Abstract
BackgroundPremature senescence can reduce the yield and quality of crops. WRKY transcription factors (TFs) play important roles during leaf senescence, but little is known about their ageing mechanisms in cotton.ResultsIn this study, a group III WRKY TF, GhWRKY27, was isolated and characterized. The expression of GhWRKY27 was induced by leaf senescence and was higher in an early-ageing cotton variety than in a non-early-ageing cotton variety. Overexpression of GhWRKY27 in Arabidopsis promoted leaf senescence, as determined by reduced chlorophyll content and elevated expression of senescence-associated genes (SAGs). Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays showed that GhWRKY27 interacted with an MYB TF, GhTT2. Putative target genes of GhWRKY27 were identified via chromatin immunoprecipitation followed by sequencing (ChIP-seq). Yeast one-hybrid (Y1H) assay and electrophoretic mobility shift assay (EMSA) revealed that GhWRKY27 binds directly to the promoters of cytochrome P450 94C1 (GhCYP94C1) and ripening-related protein 2 (GhRipen2–2). In addition, the expression patterns of GhTT2, GhCYP94C1 and GhRipen2–2 were identified during leaf senescence. Transient dual-luciferase reporter assay indicated that GhWRKY27 could activate the expression of GhCYP94C1 and GhRipen2–2.ConclusionsOur work lays the foundation for further study of the functional roles of WRKY genes during leaf senescence in cotton. In addition, our data provide new insights into the senescence-associated mechanisms of WRKY genes in cotton.
Highlights
Premature senescence can reduce the yield and quality of crops
Isolation and sequence analysis of GhWRKY27 We previously showed that the GhWRKY27 gene is induced by leaf senescence and highly expressed in senescent leaves based on a transcriptome database [30, 31]
The gene expression profiles of cotton leaves from different senescent stages revealed that GhWRKY27 was induced by leaf senescence and predominantly expressed in the early-ageing cotton variety
Summary
Premature senescence can reduce the yield and quality of crops. WRKY transcription factors (TFs) play important roles during leaf senescence, but little is known about their ageing mechanisms in cotton. It is essential to study the genes involved in Analysis of the senescence-associated transcriptome has shown that the expression of many genes can be strongly induced by leaf senescence Among these genes, WRKY genes constitute the second largest family of transcription factors (TFs), which is smaller only than the family of NAC TFs, strongly demonstrating that WRKY TFs play important roles during leaf senescence [7, 8]. WRKY TFs are named for their conserved WRKY domains and can be classified into three main categories: groups I, II (IIa, IIb, IIc, IId and IIe) and III [9, 10] These TFs can bind to W-boxes in the promoters of target genes to regulate gene expression and
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