Abstract
WRKY transcription factors are known to play important roles in plant responses to various abiotic and biotic stresses. The grape WRKY gene, WRKY3 was previously reported to respond to salt and drought stress, as well as methyl jasmonate and ethylene treatments in Vitis labrusca × V. vinifera cv. ‘Kyoho.’ In the current study, WRKY3 from the ‘Kyoho’ grape cultivar was constitutively expressed in Arabidopsis thaliana under control of the cauliflower mosaic virus 35S promoter. The 35S::VlWRKY3 transgenic A. thaliana plants showed improved salt and drought stress tolerance during the germination, seedling and the mature plant stages. Various physiological traits related to abiotic stress responses were evaluated to gain further insight into the role of VlWRKY3, and it was found that abiotic stress caused less damage to the transgenic seedlings than to the wild-type (WT) plants. VlWRKY3 over-expression also resulted in altered expression levels of abiotic stress-responsive genes. Moreover, the 35S::VlWRKY3 transgenic A. thaliana lines showed improved resistance to Golovinomyces cichoracearum, but increased susceptibility to Botrytis cinerea, compared with the WT plants. Collectively, these results indicate that VlWRKY3 plays important roles in responses to both abiotic and biotic stress, and modification of its expression may represent a strategy to enhance stress tolerance in crops.
Highlights
Plants are regularly exposed to a broad range of abiotic and biotic stresses, such as drought, high salinity, extreme temperatures, and pathogen infection (Mishra et al, 2015)
We examined the putative roles of WRKY3 from ‘Kyoho’ grape in resistance to abiotic and biotic stresses by over-expressing the gene in A. thaliana and characterizing the responses of the resulting transgenic plants to drought and salt stresses, as well as to inoculation with Golovinomyces cichoracearum, and B. cinerea
A phylogenetic tree was produced through analysis the VlWRKY3 protein sequence and its orthologs from a range of plant species, and two clades were contained in the phylogenetic tree, each of which contained sequences from monocotyledonous or dicotyledonous species (Supplementary Figure S1A)
Summary
Plants are regularly exposed to a broad range of abiotic and biotic stresses, such as drought, high salinity, extreme temperatures, and pathogen infection (Mishra et al, 2015). These stresses, which can occur concurrently, affect growth and development, can alter species distribution (Shi et al, 2014). The conserved WRKY domain is essential for recognizing and binding to a DNA cis-element, named the W-box, in the promoter regions of target genes (Sun et al, 2003)
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