Plant development reprogramming by cynipid gall wasp: proteomic analysis

An insect–plant interaction induced gall formation is where gall wasps change the plant development towards formation of new units to shield and nourish the evolving larvae. The targets of the insect signals and the mechanism of gall development are unknown. To show the molecular pathways that are responsive to the gall wasp, the proteomic approach was used to compare the gall with non-gall plant tissues. We studied three oak gall species (Cynips quercusfolii, Cynips longiventris, and Neuroterus quercusbaccarum) and the host plant (Quercus robur). Among the 21 identified proteins, 18 increased and three decreased in abundance in gall tissue, in comparison to the leaf tissues. Ten proteins were C. quercusfolii responsive, two only with this gall inducer, while seven increased in abundance. Eleven proteins were C. longiventris responsive, and two only with this gall inducer. Sixteen proteins were associated with gall formation by the N. quercusbaccarum and, in this, eight only with this gall inducer. A similar effect on protein abundance occurred as galls in leaf veins (for five proteins). For leaf blades, such a relation was not found. The role of each protein is discussed according to its involvement in the gall formation. Moreover, S-adenosyl methionine synthase, flavone 3-hydroxylase, stress- and pathogenesis-related proteins, and gamma carbonic anhydrase are associated with developmental regulation of plant tissue into a gall.