Transcriptome-based Discovery of AP2/ERF tRanscription Factors and Expression Profiles Under Herbivore Stress Conditions in Bamboo (Bambusa emeiensis)

Bambusa emeiensis is one of the most economically important bamboos, yet the yield and quality of this bamboo species continue to be challenged by insect herbivores. APETALA2/ethylene responsive factors (AP2/ERF) comprise a large family of plant transcription factors regulating numerous biological processes and playing critical roles in plant defence responses. In the present study, 47 AP2/ERF genes were identified and classified in the B. emeiensis herbivore-induced transcriptome. Based on AP2 domain numbers, conserved amino-acid residues, motif analyses and phylogenetic trees and BeAP2/ERF proteins were grouped into four subfamilies, namely AP2, ERF, Dehydration-responsive-element-binding (DREB) and Soloist, and these subfamilies consisted of nine, 23, 14 and 1 proteins, respectively. Amino-acid residue sequences of the AP2 domain in B. emeiensis were conserved compared with those in Arabidopsis thaliana. Expression analyses revealed that the treatment (herbivore damage) and control groups exhibited different expression patterns, and majority of BeERF/DREB genes were significantly and differentially expressed in the transcriptome, as verified using quantitative real-time PCR (qPCR). Finally, eight genes were selected for further PCR analyses of tissue-specific expression, of which the four tissues exhibited different expression patterns. Our data indicated that the genes encoding the ERF/DREB subfamily of B. emeiensis play critical roles in its response to herbivores.