Identification Of QTLs Associated With Tissue Culture Response Of Mature Embryos Of Synthetic Hexaploid Wheat Lines

Mature embryo is an excellent explant for tissue culture in wheat genetic transformation as it is convenient to obtain without limitation of growing seasons and development stages. However, regeneration ability of the calli from mature embryos is limited, thus hindering its application. To identify genes associated with the tissue culture response (TCR) of wheat, QTLs for callus induction from mature embryos and callus regeneration were detected using a recombinant inbred lines (RILs) population(contains 171 lines) derived from cross between a synthetic hexaploid wheat genotype, SHW-L1 and a commercial cultivar Chuanmai 32(SW8188). The wheat mature embryos for tissue culture were obtained from the seeds harvested in the field and glasshouse, respectively. The main results in this study are as follows:1. Significant relevance between callus rate, differentiation rate and emergence rate were detected. Significant relevance of callus rate among four years was detected.2. The callus rate varied greatly among the RILs and showed a continuous distribution ranging from 0.37 to 1.00 with a mean of 0.67. The differentiation rate of the RIL population gave a continuous distribution with a range of 0.29-0.97 with an average value of 0.70. Emergence rate of the population ranges from 0 to 0.36 with an average of 0.14.Significant differences were not detected for callus rate and differentiation rate between the two presents, SHW-L1 and SW8188. For emergence rate, significant differences between parents were detected with SHW-L1 (0.13) significantly higher than SW8188 (0.03).3. Significant differences were detected for callus rate between seeds harvested in the field and glasshouse. The result indicated that callus rate of the mature embryos collected from the glasshouse showed higher than that from the field.4. Totally, three QTLs for callus rate were identified and they were located on chromosomes 1D,5A, and 6D, respectively, with explained phenotypic variation ranging from 10.16 to 11.82%. Two QTLs for differentiation rate were detected on chromosomes 1A and 3D. with 10.96 and 9.10% of the phenotypic variation, respectively. Two QTLs for emergence rate were identified and they were located on 3B and 4A, respectively, with 9.88 and 10.30% of phenotypic variation. Collectively, the results presented in this study with those reported previously indicated that group 1.3, and 5 chromosomes are likely to play important roles in TCR of wheat crops.