The protein content of tissues in cynipid galls (Hymenoptera : Cynipidae):Similarities between cynipid galls and seeds

Cynipid galls are examples of induced plant development, where the gall ind ucer is in control of cell differentiation and morphogenesis of a new plant organ. This study concentrates on the tissues of the larval chamber common to all cynipid galls. The protein content of the inner gall tissue was com pared to that of non-gall plant tissues. We investigated three oak and two rose galls and their respective host plants. Total protein signatures of in ner gall tissues were different from those of non-gall plant tissues, and a mong the five galls. N-terminal sequences were obtained for two abundant pr oteins from the inner gall tissues of D. spinosa and A. quercuscalicis, whi ch were common to all galls, at 62 and 43 kDa. Database queries suggest the 62 kDa protein to be homologous to a protein disulphide isomerase (PDI), a nd the 43 kDa protein to be homologous to NAD-dependent formate dehydrogena se (FDH). A naturally biotinylated protein was detected at 33 kDa during We stern analyses with streptavidin. Western analyses revealed the presence of the biotinylated protein and PDI in the inner gall tissues of all five gal ls, while FDH was only detected in A. quercuscalicis and A. fecundator. PDI was also common to all non-gall tissues, while FDH was not detected in non -gall tissues, and the biotinylated protein was only detected in seeds. The proteins identified in the inner gall tissue suggest that (a) inner gall t issues in some galls are under respiratory stress, and (b) cynipid gall for mation might involve the ectopic expression of seed-specific proteins.