Abstract:
Objective To evaluate the influences of the genotypes, anther developmental stages, and cultural conditions on the efficiency of embryogenic callus induction and plant regeneration in the anthers culture of Bupleurum chinense. Methods The different effects such as four genotypes, plant growth regulators, and temperature condition were compared in the experiments. The histological study was performed with the process of the anther culture. Results The highest inducing rate of embryogenic calli were achieved for the genotypes Zhongcaiyihao (ZCYH), Z4, and Z5 at the early- to middle-uninucleate stages, except for genotype ZPM1 at the tetrad stage. Cold pretreatment increased the production of the embryogenic callus, in which 4-day cold pretreatment improved the production of embryogenic callus from 0% to 2.2% and 5.0% for genotypes ZPM1 and ZCYH, respectively. No embryogenic callus was induced in the medium containing less than 0.75 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D). The highest regeneration rate (34.6%) was obtained in 1/2 MS salts regeneration medium supplemented with 0.1 mg/L 6-benzylmaminopurine (BA). The low concentration of BA was able to promote the embryogenic callus formation and subsequent plantlet regeneration via somatic embryogenesis. Chromosome counting of regenerated plantlets showed mostly diploid plant (2n = 12) with only one haploid plant (n = 6). Because of the low rate of microspore embryo formation, we only tracked the process of embryogenesis from the connective tissue, instead of microspore by histological observations. Conclusion This study establishes an efficient system for embryogenic callus induction and plant regeneration system. This is the first report on the haploid plantlet through the anther culture of B. chinense.
