Involvement of cell cycle and ion transferring in the salt stress responses of alfalfa varieties at different development stages

Genome-Wide Identification of the GPAT Family in Medicago sativa L. and Expression Profiling Under Abiotic Stress

Glycerol-3-phosphate acyltransferase (GPAT), as a rate-limiting enzyme engaged in lipid synthesis pathways, exerts an important role in plant growth and development as well as environmental adaptation throughout diverse growth stages. Alfalfa (Medicago sativa L.) is one of the most significant leguminous forages globally; however, its growth process is frequently exposed to environmental stress, giving rise to issues such as impeded growth and decreased yield. At present, the comprehension of the GPAT genes in alfalfa and their reactions to abiotic stresses is conspicuously deficient. This study identified 15 GPATs from the genome of "Zhongmu No. 1" alfalfa, which were phylogenetically categorized into three major groups (Groups I ~ III). Furthermore, Group III is further subdivided into three distinct subgroups. MsGPATs belonging to the same subfamily exhibited similar protein conserved motifs and gene structural characteristics, in which groups with simple conserved motifs had more complex gene structures. A multitude of regulatory cis-elements pertinent to hormones and responses to environmental stress were detected in their promoter regions. In addition, a spatial-temporal expression analysis showed that MsGPATs have significant tissue specificity. Furthermore, the transcriptomic analysis of ABA treatment and the qRT-PCR results under drought, salt, and cold stress demonstrated that the majority of MsGPATs respond to abiotic stress with pronounced timely characteristics. It was also ascertained that these GPAT genes might assume a crucial role in salt and drought stress. This research can further constitute a fundamental basis for the exploration of the alfalfa GPAT family, the screening of key GPATs, and the investigation of their functionalities.

NO enhances the adaptability to high-salt environments by regulating osmotic balance, antioxidant defense, and ion homeostasis in eelgrass based on transcriptome and metabolome analysis

Introduction

Eelgrass is a typical marine angiosperm that exhibits strong adaptability to high-salt environments. Previous studies have shown that various growth and physiological indicators were significantly affected after the nitrate reductase (NR) pathway for nitric oxide (NO) synthesis in eelgrass was blocked.

Methods

To analyze the molecular mechanism of NO on the adaptability to high-salt environment in eelgrass, we treated eelgrass with artificial seawater (control group) and artificial seawater with 1 mM/L Na2WO4 (experimental group). Based on transcriptomics and metabolomics, we explored the molecular mechanism of NO affecting the salt tolerance of eelgrass.

Results

We obtained 326, 368, and 859 differentially expressed genes (DEGs) by transcriptome sequencing in eelgrass roots, stems, and leaves, respectively. Meanwhile, we obtained 63, 52, and 36 differentially accumulated metabolites (DAMs) by metabolomics in roots, stems, and leaves, respectively. Finally, through the combined analysis of transcriptome and metabolome, we found that the NO regulatory mechanism of roots and leaves of eelgrass is similar to that of terrestrial plants, while the regulatory mechanism of stems has similar and unique features.

Discussion

NO in eelgrass roots regulates osmotic balance and antioxidant defense by affecting genes in transmembrane transport and jasmonic acid-related pathways to improve the adaptability of eelgrass to high-salt environments. NO in eelgrass leaves regulates the downstream antioxidant defense system by affecting the signal transduction of plant hormones. NO in the stems of eelgrass regulates ion homeostasis by affecting genes related to ion homeostasis to enhance the adaptability of eelgrass to high-salt environments. Differently, after the NO synthesis was inhibited, the glyoxylate and dicarboxylate metabolism, as well as the tricarboxylic acid (TCA) cycle, was regulated by glucose metabolism as a complementary effect to cope with the high-salt environment in the stems of eelgrass. These are studies on the regulatory mechanism of NO in eelgrass, providing a theoretical basis for the study of the salt tolerance mechanism of marine plants and the improvement of terrestrial crop traits. The key genes discovered in this study can be applied to increase salt tolerance in terrestrial crops through cloning and molecular breeding methods in the future.