摘要
基于相似性克隆策略和RT-PCR,从兰科植物乌天麻(Gastrodia elataf.glauca)球茎克隆得到两个新的天麻抗真菌蛋白基因,命名为gastrodianin-4A(ga4A)和gastrodianin-4B(ga4B),并首次用Northern杂交研究了该基因在植物不同部位的转录表达。结果表明,天麻个体的不同部位只转录表达同一种Gastrodianin基因,纯化自球茎的Gastrodianin蛋白质的肽质量指纹谱与推导的Ga4A和Ga4B成熟蛋白的氨基酸序列相吻合;Northern杂交证明天麻的地上器官Gastrodianin基因转录表达量远远高于地下球茎,而次生球茎皮层组织的表达量比中柱和整个营繁茎的都高一些。天麻球茎Gastrodianin的外周表达模式可能是天麻在地下抵御蜜环菌(Armillaria mellea Karst)入侵球茎皮层内部的防卫机制之一,但该基因在天麻地上部分的高丰度表达暗示Gastrodianin可能蕴藏其它生理功能。
Through a similarity-based cloning strategy, two types of cDNA clones with complete cDNA sequences matching the known gastrodianins were obtained from Gastrodia elata f. glauca （Orchidaceae） and designated gastrodianin-4A （ga4A） and gastrodianin-4B （ga4B）, respectively. But only one identical isoform was found to be expressed in all different parts of a single plant. The deduced amino acid sequences of ga4A/-4B accord closely with those of the plant-purified gastrodianins based on the peptide mass fingerprinting analysis. RNA gel blot analyses indicate that gastrodianins were much more abundantly expressed in the fnlly-opened flowers than the underground corms where an enhanced expression was found in the out layers of secondary corms. From its expression pattern and level in corms, the gastrodianin is assumed to prevent Armillaria hyphae from growing on secondary corms and retard the further penetration of Armillaria hyphae into nutritive corms. Gastrodianins are therefore considered to play a defensive role against the fungus Armillaria. Given the apparently abundant expression in the above-ground parts of the plant, however, gastrodianins seem unlikely to be limited to such a role.
出处
《云南植物研究》
CSCD
北大核心
2007年第3期345-350,共6页
Acta Botanica Yunnanica
基金
云南省自然科学基金项目(2003C0059M)资助
关键词
天麻抗真菌蛋白
表达
乌天麻
兰科
蜜环菌
Gastrodianin
Expression pattem
Gastrodia elata
Orchidaceae
Armillaria mellea
