ISHS Acta Horticulturae 695: I International Symposium on Tomato Diseases
SEARCHING FOR SILVERLEAF WHITEFLY AND BEGOMOVIRUS RESISTANCE GENES FROM LYCOPERSICON HIRSUTUM ACCESSION LA1777 |
| Authors: | A. Momotaz, J.W. Scott, D.J. Schuster |
| Keywords: | Bemisia argentifolii, insect resistance, RFLP marker, trichome, recombinant inbred lines, tomato, Lycopersicon esculentum, tomato yellow leaf curl virus (TYLCV), tomato mottle virus (ToMoV) |
| Abstract:
Ninety-four recombinant inbred lines (RILs) developed from LA1777 that span 85% of the L. hirsutum genome, resistant parent (LA1777), susceptible parent (E6203), and three interspecific F1 hybrids were tested for whitefly resistance using clip cages and assayed for trichome type and density in a greenhouse. No adults settled on leaflets of LA1777, which had many type IV trichomes while E6203 had none. Most of the RILs had as many eggs deposited on their leaflets as E6203 and none had type IV trichomes, likely indicating that control of type IV trichome production and the associated factors conferring whitefly mortality is multigenic. Alternatively, type IV trichomes and insect mortality may be controlled by the genes in 15% of the genome not represented by the tested RIL population. The F1 plants had no adult mortality, but all had a lower number of deposited eggs than E6203 and the RILs. The F1s also had intermediate phenotypes with dense trichomes; mostly type VI’s with few type IV’s. This indicates reduced insect resistance in heterozygotes. These 89 RILs were screened against the begomoviruses tomato mottle virus (ToMoV) and tomato yellow leaf curl virus (TYLCV). Thirteen lines showed a low level of tolerance to TYLCV and/or ToMoV. Eight of these lines had L. hirsutum alleles at TG27 (RFLP marker) on chromosome 1, three of the lines had L. hirsutum alleles at TG202 on chromosome 7 and one RIL had L. hirsutum alleles at both marker loci. The RIL that had both TG27 and TG202 markers did not show an increased level of TYLCV tolerance, and appeared susceptible to ToMoV. These findings suggest genes on chromosomes 1 and 7, from LA1777 have only a minor effect on begomovirus tolerance. | |
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