Molecular Markers For Resistance Gene Ty-2and Their Utilization In Marker-assisted Selection

Tomato yellow leaf curl disease (TYLCD) is a devastating disease occurring ontomato production in recent years. Ty-2is one of the effective resistance genes for tomatoyellow leaf curl virus. In this study, resistant heterozygous (Ty-2/ty-2), resistanthomozygotes (Ty-2/Ty-2) and susceptible homozygotes (ty-2/ty-2) were used asexperimental materials. The primers were designed based on the published RFLP markerswhich are tightly linked to Ty-2. Two co-dominant SCAR molecular markers for Ty-2,T0302-1and T0302-2, were acquired by the techonology of SCAR and CAPS. The twomarkers as co-dominant SCAR markers can distinguish heterozygous and homozygous.(1) The SCAR marker T0302-1: The marker T0302-1gave a fragment of800bp forthe susceptible homozygotes, a fragment of900bp for resistant homozygous and both thefragments of800bp and900bp for resistant heterozygotes materials. The primers’sequences are T0302F:5’-TGG CTC ATC CTG AAG CTG ATA GCGC-3’; T0302R:5’-AGT GTA CAT CCT TGC CAT TGACT-3’.(2) The SCAR marker T0302-2: The marker T0302-2gave a fragment of450bp forthe susceptible homozygotes, a fragment of600bp for resistant homozygous and both thefragments of450bp and600bp for resistant heterozygotes materials. The primers’sequences are T0302F:5’-TGG CTC ATC CTG AAG CTG ATA GCGC-3’; TY2R1:5’-TGA T(T/G)T GAT GTT CTC (T/A)TC TCT (C/A)GC CTG-3’. 11kinds of tomato materials from different sources and with different geneticbackground were used to prove the effectiveness of the two markers. The results verifiedthat the two SCAR markers, T0302-1and T0302-2, were steady and effective. Meanwhile,compared comprehensively, marker T0302-2was more clearly and easily recognized whenused in distinguishing heterozygotes materials. It is an ideal marker and can be utilized inthe marker-assisted selection for TYLCD resistant breeding of tomato.Co-dominant SCAR markers T0302-2was used to distinguish the gene types of theF2populations of tomato seedlings and24resistant homozygous were got. These24seedlings were planted in the field. Finally, seven of them performered preferableeconomic characters and were picked after a biology characters’ surveying.Co-dominant SCAR markers T0302-1and T0302-2, which are tightly linked toresistance gene Ty-2, lay a foundation for the identification and marker-assisted selectionof resistance breeding materials. After further breeding，the7plants with preferablecharacters can be used in breeding for disease resistance.