study, the authors report the screening of eleven Solanum wild species viz., Solanum avilesii, S. berthaultii, S. tuberosum sp andigena, S. arnezii, S. cardiophyllum, S. alandiae, S. albicans, S. sparsipilum, S. spegazzinii, S. pinnatisectum and S. demissum for the presence of late blight resistance genes through molecular markers linked to genes RB/Rpi-blb1, Rpi-ber1, R1 and R3. These markers were able to amplify specific sequences across species indicating universal distribution of R genes. The amplified marker specific sequences matched well with sequences in NCBI database with known function in governing late blight resistance. Phylogenetic analysis grouped the sequences to their known counterpart’s. e.g. sequences amplified with Rpi-blb1 gene specific marker grouped with known sequence corresponding to Solanum bulbocastanum protein genes and so forth in other sequence-marker combinations. The presence of such genes was not immediately linked to resistance against late blight in the wild species accession but may have a role in maintaining/developing their resistance against novel pathogenic races. The newly identified R gene homologues (fragments) in the highly resistant wild potato accessions can serve as a novel source of genes for late blight resistance breeding. The complementary late blight resistant genes from different species can be pyramided in cultivated genotypes for providing stable late blight resistance. © 2016, The National Academy of Sciences, India.