ASSESSMENT OF THE INFECTION RESISTANCE LEVEL FROM TWO DIFFERENT POTATO (Solanum tuberosum ssp. Tuberosum) CROPS TO THE VIRUSES PVX, PVY AND PLRV

There are approximately 40 viruses and two viroids that are capable of naturally infect potato crops. The virus PLRV is considered the most important and harmful one worldwide, can generate up to 80% yield reductions. PVY and PVX, found all around the world, can also lead to important yield reductions and present synergic effects between each other. The current study evaluated the resistance level in two potato cultivars, “Unica” and “393-085.5”, to the presence of the viruses PVX, PVY and PLRV in an altitudinal gradient located at 2432 meters above sea level in the province of Cartago, Costa Rica. The experimental parcel was planted using the randomized complete block design in order to evaluate through molecular techniques (RT-PCR multiplex using PVXf, PVXr, PVYf, PVYr, PLRVf and PLRVr primers) and ultrastructural techniques (through TEM), the level of infection presented in the “Unica” and “393-085.5” cultivars. Through Cochran’s ANOVA Q it was determined that the evaluated cultivars presented different effect levels for each of the studied viruses. It was concluded that the analyzed viruses led to considerable affectations to the primary metabolism of the assessed plants, since they had a direct effect on the chloroplasts, which swelled and the mitochondrial crests dilated. It was also possible to observe a proliferation in the membranes of the endoplasmic reticulum and the dictyosome. In regards to the yields obtained from the growth of the “Unica” and “395-085.5” cultivars, it was determined that there is not a direct influence of the studied viruses related to the production of potato tuber.