Zróżnicowanie reakcji odpornościowej na wirus Y ziemniaka wśród alloplazmatycznych form tytoniu

Abstract

Cytoplasmic male sterility is used in plant breeding to obtainforms incapable of self-pollination, which are utilized mainlyin breeding of hybrid cultivars. It is based on incompatibilitybetween the cell nucleus and cytoplasm because cytoplasmicmale sterile plants are obtained by mutation in the cytoplasmicgenome or by substitution of the native cytoplasm with anotherthat of a different species. Alloplasmic forms develop modified,non-functional male generative organs or do not develop themat all. Morphological changes may involve other parts of flowersand sometimes a whole plant. An alien cytoplasm may alsoaffect other traits, including resistance to pathogens. In order todetermine the effect of alien cytoplasm on tobacco resistance toPotato virus Y (PVY), artificial inoculations with two virus isolatesdiffering in virulence were performed. The test included13 alloplasmic forms of cultivar Zamojska 4 with cytoplasmfrom Nicotiana wild species and a form with cytoplasm fromthe mutant obtained within Nicotiana tabacum. Plant resistancewas assessed on the basis of disease symptoms and DAS-ELISAimmunoenzymatic test results. Differences were observed inthe severity and earliness of disease symptoms. Fertile cultivarZamojska 4 is considered as tolerant to PVY, that is it reacts toinfection with mild symptoms like vein clearing and chloroticspots of the leaves, but not with vein necrosis. In the case ofa combination of cell nucleus from cv. Zamojska 4 and cytoplasmfrom species N. goodspeedii, N. megalosiphon and N.undulata, alloplasmic forms were not completely resistant, butthe level of their tolerance to strong isolate IUNG20 increasedcompared to that in their male fertile isogenomic counterpartand observed symptoms were delayed. In contrast, tolerance ofcms forms with cytoplasm from the species N. eastii, N. occidentalisand N. suaveolens was overcome leading to developingsevere disease symptoms. Unlike the other cms forms, theform with the cytoplasm of N. tabacum mutant reacted witha development of necrotic symptoms to inoculation with isolateIUNG20, but with delayed mild symptoms when inoculatedwith the weaker isolate IUNG21. The diversified reaction ofdifferent isogenomic alloplasmic forms to viral infection suggeststhat the mechanisms of defense responses depended onthe type of cytoplasm.