热激处理对蝴蝶兰组培褐变的抑制及其生理机制

以蝴蝶兰品种Phalaenopsis amabilis BL.‘Jude Butterfly’（B3）组培苗为材料，研究了热激处理对蝴蝶兰叶片外植体组培褐变程度、酚类物质及活性氧代谢相关生理指标的影响，初步探讨了热激处理抑制蝴蝶兰组培褐变的生理机制。结果表明:经热激处理的蝴蝶兰叶片外植体组培褐变程度明显减轻，总酚含量、苯丙氨酸解氨酶（PAL）及多酚氧化酶（PPO）活性降低，但对过氧化物酶（POD）活性的抑制效果不明显，说明热激处理通过降低组培叶片的PAL及PPO活性，抑制酚类物质合成及氧化，从而减少褐变产物——醌类物质的形成；另一方面，热激处理可在短时间内提高抗氧化酶活性（主要是超氧化物歧化酶（SOD）和抗坏血酸过氧化物酶（APX）），进而减少丙二醛（MDA）和过氧化氢（H2O2）的产生，保护了细胞膜结构的完整性，最终有效抑制褐变发生。 

Inhibitory effects and its physiological mechanism of heat shock on tissue culture browning in Phalaenopsis.

In order to find out the physiological mechanisms of heat shock on explant browning in Phalaenopsis, the effects of heat shock on browning degree, the parameters of phenolic and reactive oxygen metabolism were investigated, which employed P. amabilis BL.‘Jude Butterfly’（B3）tissue culture seedling as the experimental material. The results showed that browning degree of leaf explants decreased significantly after heat shock. Moreover, total phenolic content and activities of phenylalanine ammonialyase (PAL) and polyphenol oxidase (PPO) were also lower than the control, it suggested that heat shock treatment effectively alleviated the tissue culture browning by reducing the activities of PAL and PPO in leaf explants of Phalaenopsis, which inhibited the synthesis and oxidation of phenolic compounds, and then decreased quinones content for browning. However, inhibitory effect of heat shock on peroxidase (POD) activity was not obvious. On the other hand, heat shock treatment could affect the oxidative system by means of promoting the activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX) of leaf explants, which led to the decrease of malondialdehyde (MDA) and hydrogen perodixe (H2O2) content, thus protected the cell memberance stability. So it infers that heat shock treatment can effectively suppress tissue culture browning in Phalaenopsis.