Abstract
Sheepgrass is a perennial native grass species in China, and it can tolerate high levels of salt stress with an aggressive and vigorous rhizome system. Many salt-stress-responsive genes have been identified in sheepgrass. In this study, we report the cloning and characterization of a novel salt-induced gene, LcSAIN3 (Leymus chinensis salt-induced 3), from sheepgrass. Expression analysis confirmed that LcSAIN3 was induced by PEG, ABA, and salt treatments, and the expression of LcSAIN3 was significantly increased in salt-tolerant germplasms under salt treatment. Subcellular localization analysis indicated that the GFP-LcSAIN3 protein was mainly localized in the chloroplasts. The heterologous expression of LcSAIN3 in Arabidopsis increased the seed germination rate of transgenic plants under salt, ABA, and mannitol treatments. The seedling survival rate, plant height, and fresh weight of the transgenic plants were higher than those of WT plants under salt stress. The overexpression of LcSAIN3 caused a relatively high accumulation of free proline, enhanced SOD activity, and led to the upregulation of several stress-responsive genes such as AtRD26, AtRD29B, AtSOS1, and AtP5CS1. These results suggest that LcSAIN3 could be a potential target for molecular breeding to improve plants’ salt tolerance.
Highlights
Soil salinization is a severe problem that affects plant growth, development, and productivity worldwide [1]
Previous studies have suggested that the transcription factors can activate many stress-induced genes, such as LEA genes (RD26, RD29A, RD29B, and RAB18) and proline biosynthesis genes (P5CS), and that LEA proteins are mainly involved in protection to desiccation by acting as cellular dewatering protectants under stress conditions
Our results indicate that LcSAIN3 overexpression in Arabidopsis could promote proline content and superoxide dismutase (SOD) activity under overexpression in Arabidopsis could promote proline content and SOD activity under salt salt stress
Summary
Soil salinization is a severe problem that affects plant growth, development, and productivity worldwide [1]. Biochemical, cellular, and molecular processes in plants under salt stress have been investigated by many researchers [2,4,5,6,7], while genetic sources for salt tolerance development in crops have been studied [8]. Extensive numbers of transcription-factor-encoding genes have been identified in response to salt stress, including DREB, bZIP, NAC, and MYB family genes [9,10,11,12,13], and overexpressing these genes can enhance salt stress tolerance in transgenic plants [2,14,15,16,17]. Previous studies have suggested that the transcription factors can activate many stress-induced genes, such as LEA genes (RD26, RD29A, RD29B, and RAB18) and proline biosynthesis genes (P5CS), and that LEA proteins are mainly involved in protection to desiccation by acting as cellular dewatering protectants under stress conditions. Molecular regulatory networks related to salt stress are complex and have not been fully explored [20]; mining key and novel salt-tolerance-related genes is required for developing breeding strategies to enhance salt stress tolerance in crops
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