The Identification Of Quantitative Trait Loci Controlling Rice Mature Seed Cultureability Using Chromosomal Segment Substitution Lines

Tissue culture and genetic transformation are the basic procedures presently employed in plant biotechnology and physiology research, and they have also been widely applied for improving plant varieties. To a large extent, genetic transformation efficiency of a rice variety depends on its tissue culture ability. This in vitro culturability has proven significantly different between indica and japonica varieties. The japonica rice is easily amenable to a highly efficient tissue-culture system, which has greatly accelerated the development of the transgenic lines. In contrast, indica variety is relatively more recalcitrant to tissue culture, and consequently its genetic transformation has been very difficult.Plant regeneration and induction of embryonic calli from cultured tissues, has been showed to be influenced by genotype, the physiological satus of donor plant, the culture medium and the interactions between them. The genotype and the physiological satus of donor plant was the most important limiting factor. So the genes associated with the culturability could be identified through marker assisted selection, and the trait for higher culture ability can be transferred from one variety to the other.This study aimed to map the quantitative trait locus (QTLs) of mature seed culturability using a chromosomal segment substitution lines (CSSL) population derived from a cross between an indica variety "Zhenshan 97B" and a japonica variety "Nipponbare". These CSSLs consist of 139 lines each containing a single or a few introgression segments, and together covering the whole "Nipponbare" genome. Every CSSL was tested by culturing on the two medium systems developed for the respective indica and japonica parental varieties. The performance of culturability was evaluated by four indices: frequency of callus induction (CIF), callus subculture capability (CSC), frequency of plant regeneration (PRF) and the mean plantlet number per regenerated callus (MNR). All four traits displayed continuous variation among CSSL. With the culture system for japonica rice, 21 CIF QTLs, 6 CSC QTLs, 1 PRF QTLs and 11 MNR QTLs were detected. With the culture system for indica variety, 12 CIR QTLs, 8 CSC QTLs, 2 PRF QTLs and 6 MNR QTLs were identified, and these QTLs distributed on 12 rice chromosomes. Three QTLs of CIF and four QTLs of CSC were detected in both the japonica and indica rice culture system. The correlation coefficients of all the four traits varied depending on the culture systems.