Table_1_An uncharacterized gene Lb1G04794 from Limonium bicolor promotes salt tolerance and trichome development in Arabidopsis.docx

Halophytes can grow and reproduce in high-salinity environments, making them an important reservoir of genes conferring salt tolerance. With the expansion of saline soils worldwide, exploring the mechanisms of salt tolerance in halophytes and improving the salt tolerance of crops have become increasingly urgent. Limonium bicolor is a halophyte with salt glands that secrete excess Na+ through leaves. Here, we identified an uncharacterized gene Lb1G04794, which showed increased expression after NaCl treatment and was high during salt gland development in L. bicolor. Overexpression of Lb1G04794 in L. bicolor showed promoted salt gland development, indicating that this gene may promote salt gland differentiation. Transgenic Arabidopsis strains overexpressing Lb1G04794 showed increased trichomes and decreased root hairs under normal conditions. Compared with wild type (WT), root growth in the transgenic lines was less inhibited by NaCl treatment. Transgenic seedlings accumulated less fresh/dry weight reductions under long-term salt treatment, accompanied by lower Na+ and malondialdehyde accumulation than WT, indicating that these transgenic lines behave better growth and undergo less cellular damage under NaCl stress. These results were consistent with the low expression levels of salt-tolerance marker genes in the transgenic lines upon salt stress. We conclude that the unknown gene Lb1G04794 positively regulated salt gland development, and promoted salt tolerance of Arabidopsis, offering a new direction for improving salt tolerance of non-halophytes and crops.

盐生植物（halophytes）可在高盐环境中生长繁殖，是蕴藏耐盐相关基因的重要资源库。随着全球盐碱地面积持续扩张，解析盐生植物的耐盐分子机制并提升作物耐盐性已成为愈发紧迫的研究课题。二色补血草（Limonium bicolor）是一类具有盐腺的盐生植物，可通过叶片分泌过量钠离子（Na+）。本研究中，我们鉴定得到一个功能尚未被解析的基因Lb1G04794：该基因在NaCl处理后表达量上调，且在二色补血草盐腺发育阶段呈现高表达特征。在二色补血草中过表达Lb1G04794可显著促进盐腺发育，提示该基因可能正向调控盐腺分化。正常培养条件下，过表达Lb1G04794的转基因拟南芥（Arabidopsis）株系表皮毛数量显著增加，根毛数量明显减少。与野生型（wild type, WT）相比，转基因株系的根系生长在NaCl处理下受抑制程度显著降低。长期盐胁迫处理下，转基因幼苗的鲜重/干重降幅更小，且与野生型相比，其体内钠离子与丙二醛（malondialdehyde）的积累量更低，这表明转基因株系在NaCl胁迫下生长状态更佳，细胞损伤程度更低。上述结果与盐胁迫下转基因株系中耐盐标记基因低表达的现象相符。综上，本研究证实未知基因Lb1G04794可正向调控盐腺发育，并提升拟南芥的耐盐性，为非盐生植物与作物的耐盐性改良提供了全新的研究方向。