Analysis Of AP2/ERF Gene Family And Expression Of DREB Transcript Factors In Phyllostachys Edulis

Moso bamboo(Phyllostachys edulis) is a fast-growing non-timber forest species with the highest ecological, economic and social values of all bamboos in Asia. The AP2/ERF transcription factor family, one of the largest families unique to plants, performs a significant role in terms of regulation of growth and development, and responses to biotic and abiotic stresses. In this paper, based on the draft genome of moso bamboo, we analyzed the AP2/ERF gene family, studied the expression difference of DREB transcription factors under different abiotic stresses, and isolated two DREB genes and verified their fuctions. The main results were as follows:(1) In total, 116 AP2/ERF transcription factors were identified in moso bamboo. The phylogeny analyses indicated that the 116 AP2/ERF genes could be divided into three subfamilies: AP2, RAV and ERF; and the ERF subfamily genes were divided into 11 Groups. The gene structures, exons/introns and conserved motifs of the PeAP2/ERF genes were analyzed. Analysis of the evolutionary patterns and divergence showed the PeAP2/ERF genes underwent a large-scale event of copy around 15 million years ago(MYA) and the division time of AP2/ERF family genes between rice and moso bamboo was 15–23 MYA. We investigated the putative promoter regions of the PeDREBs and discovered that numerous stress-related cis-elements existed in these genes.(2) Further analysis of expression patterns of PeDREBs revealed that most of these genes were strongly induced by drought, low-temperature and/or high salinity stresses in roots and, in contrast, most PeDREB genes had negative functions in leaves under the same respective stresses. In this study, there were two main interesting points: there were fewer members of the PeDREB subfamily in moso bamboo than in other plants and there were differences in DREB gene expression profiles between leaves and roots triggered in response to abiotic stress.(3) In our study, two novel DREB genes, PeDREB2 A and PeDREB1A(Gene ID No. PH01000046G1730 and PH01000668G0350), isolated from moso bamboo by amplified with polymerase chain reaction(PCR), were identified and characterized, the length of CDS were 795 bp and 825 bp, respectively. The PeDREB2 A and PeDREB1 A proteins were estimated to have a typical AP2/ERF domain, molecular weight of 28.96 kDa and 28.84 kDa, isoelectric point of 9.47 and 5.34, respectively. RT-PCR analysis revealed that PeDREB2 A and PeDREB1 A were tissue-specific genes, expressing in leaves, young stems and roots, and expression levels were similar in leaves and young stems. The qRT-PCR analysis displayed, in leaves, the PeDREB2 A transcription levels rapidly accumulate following exposure to drought stress and salt treatment, peaking at 12 h and 0.5 h, respectively, but only very low expression levels were observed under cold stress; the PeDREB1 A was strongly responded to cold stress, 3 h reached to the peak, but slightly responded to drought stress and salt treatment; in roots, transcripts of PeDREB2 A were down-regulated under these three stress treatments, and the expression of PeDREB1 A was initially raised, then dropped under these three abiotic stresses.(4) Overexpression of PeDREB2 A or PeDREB1 A gene in Arabidopsis showed that the transgenic plants have several characterization of cold and salt resistance in culture mediums, for example, the transgenic plants leaves still remain green under cold condition, and the transgenic plant seeds is speedly germination and seedings has a relative large number of lateral roots.This study is a firm foundation for revealing the molecular mechanism of moso bamboo stress tolerance, the information produced from this study may be valuable in overcoming challenges in cultivating moso bamboo.