The secondary salinization of saline-alkali land is increasing globally. It is of strategic significance to explore the salt-tolerant molecular mechanism of halophytes and cultivate saline-alkali resistant crops for the improvement of saline-alkali land. The recretohalophyte Limonium bicolor has a unique salt-secreting structure, salt gland, which can directly excrete Na+ out of the body to effectively avoid salt stress. Exploring the development mechanism of salt gland structure in recretohalophyte is of great significance for analyzing the development of plant epidermis structure and improving the salt-resistant mechanism of plants.
Recently, Wang Baoshan/Yuan Fang research group of Shandong Normal University published a research paper titled "Genome-wide identification of bHLH transcription factors and functional analysis in salt gland development of the recretohalophyte sea lavender (Limonium bicolor)"（ https://doi.org/10.1093/hr/uhae036 ). Taking the recretohalophyte Limonium bicolor with multicellular salt gland as the material, based on the analysis of genome data of Limonium bicolor and the report of typical bHLH genes involved in salt gland development, the study systematically identified 187 bHLH family genes in L. bicolor for the first time (Fig. 1), and analyzed their characteristics, chromosome location, gene structure, phylogenetic relationship, promoter regulatory elements and so on in the genome. With the help of transcriptome database, the expression patterns of bHLH family genes in different developmental stages and different stages of salt treatment of L. bicolor were analyzed, and the key role in salt gland development or salt tolerance was explored. In situ hybridization and subcellular localization evidence showed that the protein encoded by bHLH family gene Lb1G07934 was localized in salt glands and expressed in the nucleus (Fig. 1). Through genetic transformation, overexpression lines and knockout mutants of Lb1G07934 were obtained by means of overexpression and CRISPR-Cas9 technology. Lb1G07934 negatively regulated the development, salt secretion and salt resistance of salt glands (Fig. 2). This study is a new attempt to identify the salt gland development and salt resistance gene of L. bicolor, which lays a foundation for further study on the role and functional mechanism of bHLH gene in L. bicolor.
Xi Wang, a doctoral student from Shandong Normal University, is the first author. Professors Baoshan Wang and Fang Yuan from Shandong Normal University are the corresponding authors of the paper. This study was supported by the National Natural Science Foundation of China project.
