Identification of a drought- and cold-stress inducibleWRKYgene in the cold-hardyCitrusrelativePoncirus trifoliata

Abstract

WRKY transcription factors (TFs) are involved in regulation of abiotic and biotic stress responsive genes and play a role in abiotic and biotic stress tolerance in plants. Although commercial Citrus species are sensitive to cold and drought stresses, an interfertile Citrus relative, Poncirus trifoliata, is resistant to cold and more drought tolerant than most commercial Citrus cultivars. An expressed sequence tag clone sharing homology with WRKY-type TFs was previously isolated from a cDNA library constructed using two-day cold-acclimated P. trifoliata cv. Rubidoux seedlings. In this study, a full-length sequence of this WRKY gene was cloned and isolated from 2-day cold-acclimated P. trifoliata plants using the rapid amplification of cDNA ends (RACE) method. The full-length PtrWRKY1 cDNA is 1807 bp and encodes a polypeptide of 405 amino acids containing a single WRKY domain with a Cys 2 His 2 motif, which is a signature of WRKY TFs. A homologous open reading frame (ORF) sequence was isolated from Citrus grandis, CgWRKY1, sharing 98% identity at the nucleotide level with PtrWRKY1. The expression of PtrWRKY1 and CgWRKY1 was investigated in response to cold and drought stresses by northern blot analysis. While the expression of both genes was induced in response to drought, only PtrWRKY1 expression was induced in response to cold. This differential expression in cold-hardy Poncirus and cold-sensitive pummelo suggests that PtrWRKY1 gene may play a role in adaptation and tolerance to cold stress in Poncirus.

Elucidating cold acclimation pathway in blueberry by transcriptome profiling

“…In both libraries, the seven most highly represented TF families were WRKY, ARF, C3H, AP2/ERF, bHLH, C2H2, and NAC. Although these families play diverse roles in plant developmental processes and environmental responses, most of them have been reported to be linked to cold stress resistance in plants (Hu et al, 2008;Liu and Hu, 2013;Rushton et al, 2010;Şahin-Çevik and Moore, 2013). Another three families (bZIP, CO-like and MYB) accounted for 70% of the total number of TFs detected in Library 397´.…”

Characterization of Citrus WRKY transcription factors and their responses to phytohormones and abiotic stresses

“…As WRKYs are considered as one of the master regulators for molecular reprogramming to enhance stress tolerance of plants, it would be very valuable to get knowledge on WRKY citrus family. However, up to date there are only a few articles concerning to these TFs in the citrus relatives Poncirus trifoliata and Fortunella crassifolia (Gong et al 2015, Şahin-Çevik 2012, Şahin-Çevik and Moore 2013 .…”

In silico genome-wide identification and phylogenetic analysis of the WRKY transcription factor family in sweet orange (Citrus sinensis)

“…Brazil is the major worldwide producer of orange, and together with the USA, was responsible for more than 50% of the production in 2014 (USDA, 2015). However, orange production in Brazil is subject to regular fluctuations, which can be explained by the adverse effects of climatic conditions (Sahin-Cevik and Moore, 2013;Ito et al, 2014). Therefore, considering the importance of WRKYTFs in the response to different stresses and the fact that few studies have characterized this gene family in C. sinensis, we identified and characterized WRKY TFs utilizing a computational approach.…”