3种抗褐化剂影响水曲柳体胚发生的生理分析

水曲柳体胚发生过程中往往伴随褐化现象的产生，并且大多体胚生长在褐化的外植体上，为解析外植体褐化和体胚发生之间的联系，本研究通过在培养基中添加PVP（聚乙烯毗咯烷酮）、L-Glu（L-谷氨酸）和AgNO₃（硝酸银），探究其对外植体褐化、体胚发生和生理生化的影响。研究结果表明：（1）低浓度（0.1、0.5 g·L^-1）PVP和100 mg·L^-1 L-Glu处理加剧了外植体褐化，但显著促进了体胚发生，并且体胚发生率高达60%以上（分别比对照组提高了6.59%、24.08%和22.88%）；（2）200 mg·L^-1 L-Glu处理有效降低了外植体褐化，褐化率为68.11%（相比对照组降低了5.83%），但是体胚发生率降低，其发生率为46.32%（相较于对照组降低了22.8%）；（3）3种抗褐化剂处理后外植体细胞内的多酚氧化酶活性（PPO）和超氧化物歧化酶（SOD）活性均低于对照组，过氧化物酶（POD）活性和丙二醛（MDA）含量均高于对照组。因此，研究表明低浓度的抗褐化剂可以促进体胚发生，在这个过程中涉及到POD活性升高和MDA含量增加。本研究为解析水曲柳体胚发生伴随外植体褐化的生物学机理以及水曲柳体胚高频发生提供理论依据。

Physiological Analysis of Three Anti-Browning Agents Affecting Somatic Embryogenesis in Fraxinus mandshurica

The somatic embryogenesis of Fraxinus mandshurica Rupr. is often accompanied by browning, and most somatic embryos grow on browning explants.We analyzed the relationship between explant browning and somatic embryogenesis, by adding PVP(polyvinylpyrrolidone), L-Glu(L-glutamic acid) and AgNO₃(silver nitrate) to the culture medium, and studied its effects on browning, somatic embryogenesis and physiological and biochemical characteristics of explants.The results showed that: (1)Low concentration(0.1 and 0.5 g·L^-1) PVP, and 100 mg·L^-1 L-Glu treatment exacerbated browning of explants, but significantly promoted somatic embryogenesis, somatic embryogenesis rate exceeded 60%(increased by 6.59%, 24.08% and 22.88% compared to the control,respectively). (2)The 200 mg·L^-1 L-Glu treatment effectively reduced the browning of explants, the browning rate was 68.11%(down 5.83% compared with the control), but the somatic embryogenesis rate was reduced to 46.32%(down 22.8%compared with the control). (3)The activities of polyphenol oxidase(PPO) and superoxide dismutase(SOD) in explants were lower than those of control after treatment with three anti-browning agents, peroxidase(POD) activity and malondialdehyde(MDA) content were higher than the control.Therefore, it is believed that a low concentration of anti-browning agent can promote somatic embryogenesis, and in this process, an increase in POD activity and an increase in MDA content are involved. We analyzed the biological mechanism of somatic embryogenesis with explants browning and got the frequency of somatic embryogenesis of F.mandshurica.