Expression and Functional Analysis of WRKY Transcription Factors in Chinese Wild Hazel, Corylus heterophylla Fisch

Abstract

Plant WRKY transcription factors are known to regulate various biotic and abiotic stress responses. In this study we identified a total of 30 putative WRKY unigenes in a transcriptome dataset of the Chinese wild Hazel, Corylus heterophylla, a species that is noted for its cold tolerance. Thirteen full-length of these ChWRKY genes were cloned and found to encode complete protein sequences, and they were divided into three groups, based on the number of WRKY domains and the pattern of zinc finger structures. Representatives of each of the groups, Unigene25835 (group I), Unigene37641 (group II) and Unigene20441 (group III), were transiently expressed as fusion proteins with yellow fluorescent fusion protein in Nicotiana benthamiana, where they were observed to accumulate in the nucleus, in accordance with their predicted roles as transcriptional activators. An analysis of the expression patterns of all 30 WRKY genes revealed differences in transcript abundance profiles following exposure to cold, drought and high salinity conditions. Among the stress-inducible genes, 23 were up-regulated by all three abiotic stresses and the WRKY genes collectively exhibited four different patterns of expression in flower buds during the overwintering period from November to April. The organ/tissue related expression analysis showed that 18 WRKY genes were highly expressed in stem but only 2 (Unigene9262 and Unigene43101) were greatest in male anthotaxies. The expression of Unigene37641, a member of the group II WRKY genes, was substantially up-regulated by cold, drought and salinity treatments, and its overexpression in Arabidopsis thaliana resulted in better seedling growth, compared with wild type plants, under cold treatment conditions. The transgenic lines also had exhibited higher soluble protein content, superoxide dismutase and peroxidase activiety and lower levels of malondialdehyde, which collectively suggets that Unigene37641 expression promotes cold tolerance.

Identification of the WRKY gene family and functional analysis of two genes in Caragana intermedia

“…Evidence from genome- or transcriptome-wide analyses shows that the response of WRKYs to abiotic stresses varies according to the species. For instance, 30 putative WRKYs were identified through transcriptome analysis in Chinese wild hazel ( Corylus heterophylla Fisch ), and 23 of these WRKYs were found to be simultaneously up-regulated by cold, drought and high-salinity stresses [ 58 ]. Twenty-eight salt-responsive GarWRKYs were identified among 109 WRKY genes in a salt-tolerant wild cotton species ( Gossypium aridum ) based on transcriptome sequencing data [ 59 ].…”

Genome-wide analysis of WRKY gene family in the sesame genome and identification of the WRKY genes involved in responses to abiotic stresses

“…The InterPro Scan 5 analysis suggested that SiWRKY8 and SiWRKY35 are PWRKY transcription factors, which represented a subset of Group IIc probable WRKY transcription factors from plants. PWRKY transcription factors, with the InterPro number IPR017396, were known to regulate various abiotic stress responses [37]. Thus, SiWRKY8 and SiWRKY35 might regulate the biotic and abiotic stress responses.…”

MicroRNA396-mediated alteration in plant development and salinity stress response in creeping bentgrass

“…6). TFs from WRKY family positively regulate salt and other environmental stress tolerance in a variety of plant species 53,54 . MADS and AP2 family TFs are also largely involved in plant abiotic stress resistance 55,56 .…”