Abstract
BackgroundBasic region/leucine zipper (bZIP) transcription factors perform as crucial regulators in ABA-mediated stress response in plants. Nevertheless, the functions for most bZIP family members in tomato remain to be deciphered.ResultsHere we examined the functional characterization of SlbZIP1 under salt and drought stresses in tomato. Silencing of SlbZIP1 in tomato resulted in reduced expression of multiple ABA biosynthesis- and signal transduction-related genes in transgenic plants. In stress assays, SlbZIP1-RNAi transgenic plants exhibited reduced tolerance to salt and drought stresses compared with WT plants, as are evaluated by multiple physiological parameters associated with stress responses, such as decreased ABA, chlorophyll contents and CAT activity, and increased MDA content. In addition, RNA-seq analysis of transgenic plants revealed that the transcription levels of multiple genes encoding defense proteins related to responses to abiotic stress (e.g. endochitinase, peroxidases, and lipid transfer proteins) and biotic stress (e.g. pathogenesis-related proteins) were downregulated in SlbZIP1-RNAi plants, suggesting that SlbZIP1 plays a role in regulating the genes related to biotic and abiotic stress response.ConclusionsCollectively, the data suggest that SlbZIP1 exerts an essential role in salt and drought stress tolerance through modulating an ABA-mediated pathway, and SlbZIP1 may hold potential applications in the engineering of salt- and drought-tolerant tomato cultivars.
Highlights
Basic region/leucine zipper transcription factors perform as crucial regulators in Abscisic acid (ABA)-mediated stress response in plants
Among numerous Transcription factor (TF) families, the Basic region/leucine zipper (bZIP) TF family, known as ABA-response element binding factors (AREB) or ABA responsive element (ABRE) binding factor (ABF) (ABRE-binding factors) has been isolated [5]. bZIP proteins are bipartite in structure containing DNA binding domains consisting of abundant basic amino acids that bind to DNA, and leucine zippers characterized by leucine residues spaced regularly at seven amino acid intervals [6]
The results exhibited that SlbZIP1 expression was relatively high in roots, mature leaves and sepals, but moderate to weak signals were observed in stems, flowers and fruits (Fig. 1a)
Summary
Basic region/leucine zipper (bZIP) transcription factors perform as crucial regulators in ABA-mediated stress response in plants. Transcription factors (TFs) are pivotal regulatory proteins in signal transduction networks activated in plants response to various stresses [2]. TFs often bind to specific cis-elements in the promoters of many genes to regulate their expression thereby enhancing stress tolerance [4]. Among numerous TF families, the bZIP TF family, known as ABA-response element binding factors (AREB) or ABF (ABRE-binding factors) has been isolated [5]. Correlative research has indicated that ABA-dependent bZIP TFs generally bind to a conserved sequence with an ACGT core cis-element, Zhu et al BMC Plant Biology (2018) 18:83 especially A-box (TACGTA), ABRE (ACGTGG/TC), Cbox (GACGTC) and G-box (CACGTG) [7, 8]
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