Genome-wide identification of the VQ gene family from Limonium bicolor and functional characterization of LbVQ6 under salt stress

VQ motif-containing proteins are recognized as key regulators involved in plant growth, development, and responses to environmental stresses. Despite their established roles in various plant species, this gene family remains insufficiently characterized in Limonium bicolor, a recretohalophytic species notable for its multicellular salt glands. In the present study, 6 LbVQ genes were systematically identified from the L. bicolor genome and classified into four phylogenetic groups. Analyses of gene structure and conserved motifs revealed a high degree of conservation among LbVQ family members. Chromosomal mapping indicated an uneven distribution of these genes across 4 chromosomes. Promoter region analysis uncovered numerous cis-acting elements related to hormonal and stress-responsive pathways. Analysis of expression patterns demonstrated that the majority of LbVQ genes exhibited elevated expression during early salt gland development, suggesting their involvement in salt secretion mechanisms. Among them, LbVQ6 displayed significant differential expression under salt treatment. Functional validation through transient gene silencing experiments indicated that LbVQ6 positively regulate the development of salt glands and the salt tolerance of this species. Collectively, these findings establish a foundation for understanding the regulatory roles of VQ genes in halophytes, particularly in salt stress adaptation.