【作者】 王浩鑫； 杨涛； 曾英； 胡忠；

【Author】 Wang Haoxin Yang Tao Zeng Ying Hu Zhong State Key Laboratory of Phytochemistry and Plant Resources in West China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, 650204; Graduate School of the Chinese Academy of Sciences, Beijing, 100039

【机构】 中国科学院昆明植物研究所；

【摘要】 基于相似性克隆策略和RT-PCR,从乌天麻(G．elata Bl.f.glauca S.chow)球茎克隆得到两个新的天麻抗真菌蛋白基因并命名为gastrodianin-4A(ga4A)和gastrodianin-4B(ga4B),首次用Northern杂交和mRNA原位杂交研究了该基因在植物体内的时空表达模式。反转录并克隆测序发现天麻个体的不同部位只转录表达其中的一种Gastrodianin,Northern杂交显示天麻的地上成熟器官(包括花葶和成熟小花)的Gastrodianin转录表达量远远高于地下球茎包括营繁茎和次生球茎,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。此外,通过mRNA原位杂交研究了Gastrodianin在营繁茎、次生球茎以及幼嫩花序的表达定位,实验结果表明Gastrodianin在球茎的皮层细胞和维管束细胞中表达,特别是在次生球茎的第二至第八层细胞检测到转录产物的明显积累;同时还观察到Gastrodi- anin在营繁茎的内皮层以及幼嫩花序的苞片和鳞片中表达,但初生球茎的“大型细胞”内没有发现杂交信号。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,因为约1m高的地上成熟器官几乎不可能接触到营腐生生活的蜜环茵。更多还原

【Abstract】 Gastrodia elata B1. is an achlorophyllous orchid plant feeding on the fungus Armillaria mellea. The plant lives underground during its life cycle except for florescence. Gastrodianins, members of the su-perfamily of monocot mannose-binding protein (MBP), have been identified from Gastrodia elata, yet their physiological functions in the plant are rarely understood. Aspects of expression of gastrodianins in growth and development of the plant will be helpful to dissect their functional roles. Two types of cDNA clones with complete cDNA sequences matching the known gastrodianins were obtained from G. elata B1.f.glauca S.chow (Orchidaceae) and designatedgastrodianin-4A (ga4A) and gastrodianin-4B (ga4B), respectively. But only one isoform was found to be expressed in all different parts of a single plant. Based on the RNA gel blot analysis, gastrodianins were much more abundantly expressed in the fully-opened flowers than the underground corms where an enhanced expression was found in the out layers of secondary corms. By RNA in situ hybridization gastrodianin transcripts were distinctly detected in the cortical cells and vascular cells of corms. Strong transcript accumulations were observed in two to eight layers of cortical cells in secondary corms. From its peripheral tissue expression pattern and level in corms and flowers, the gastrodianin may account for a possible defense against phytopathogens or insects.更多还原