GENETICS OF TOMATO SPOTTED WILT VIRUS-RESISTANCE COMING FROM LYCOPERSICON-PERUVIANUM

New resistance sources coming from Lycopersicon peruvianum, especially those introgressed in UPV 32 line, are studied. UPV 32 resistance is controlled by a single gene. Resistance and dominance levels of this g ene are conditioned by thrips transmission and isolate aggressiveness, A partial overcoming of resistance occurs due to the incomplete penet rance of the gene. Incomplete dominance of resistance also happens, wh ich suggests gene dosage dependence. UPV 32 gene segregates independen tly of both Sw-5 gene and UPV 1 resistance gene, also coming from Lyco persicon peruvianum. It is proposed to name Sw-6 this new locus from U PV 32. Sw-5 gene and UPV 1 resistance gene show higher resistance than Sw-6. Heterozygotes for UPV 1 resistance gene were more resistant tha n heterozygotes for Sw-5. The lower dependence of UPV 1 resistance gen e on the gene dosage effect makes it very useful for the development o f commercial hybrids.