Molecular Markers For Resistance Gene Ty-1 And Their Utilization In Marker-assisted Selection

Tomato yellow leaf curl disease (TYLCD) is a devastating disease, which occurred in tomato production in recent years. Ty-1 was the first discovered resistance gene for tomato yellow leaf curl virus. In this study, resistant heterozygous (Ty-1/ty-1) , resistant homozygotes (Ty-1/Ty-1) and susceptible homozygotes (ty-1/ty-1) are used as experimental materials. The primers are based on the published RFLP markers which are tightly linked to Ty-1, and the restriction enzyme analysis was based on the PCR amplification fragments. The study gained TG97 CAPS marker and Mi23 CAPS marker, which are tightly linked to resistance gene Ty-1. The two resistance markers can distinguish heterozygous and homozygous, and they are co-dominant CAPS markers.(1) TG97 CAPS marker: by PCR amplification and enzymes digested, resistant homozygous materials appear 398 bp, 303 bp and 95 bp specific segment; resistant homozygous materials appear 303 bp and 95 bp specific segment; And susceptible homozygote materials appears only 398 bp segment. Primer sequences are TG97 F(5'-TAA TCC GTC GTT ACC TCT CCT T-3')and TG97 R (5'-CGG ATG ACT TCA ATA GCA ATG A-3'). The restriction enzyme used in the experiment is Taq I. (2) Mi23 CAPS marker;by PCR amplification and enzymes digested, resistant homozygous materials get 402 bp and 354 bp specific segment; resistant homozygous materials get 402 bp specific segment; And susceptible homozygote materials get 354 bp segment. Primer sequences are Mi23 F(5 ' -TGG AAA AAT GTT GAA TTT CTT TTG-3 '), Mi23 R (5'-GCA TAC TAT ATG GCT TGT TTA CCC-3'). The restriction enzyme used in the experiment is Rsal.With the experimental materials of different sources and different genetic background, effectiveness of TG97 CAPS marker and Mi23 CAPS marker were proved. Electrophoresis results verify that the CAPS markers TG97 and Mi23 are stability and effectiveness, and TG97 CAPS markers were more clearly and easily recognizable, which is an ideal markers and can be utilized in the marker-assisted selection.In the F2 populations of tomato seedling, TG97 CAPS marker and Mi23 CAPS marker were used in the assisted selection, and get resistant homozygous genotypes: 15, 20, 32, 33, 35, 36, 41, 43, 49, 58. These ten were grown in the field and self seed. The F3 lines obtained three good lines, which are 33-1, 35-1, 43-1. 33-1 is the unlimited growth type, red fruits, its fruit weight 160g-180g, high output. 35-1 is the unlimited growth type, red fruits, fruit weight 130g-150g, hardness. 43-1 is unlimited growth type, red fruits, fruit weight 110g-120g, hard, good commodity.TG97 CAPS marker and Mi23 CAPS marker, which are tightly linked to resistance gene Ty-1, lay a foundation for resistance breeding materials selection, identification and Marker-assisted selection. The three lines are low incidence for TYLCV, and their biological characteristics are better. after further breeding, the three lines can be used in breeding for disease resistance.