Great expansion of the Mi-1 gene cluster in Solanum tuberosum

SEGURA, DIANA, SANCHEZ PUERTA, M. VIRGINIA, MASUELLI, RICARDO W.

Potrero de los Funes

Congreso; SAIB; 2011

Root-knot nematodes are able to attack and seriously damage all the major crops. Resistance to the nematode Meloidogyne incognita has been introduced in tomato, Solanum lycopersicum, and consists in a multigene locus called Mi-1. Homologs to the gene Mi-1 in the genus Solanum have been reported from three potato species, S. bulbocastanum, S. phureja and S. tuberosum. The aim of this work is to study evolutionary relationships among Mi-1 homologs in the genus Solanum. We amplified, cloned and sequenced 13 homologs from the wild potato S. kurtzianum, which showed tolerance to M. incognita infection. Also, we analyzed more than 120 Mi-1 homologs from S. tuberosum, obtained from Genbank databases using BLAST. These homologs were aligned and edited manually using MacClade. Maximum likelihood analyses were performed with Garli. The phylogenetic tree showed a great expansion of the homologous Mi-1 locus in S. tuberosum with two main gene clusters located in chromosomes 5 and 6. Sequences from S. kurtzianum grouped with S. tuberosum Mi-1 homologs from chromosome 6. We also observed at least seven translocations to other chromosomes (chr 1, 8, 9 and 11) in the genome of S. tuberosum. Putative repetitive hybridizations in the origin of the cultivated potato may be responsible for the multiple duplication events of Mi-1 homologs.