Genetic multiplex state study of some advanced potato clones conferring Potato virus Y NTN (PVYNTN ) extreme resistance

Abstract

<strong><em>Potato virus </em></strong><strong>Y is known as the most important potato-infecting agent in many parts of the world. In this study, the genetic structure of 16 advanced potato clones that carry the alleles of <em>Ry</em> as an extreme resistance genewereinvestigated. Additionally, multiplex (duplex, triplex or quadruplex) state of genetic of selected clones, where the alleles originate from different species such as <em>Solanum stoloniferum</em> (4X), <em>S. tuberosum</em> subsp. <em>andigena</em> (4X), <em>S. hougassi</em> (6X), were evaluated </strong><strong>using artificial mechanical and graft inoculations under greenhouse conditions. ELISA was used to confirm experimental materials infection.</strong><strong> Results showed that potato clones designated as 96.353, 97.557, 97.559, 97.560, 98.433, 99.373, 99.384, 397097-2, 397082-10, 397074-9, 397081-1 and 396136-1 contain extreme resistance genes (ER) against PVY^NTN.. These selected clones were crossed with a PVY^NTN susceptible line, S440. At least 200 genotypes of each family were evaluated in three replications using mechanical infection with the PVY^NTN.<em> Chi</em> square test was used to prove the fitness of observed segregation ratios in comparison to predicted ones. The results of <em>X</em>² test showed that 99.373, 99.384 and 98.433 clones follow the duplex manner while 96.353, 97.560 and 97.559 were carrying the resistance gene in a simplex state. For 97.557, 397097-2, 397082-10, 397074-9, 397081-1 and 396136-1, there was a significant difference between the observed and expected ratios even for simplex, duplex or triplex stages. The identified duplex genotypes have the potential to provide a durable PVY genetic resistance and can decrease the virus titer in the harboring genotype. </strong>