Plant vascular system-feeding Psyllidae (Hemiptera) and Nematoda genomes encode family 12 glycosyl hydrolases

Abstract

Insect-encoded cellulolytic plant cell wall hydrolases have thus far been found mostly from glycosyl hydrolase family 5, 9, 10, and 45. We now report the first evidence for genomic encoding of family 12 glycosyl hydrolases in vascular feeding Psyllidae (Hemiptera) and Nematoda. The genes were identified in three psyllids (Acanthocasuarina muellerianae Taylor, Pachypsylla venusta (Osten-Sacken), and Diaphorina citri Kuwayama) and a root tip feeding dagger nematode (Xiphinema index Thorne and Allen; Dorylaimida: Longidoridae). While the final gene products were highly similar, the genomic intron structure varied, having a 2 kB intron in P. venusta, a 283 base-pair intron in D. citri, and no intron in X. index. Endoglucanase activity was demonstrated using the D. citri genes in an Agrobacterium Conn (Rhizobiaceae) infiltration-based plant expression system. The presence of family 12 endoglucanases in this set of insects suggests a specific role in facilitating feeding on vascular tissue.