MAPPING OF THE GENE NX(PHU) THAT CONTROLS HYPERSENSITIVE RESISTANCE TO POTATO-VIRUS X IN SOLANUM-PHUREJA LVP35

The line IvP35 of the diploid (2n = 2x = 24) cultivated potato species Solanum phureja (family Solanaceae) expresses hypersensitive resistan ce (H) to potato X potexvirus (PVX). In this study, a diploid potato p opulation was produced using IvP35 as the male parent and a diploid li ne of S. tuberosum (87HW13.7) as the female parent and tested for resi stance to PVX. Data indicated that H to PVX in IvP35 is a dominant, mo nogenically inherited trait controlled by a single gene, named Nx(phu) , that is in a simplex condition (Nxnx). RFLP analysis carried out on the progeny lines revealed 4 markers (CT220, TG328, CT112 and TG424) f rom the long arm of chromosome IX that were linked to the hypersensiti ve phenotype; the closest linkage was observed with the marker TG424. Previous authors have shown that the same region of chromosome IX cont ains the gene Sw-5 for resistance to tomato spotted wilt tospovirus in Lycopersicon peruvianum (Solanaceae).