| The aim of this study was to develop diversified tetraploid lines of pakchoi and thereby facilitate heterosis breeding. We performed an isolated microspore culture of 16 hybrid varieties of pakchoi and obtained 393 regenerated plants in total. Among these,32 plants were identified as tetraploids based on morphological identification, examination of stomatal characteristics, size measurement and viability testing of pollen, and chromosome counts of the pollen mother. Furthermore,3 tetraploid lines showing excellent characteristics were screened. The 3 selected tetraploid lines were used as parents, and a tetraploid hybrid with significant heterosis and comprehensive quality traits was selected through a variety of comparison tests. Thus, we used isolated microspore culture to establish a technical system for heterosis breeding of tetraploid parental lines of pakchoi. The results are as follows:1. The embryoids of all 16 varieties were obtained to cultivate the microspores. The results of variance analysis showed that the microspore-derived embryos were significantly different. The highest embryo yield 'Caiyuan' is the lowest'JA002'48.7 times, indicating that genotype is an important factor that affects microspore embryos.2.4℃low-temperature pretreatment can increase the frequency of microspore embryogenesis. The optimal treatment time is 24h, pretreatment processing time is too long embryo induction rate decreased.33℃high-temperature pretreatment at the beginning of suspension culture is necessary to embryogenesis, and the optimal treatment time is 24 h.3. It was also observed that certain concentrations of 6-BA and NAA in the NLN-13 medium can improve the microspore embryo induction rate in this experiment, and that 0.05 mg·L-16-BA+0.1-0.2 mg·L-1 NAA resulted in the highest embryo induction rate.4. Shaking cultivation, can promote the development of microspore embryogenesis, increase the incidence of cotyledon embryo and reduce the incidence of abnormal embryos, but can improve the synchronization of embryo development, shorten training time and improve the quality of embryoid bodies, thus improving seeding rate.5. Subculture of microspore plants in the process of using permeable membrane sealing, seedling plants of microspore high vitrification significantly inhibited. MS+30 g·L-1 sucrose +7.5 g·L-1 agar+0.1 mg·L-1 NAA was suitable microspore plant rooting medium.6. The conversion capacity of different varieties to produce tetraploid microspores differed significantly; the highest was'Jinxiashi', at up to 52.63%, followed by'Lijiang', 'Jinpinxiaguan'and'JA001', the four varieties listed above are ideal materials for inducing tetraploid from isolated microspores.7.32 plants were identified as tetraploids based on morphological identification, examination of stomatal characteristics, size measurement and viability testing of pollen, and chromosome counts of the pollen mother.8. Pakchoi microspore plant food groups, haploid, doubled haploid and polyploid exist. Haploid doubling rate of high natural, no artificial double to get a lot of double haploid and polyploid polyploid ratio of 33.16%, the ratio of double-haploid plants of 51.34%.9. Analysis of horticulture characteristic indicates that tetraploid lines obtained in the experiment and the hybrid combinations developed with it are uniform. It also indicates that the tetraploid lines are pure lines. The requirement to uniformity of commercial hybrid can be satisfied by using it as parental lines.10. The results of hybrid crosses and the cell output of their parents. These show that the three testcrosses had obvious heterosis and that in the'10AT24×10AT 11'cross, the strength of heterosis rose to 44.48%. Proved the existence of tetraploid hybrids heterosis, can be used in breeding practice.11.'10AT24×10AT11'not only had significantly higher yields than the control diploid cultivars 'Huawang' and 'Huaguan' and the other two tetraploid hybrids, but the leaves are bright green and cross-pollinates, it has good product quality traits, and it is an excellent pakchoi tetraploid hybrid. |
PDF Full Text Request