Creation And Identification Of DH Lines In Komatsuna And Naibaicai (Brassica Campestris Ssp. Chinensis L.)

At present,the seeds of Komatsuna and Naibaicai sold on the market were the F1 generation,and the variety resources are relatively poor.To obtain hybrid varieties with good characters,the homozygous lines need to be obtained first.The time of obtaining homozygous lines can be greatly reduced by using microspore culture.In this study,microspore culture experiments were performed with 8 cultivars of Komatsuna and 3 commercial hybrid varieties of Naibaicai.The effects of different genotypes on microspore embryogenesis were evaluated.The cotyledonary stage embryoids were transferred,subcultured and rooted.The ploidy of the regenerated plants was identified after transplantation,and the doubled haploid(DH)plants were self-bred.Affinity index was determined to investigate the horticultural traits of DH lines.The selected self-incompatible excellent DH lines were used to prepare hybrid combinations.Horticultural traits and plot yield of hybrid combinations were measured.The results are as follows:1.In the microspore culture of Komatsuna,six of the eight donor plants obtained embryos,and there were significant differences in the induction rates of the six genotypes of Komatsuna,?18SY13‘ with the highest rate of embryo induction was 6.23 embryos per bud,?18SY14‘ embryo induction rate is the lowest,only 0.25 embryos per bud,the difference between the highest and lowest embryo induction rates was 5.98 embryos per bud.There were differences in the number of plant regeneration between the six genotypes,and the directly plant regeneration rate of ?18SY13‘ was 73.34%,which was 52.23% higher than the ?18SY17‘ with the lowest directly plant regeneration rate.After the regenerated plant were transplanted,and the average transplanting survival rate was 95.57%.331 double haploids(DH)lines from 522 plants were obtained.The average double haploid rate was 63.41%,and the highest double haploid rate was 71.33%(18SY13).The self-compatibility index of DH lines was determined.The results showed that flowering affinity index was between 0.05 and 0.22,and the bud stage affinity index was between 2.04 and 2.52.The horticultural traits of 331 DH lines were identified,and it was found that the ?SM002‘ strain was erect and the leaf color,yield were excellent.The self-incompatible line of the Komatsuna screened by the research group was used as the female parent,and the newly created five DH lines were used as the male parent to prepare the hybrid combination.The horticultural traits of hybrid combination ?114‘ was excellent.2.In the microspore culture of Naibaicai,embryos from the three genotypes were all obtained,but there were differences in the embryo induction rates of the three genotgpes of Naibaicai.The highest rate of ?18SY01‘ was 1.92 embryos per bud;the embryo induction rate of ?18SY03‘ is the lowest,only 0.58 embryos per bud,the difference between the highest and lowest embryo induction rates was 3.31 fold.The shake culture not only increased the number of cotyledonary embryos of of Naibaicai,but also accelerated the development of embryos in the culture dish.The plant regeneration of the three genotypes showed different results,it was found that ?18SY02‘ had the highest plant regeneration rate,which can reach 58.62%;?18SY01‘ had the lowest plant regeneration rate,which was only 49.23%.61 regenerated plant were transplanted,58 plants were transplanted significantly,and the survival rate of transplanting was 95.08%.The ploidy of DH lines were identified by morphological identification and flow cytometry,33 DH lines were obtained.The double haploid rate was more than 50%,and ?18SY01‘ has the highest double haploid rate with 60%.The self-compatibility index of DH lines was determined.The results showed that flowering affinity index <0.5 and the bud stage affinity index >2.The horticultural traits of the DH lines obtained from the Naibaicai were measured,it was found that the horticultural traits of ?BM001‘ was better,the leaf color of ?BM002‘and ?BM012‘ was different from other DH lines with light green,and they can grow normally.