Polymorphism of the KPI-A gene sequence in the potato subgenera Potatoe (sect. Petota, Estolonifera, and Lyconpersicum) and Solanum

Group A Kunitz-type protease inhibitors (KPIA) are involved in protecting potato plants from microorganisms and pests. While the nucleotide sequence is known for many KPIA genes of various potato cultivars (Solanum tuberosum subsp. tuberosum) and a few genes of tomato (Solanum lycopersicum), there are no data on their allelic diversity in other species of the genus Solanum. KPIA fragments were cloned, amplified, sequenced, and analyzed from plants of the subgenera Potatoe sect. Petota (five genes from S. tuberosum ssp. andigenum and two genes from S. stoloniferum) and Solanum (five genes from S. nugrum), and their con sensus sequences were established. An identity of 97-100% was observed among these sequences and the KPIA sequences of the sections Petota (cultivated potato Solanum tuberosum ssp. tuberosum) and Etuberosum (S. palustre) The interspecific variation of KPIA did not exceed its intraspecific variation for all but one species (S. lycopersicum). The distribution of highly variable and conserved sequences in the mature protein coding region was the same in all of the above species. The same primers failed to amplify the homologous genes from Solanum dulcamara, S. lycopersicum, and Mandragora officinarum. Phylogenetic analysis of the KPIA sequences showed that S. lycopersicum clustered separately from all of the other species examined, that S. nigrum clustered together with species of the sections Etuberosum and Petota, and that these species produced no speciesspecific clusters. Although S. nigrum is resistant to all known races of the oomycete Phytophthora infestans, which causes one of the most economically important diseases of Solanaceae, the aminoacid sequences encoded by S. nigrum KPIA differed slightly, if at all, from their counterparts of cultivated potato, which is susceptible to P. infestans infection.