天麻中抗真菌蛋白质的诱导和积累

前曾报告从天麻（Ｇａｔｒｏｄｉａ ｅｌａｔａ Ｂｌ）中分离出一种对木霉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；对寄生免疫荧

INDUCTION AND ACCUMULATION OF THE ANTIFUNGAL PROTEIN IN GASTRODIA ELATA

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.