摘要
天麻(Gastrodia elata)是真菌寄生植物。密环菌侵入初生球茎并在其皮层被消化,营养物供次生球茎生长需要;密环菌不能侵染生长小的次生球茎。我们从初生球茎分离并纯化了几丁质酶和β—1,3—葡聚糖酶,分子量各为31.5 kD和94kD,得率各为0.8和0.4 mg/100 g鲜重。纯化几丁质酶的内切酶比活为208 nmol GlcNAc s^(-1)mg^(-1),外切酶比活为4.1 nmol GlcNAcs^(-1)mg^(-1);纯化葡聚糖酶比活为546 nmol Glc s^(-1)mg^(-1)。以相同鲜重计,初生球茎中二种酶的总活性各为次生球茎的34和56倍;这主要是由于次生球茎的酶比活性很低。二种酶对平板上培养的木霉菌丝的生长均有抑制作用,但抑菌活性均较天麻抗真菌蛋白(GAFP)低。我们认为这两种酶在天麻初生球茎消化密环菌菌丝的过程中起重要作用,而对天麻球茎阻止和限制密环菌侵染的抗菌作用贡献甚少,后者主要属于天麻抗真菌蛋白。
Gastrodia data is a plant parasitic on fungi Armillariella mellea. The mycelia infect the primary corm of the plant, and are arrested and digested by the corm at its cortex layer; the released nutrients are mainly transported to the secondary corm which can prevent the infection of the fungus. We isolated and purified the chitinase and β-1, 3-glucanasc from corms by gel filtration and chromatography on hydroxyapatite column with a yield of 0.8 and 0.1 mg/100 g fresh weight of primary corm. On SDS-PAGE, the relative molecular weights are 31.5 kD and 94 kD respectively. The endochitinase and exochitinasc specific activities of the purified chitinase are 208 and 4.1 nmol GlcNAcs-1 mg-1 respectively; the specific activity of the β-l,3-glucarasc is 546 nmol Glcs-1mg-1. On a basis of equal fresh weight, the total enzymatic activities of both enzymes in secondary corm are 34 and 56 times, respectively, less than those in primary corm, mainly due to the much less specific activities of both enzymes from secondary corm, which may be in an inactive state. Both hydrolases in primary corm are shown to have the activities of inhibiting the growth of Trichoderma viride on plates, but in about 7-25 times less than the antifungal activity of Gastrodia Antifungal Protein (GAFP) from the same corm with a yield of 4 mg/100g fresh weight. It is thought that the high enzymatic activities of the two hydrolases in primary corm are induced by the infection of fungus, they are important enzymes taking part in the degradation process of fungus in corms, but give much less contribution to the antifungal function of corms than GAFP.
出处
《云南植物研究》
CSCD
1990年第4期421-426,共6页
Acta Botanica Yunnanica
基金
国家自然科学基金资助项目
关键词
天麻
几丁质酶
葡聚糖酶
Gastrodia etata
Chitinase
β-1,3-glucanase
