| TYLCD (Tomato yellow leaf curl disease), one of the most important diseases in tomato, has been spreading rapidly worldwide and resulting in heavy losses in China..This disease is caused by several virus sepcies belonging to genus begomovirus of the family Geminiviridae, transmitted by the whitefly, Bemisia tabaci.The most efficient way preventing virus from spreading is breeding resistance cultivars.According to the report,it indicate that no source of resistance to begomoviruses have been identified in S. lycopersicum since then. Source of resistance to TYLCV have been discovered in wild tomato species,including S.pimpinellifolium,S.peruvianum, S.habrochaites,S.chilense,S.cheesmanii.Thus,breedi-ng for TYLCV resistance has been largely based on the transfer of resistance genes from the wild accessions into the cultivated tomato.In order to speed up the breeding progress in marker-assisted selection and prevent this disease from spreading,In the current study, breeding line CLN2777A that display a high level of resistance to TYLCV and TMXA48-4-0 that display susceptible to TYLCV and F2 progeny derived from cross of two parents were used to screen the markes linked to resistance gene to TYLCV by AFLP and SSR with BSA. Another section is about the research of pyramiding resistant genes in marker-assisted selection with three markers,which developed by the breeders of overseas,linked to Ty-1,Ty-2,Ty-3, respectively.The result is follow:1.Through the inoculation of the parents and F2 progeny with TYLCV by whiteflies, it proves that segregation ratio of symptom conform with the expected segregation of 3:1 and the resistance to TYLCV is controlled by a single dominant gene. With 512 MseⅠ/PstⅠprimer combination, AFLP analysis was performed on parents and resistant and susceptible bulks. The final results is that the primer combination P15M28 and P16M10 show the association to resistant gene, the fragment sequencing of the AFLP marker indicated the length was 106bp,180bp and dignated P15M28-106, P16M10-180,respectively,and P15M28-106 converted to a CAPS marker successfully.Through the identification of F2 progeny, genetic distance is 8.8cM and named P15M28, it concluded that the marker P15M28 adapt to apply in marker-assistant selection breeding.In the additional,? SSR markers between TG36 and TG393 in the 11 chromosome of the tomato linkage map constructed by Kenta Shirasawa were screened with the same F2 progeny.it proved that EST-SSR marker TES0344 was related to resistance gene.through the genetic analysis, the genetic distance is 7.8 cM.2.TY52,CLN2777A,99S-C-39-20-1-1-24-17-0-0, three accessions which show resistance to TYLCV and include Ty-1,Ty-2,Ty-3,respectively,and three susceptible accessions Tmm9060-0, TMXA48-4-0, TA1218 were used in the research on the resistance pyramiding by MAS.According to the program, cross of these accessions were made and plants of every progeny were analysised in MAS.The result is that three different homozygous lines with two resistance genes were cultivated by MAS strategy and inoculation test by whitefly showed these lines have high resistance to TYLCV. |
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