STRATEGIES FOR BREEDING IN ACTINIDIA (KIWIFRUIT): A FRAMEWORK MAP AND ITS USES

Breeding in Actinidia is complicated by dioecy, polyploidy, and a long juvenile period. While the fruit characters of the female plants are seen at sexual maturity, the contribution which the male parent makes in relation to fruit quality is unknown, and assumed through studying sister sibs, or carrying out time-consuming and expensive progeny testing. A framework map to determine linkage groups is being constructed using about 200 microsatellite markers. Microsatellites are plentiful in the genome, co-dominant, randomly distributed, and offer ease of handling and reproducibility. Their disadvantage is cost and difficulty of isolation. We used microsatellites from enriched genomic libraries, cDNA libraries and isolated sequences, to identify microsatellites which were polymorphic in a wide intraspecific mapping cross in the diploid species Actinidia chinensis. Primers were designed to sequence information surrounding each microsatellite, labelled with fluorescent tags, and the PCR products of these primers were processed through an ABI sequencer. Analysis of polymorphic microsatellites was carried out with the software packages Genescan and Genotyper. Assessment of vine and fruit characters in the segregating mapping population is being carried out for QTL analysis of traits that will contribute to the development of an economically viable cultivar.