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Isolated microspore culture has been implemented in breeding programs to produce doubled haploid (DH) lines and thus accelerates the breeding process. However, low microspore embryogenesis frequency in flowering Chinese cabbage remains a key obstacle to the practical application of this technique. This study aimed to establish an efficient microspore culture protocol for flowering Chinese cabbage that would be applied for heterosis breeding. Microspores of five genotypes, 19AY05, 19AY06, 19AY10, 19AY12, and 19AY15, were successfully induced to produce embryos in NLN-13 medium. Microspores of two genotypes, 19AY05 and 19AY15, were cultivated in NLN-13 medium supplemented with different concentrations (0, 0.01, 0.05, 0.1, or 0.2 mg·L−1) of compound sodium nitrophenol (sodium nitrophenol, 5-nitrophenol) to enhance microspore embryogenesis and plant regeneration without an intervening callus phase. The results showed that 0.05 ~ 0.1 mg· L−1 sodium nitrophenol and 0.01 ~ 0.2 mg· L−1 of 5-nitrophenol significantly promoted the induction of microspore embryogenesis of two genotypes, and the best concentrations required for different genotypes are different. Moreover, 0.1 mg· L−1 sodium nitrophenol can significantly increase the plant regeneration rate of the two genetypes. The 5-nitrophenol at 0.01 mg·L−1 significantly increased rate of embryos directly convert to plant in 19AY15. In addition, the average doubled haploid rates in the five genotypes were close to 63%. Horticultural traits of DH lines from 19AY05 were identified and all of them were self-incompatible lines. They showed a high uniformity and consistency that can be directly used for hybrid breeding. Furthermore, the hybrid combination was prepared with the selected DH lines and the Guangdong nucleus genic sterile line GMS019 to screen the excellent hybrid combination for the flowering Chinese cabbage breeding program. This method accelerates the application of microspore culture in hybrid breeding of flowering Chinese cabbage.
相似文献In this study, two herbaceous peony cultivars with different heat tolerances (‘Fenyunu’ FYN low sensitivity and ‘Qiaoling’ QL high sensitivity) were used as research materials. An integrated view of the factors underlying the decrease in photosynthetic rate under high-temperature (HT) stress was provided by analyzing the biochemical parameters, chloroplast ultrastructure, gas-exchange parameters, chlorophyll fluorescence, and modulated 820 nm reflection of herbaceous peony leaves. The results showed that hydrogen peroxide, superoxide anion, malondialdehyde, and electrical conductivity increased significantly, while the photosynthetic pigments content and photosynthetic capacity decreased significantly in QL than in FYN under HT. The contents of soluble sugars and proline increased greatly in FYN than in QL, while the activity of SOD decreased markedly in QL than in FYN after HT. Compared with FYN, the ultrastructure of QL was more seriously disrupted under HT. Chlorophyll fluorescence analysis showed that HT changed the shapes of OJIP curve, resulting in the increase of K phase and J phase. The PSII acceptor side was more damaged than the donor side, and the electron transfer was seriously blocked. The energy flow in the process of light energy absorption, capture, and electron transfer were significantly changed after HT stress. Meanwhile, PSI was also significantly inhibited, and the coordination of both photosystems decreased. The variation of these parameters in FYN was less than that in QL. These results suggested that FYN featured a more heat-tolerance ability as evidenced by the good performances on the antioxidant system, osmoregulatory capacity, and the thermostability of membranes and photosystems.
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