Location: Plant Germplasm Introduction and Testing
Title: Rapid pyramiding major resistance genes into parental lines in tomato hybrid breeding employing marker-assisted backcrossing Author
Submitted to: International Conference on Solanaceae Resistance Breeding
Publication Type: Abstract Only
Publication Acceptance Date: January 15, 2011
Publication Date: February 17, 2011
Citation: Hu, J. 2011. Rapid pyramiding major resistance genes into parental lines in tomato hybrid breeding employing marker-assisted backcrossing. International Conference on Solanaceae Resistance Breeding. P 20. Technical Abstract: The success of marker-assisted pyramiding major resistance genes depends upon several factors, including the closeness between the markers and the target gene, the number of target genes to be pyramided, the kind of molecular markers to be used, and available technical facilities. This talk will discuss an efficient scheme of deploying DNA marker technology in marker-assisted backcrossing to pyramid major resistance genes into parental lines for producing commercial tomato hybrid varieties. The process starts with identifying elite parental lines as recipients and donor germplasm with the target gene and associated marker information. DNA markers are used from BC1F1 to BC6F1 generations to identify heterozygotes with the target gene to be used in continued backcross. A pathogen inoculation test is needed at BC4F1 to ensure that the target gene is functioning in the new genetic background and that the marker is not segregated away from the target gene when they are not tightly linked. Small pots (4-inch in diameter) are used for rapid generation advance with a seed-to-seed time with 90 days or less. In this way, seven generations can be completed within two years during which a few target genes can be incorporated into recipient parental lines to produce improved hybrid varieties. At the completion of the backcrossing, a second round of pathogen inoculation test is carried out for the BC7F2 population to identify resistance progenies followed by DNA marker screen to eliminate heterozygotes. The resulting homozygote plants are new improved parental lines for making experimental hybrids for field trials. The advent of new technology and the rapid growth of genome sequence data will open a new world of genotyping and selection applications As a supplement to traditional breeding, marker-assisted selection will play an important role in crop improvement during the coming years.