Molecular marker-assisted selection for pyramiding resistance genes in tomato.

摘要

The use of molecular markers linked to resistance genes can highly improve the breeding schemes aimed to both deploying and pyramiding resistance genes. The aim of this study was to confirm that the molecular marker technology could be easily integrated into breeding programmes to transfer and combine resistance to various pathogens into superior tomato lines. To pyramid several resistance genes in the same variety, 2 near-isogenic lines, each possessing at least 3 resistant genes (Momor, which was resistant to TMV [tobacco mosaic virus], Verticillium dahliae and Fusarium oxysporum f.sp. radicis-lycopersici, and Motelle, which was resistant to V. dahliae, F. oxysporum f.sp. lycopersici, Stemphylium sp. and Meloidogyne incognita), were intercrossed and selfed for many generations. Selection for resistance was performed using molecular markers linked to the genes to fix them at the homozygous level in the same genotype. These were mainly CAPS markers, which are easy to be detected by simple laboratory analyses. After the F4 generation, it was possible to obtain various genotypes which carried all resistance genes at homozygous condition. This objective was achieved through the early molecular screening for resistance, a very efficient tool in reducing time and space necessary for selection..