天麻中抗真菌蛋白质的诱导和积累

INDUCTION AND ACCUMULATION OF THE ANTIFUNGAL PROTEIN IN GASTRODIA ELATA

前曾报告从天麻（ＧａｓｔｒｏｄｉａｅｌａｔａＢｌ，）中分离出一种对木霉菌丝生长有强抑制作用的蛋白质，命名为天麻抗真菌蛋白，简称ＧＡＦＰ，也称为Ｇａｓｔｒｏｄｉａｎｉｎ。对不同天麻材料来源的ＧＡＦＰ分析表明：ＧＡＦＰ的相对分子量为１４ｋＤ，等电点可能不同，变动范围８．１—９．３。体外抑菌试验证明ＧＡＦＰ对腐生性真菌如木霉和密环菌等有强抑制活性，半抑制浓度ＩＣ０．５为０．０８ｍｇ／ｍＬ；对寄生性真菌如棉花枯萎病和稻瘟病作用很弱。对球茎生长期中７个阶段ＧＡＦＰ的含量测定和ＧＡＦＰ免疫荧光组织定位观察证明：１．ＧＡＦＰ是营养茎被密环菌侵染诱导而后大量合成的，合成部位可能是大型细胞。２．ＧＡＦＰ由营养茎输送到顶生球茎，积累于皮层细胞中，是皮层细胞的主要蛋白成分。３．营养基衰败后，顶生球茎ＧＡＦＰ的总量下降不多，直至抽苔时转移到花茎中。结果说明ＧＡＦＰ是天麻的一种重要功能蛋白质，是使顶生球茎处于拒菌状态的主要物质。

Gastrodia elata Bl.is a plant belonging to orchid family which is parasitic on fungus Armillaria mellea.The fungal hyphae infect the ancestor or nutritive corms of the plant,but are arrested and digested in the cortical cells.The released nutrients are mainly transported into the terminal coims for its growth.The fungi can never infect into the terminal coim. In 1988 we puri-fied a 14kD protein named Gatrodia Antifungal Protein(GAFP)or gastrodianin,which was showed to be of strong antifungal activity to Trichoderma viride,In this paper we report that the isoelectric point of the 14kD protein may fluctuate from 8.1 to 9.3,depended on material re-sources. The in vitro tests of antifungal activity showed that GAFP inhibites specifically the growth of seprophytic fungi as Armillaria mellea and Trichoderma virlde strongly with a half in-hibition concentration(IC 0.5) of 0.08mg/mL,but inhibites very weakly the parasitic fungi as Fusarium oxysporum f.sp.vasinfectum and Pyricularia oryzae etc. The quantitation of GAFP in corms at 7 stages of a complete period of vegetative propagation and the localization of GAFP in coms by immuno-fluorescence method showed that a stimulating increase in 15 times of GAFP in the nutritive corms is induced by the infection ofungi, probably the induced synthesis happens in the large cells.The GAFP is continually transported to the terminal com and accumulatd in the cortical cells with a high concentration of about 1.5mg/g of fresh tissue that is enough to pre- vent the infection of fungi.After the decay of the nutritive corm most of GAFP in terminal com can maintain till the GAFP is transported into flower stem when the flower bud sprouts.It was deduced that GAFP is an important protein functioning in the defense mechanism of rectricting the infection of Armillaria mellea in Gastrodia elata.