Abstract: 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 fully-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 .

Key words: Gastrodianin