Differential expression of genes associated with phenolic compounds in galls of Quercus castanea induced by Amphibolips michoacaensis

Secondary metabolites related to plant defense against natural enemies and enzymes involved in their biosynthesis vary during gall development. We assessed the differential gene expression related to defensive metabolites in cynipid wasp galls of Quercus castanea induced by Amphibolips michoacaensis throughout gall development. We assembled de novo transcriptomes from galls in three phases of growth and compared the differential expression of phenolic-related genes. We found that (1) Phenylalanine ammonia lyase (PAL) enzyme genes were upregulated at the intermediate and late growth stages. (2) Phenylpropanoid genes were upregulated at the intermediate stage and downregulated at the late stage. (3) Lignin genes were upregulated at the late stage. The transcriptomic profile of wasp galls exposes the switches in secondary metabolism during development. Patterns of differential expression shown in wasp galls suggest phenotype manipulation by the wasp larvae and physiological constraints of the host plant for enzyme channeling in different biosynthetic branches of phenolic compounds.