An uncharacterized gene Lb1G04794 from Limonium bicolor promotes salt tolerance and trichome development in Arabidopsis

Abstract

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.

The RING zinc finger protein LbRZF1 promotes salt gland development and salt tolerance in Limonium bicolor

“…In addition to LbRZF1 , other genes affecting salt glands have been identified. For example, overexpressing the gene Lb1G04794 with unknown function in L. bicolor resulted in an increase in the number of salt glands (Jiao et al, 2022). At the base of the L. bicolor leaf petiole, gene‐edited mutants of the transcription factor gene LbNAC4 produced only two or three foci compared with the normal four fluorescent foci seen in the WT; conversely, the salt glands of lines overexpressing LbNAC4 had six foci and increased salt gland density (Zhao et al, 2023a).…”

“…In fact, several genes from L. bicolor result in greater salt tolerance when heterologously expressed in Arabidopsis. For example, overexpression of Lb1G04794 in Arabidopsis represses root hair development and increases salt tolerance (Jiao et al, 2022). Overexpression of Lb1G04202 increases tolerance to salt during the germination of transgenic Arabidopsis (Wang et al, 2022b).…”

Agrobacterium rhizogenes-Mediated Genetic Transformation and Establishment of CRISPR/Cas9 Genome-Editing Technology in Limonium bicolor

“…As for Lb1G04794, it was only the phenotype associated with salt glands that was analyzed in the 35S::Lb1G04794 L. bicolor. The further function of Lb1G04794 in salt stress was analyzed in detail in Arabidopsis [13]. These results indicate that functional analyses of genes of interest have still been carried out via heterologous expression in Arabidopsis.…”

“…Overexpression of Lb1G04202 in Arabidopsis resulted in increased salt tolerance by promoting proline biosynthesis [12]. When an uncharacterized gene Lb1G04794 was overexpressed in Arabidopsis, transgenic Arabidopsis showed that the number of trichomes was increased, root hairs were decreased, and salt resistance was enhanced [13]. Overexpression of an R1-type MYB transcription factor LbMYB48 in Arabidopsis has been shown to increase salt tolerance through maintaining ion and osmotic balance and might be involved in the abscisic acid signaling pathway [14].…”