The bZIP gene family in the halophyte Limonium bicolor: Identification, expression analysis, and regulation of salt stress tolerance

Abstract

The basic region/leucine zipper transcription factors (bZIPs) are one of the largest transcription factor families in eukaryotes, and play a key role in growth, development, and response to abiotic stresses. Limonium bicolor is a typical recretohalophyte, which can excrete excess salts from body to outside through the salt glands located on the stems and leaves to maintain ionic balance in the body. In this study, 58 L. bicolor bZIP members (LbbZIP1–58) were identified, which were unevenly distributed on 8 chromosomes and divided into 11 groups. The bioinformatics analysis revealed strong colinearity between LbbZIPs and GmbZIPs of soybean (Glycine max). And promoter cis-acting elements of LbbZIPs were related to stress responses and phytohormone responses. Most LbbZIP members responded to abiotic stresses such as NaCl, PEG, and ABA. Silencing LbbZIP28 in L. bicolor increased salt glands density and salt secretion capacity of leaves, and salt tolerance by means of up-regulating the expression levels of genes involved in salt gland development and ion transport. These results provide new information for LbbZIPs and help to interpret salt gland development and salt secretion in L. bicolor. Our results will provide a reference for a deeper understanding of the molecular foundation of LbbZIPs in L.bicolor.