PLPKI as a potential biochemical marker involved in horizontal resistance to Phytophthora infestans in potatoes

FELDMAN ML; KORGAN S.; HUARTE MA; DALEO G.R.; ANDREU A.B.

Puerto Madryn

Congreso; XLVI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular. SAIB; 2010

Sociedad Argentina de Investigaciones Bioquímicas y Moleculares

Late Blight (LB) is the main disease that affects potatoes around the world. Due to the unavailability of effective chemical control methods and the intensive use of fungicides, the introduction of genetic resistance to LB represents a safe strategy. Two forms of genetic resistance to Phytophthora infestans (Pi) in potato species have been described, vertical resistance (VR) or horizontal resistance (HR). VR is characterized by interactions between products of dominant R genes in the host and corresponding avirulence genes in the pathogen. In contrast, HR, is assumed to be multiple gene-based. This type of resistance is durable and thus commercially more attractive than VR. In our lab, we have isolated and characterized a potato serine proteinase inhibitor specific for proteinase K (PLPKI) and which was only induced in leaves of a potato cultivar with a high degree of HR upon infection with Pi. The aim of the present work was to establish a correlation between the degrees of HR with the accumulation of PLPKI in Solanum tarijense species (tjr), which are part of the Argentinean Potato Breeding Program. Western blot analysis with an specific antibody raised against PLPKI showed a positive correlation when we evaluated clones tjr with different degree of HR, showing the highest accumulation of PLPKI in clone OKA 5632.11 which has been described as high resistant. Proteinase K inhibitor activity was also correlated with the degree of HR. These results suggest that PLPKI can be potentially used as a biochemical marker to assist breeders in the selection of HR cultivars.