Research Of BrREMORIN In Growth And Development And Saline-alkali Stress In Tobacco

REMORIN（REM）is a plant-specific protein family,located in the plasma membrane,is an important component of lipid rafts,and plays important functions in plant growth and development,hormone signal transduction and abiotic stress.Saline-alkali stress is an important abiotic stress that restricts plant growth and development,so it is very important to solve land salinization and how to effectively utilize saline-alkali land resources.In this study,transgenic tobacco of overexpressing BrREMORIN gene was used as the research material to evaluate its growth,development and saline-alkali tolerance.RNA-seq analysis revealed the regulation mechanism of REMORIN protein respond to saline-alkali stress in plants.The research results are as follows:（1）Tobacco plants of overexpressing the BrREM6.5 gene were obtained,and quantitative expression showed that the expression level of this gene in flowers was higher than in leaves.（2）Overexpression of BrREM1.2 gene promoted the increase of tobacco leaf number,root length,plant height and 100-grain weight and branching,and decreased seed setting rates;while overexpression of BrREM1.4 gene had no significant effect on plant height;overexpression of BrREM6.5 The gene promotes the increase of leaf number and root length and branching,and the decrease of 100-grain weight and seed setting rate.The results indicated that the BrREMORIN gene was involved in the regulation of plant growth and development.（3）After salt and alkali stress treatments,the germination energy and germination rate of tobacco seeds of overexpressing BrREM1.2 and BrREM1.4 genes,the root length and plant height of seedlings were significantly increased,and the MDA content in the aerial parts of the plants was significantly decreased.Improve the salt and alkali tolerance of plants.The MDA content in the aerial part of tobacco plants overexpressing BrREM6.5 was decreased after salt and alkali treatment,and the root length and plant height were increased after alkali stress,but there was no significant difference under salt stress.The expression levels of stress-responsive genes Nt POD,Nt CAT and Nt Rd29B were significantly up-regulated in BrREM1.2-OE2 tobacco plants.（4）BrREM1.2-OE2 tobacco plants had differentially expressed genes in the three comparison groups after Na Cl treatment:4 h VS 0 h,3774,8 h VS 0 h,3906,8 h VS 4 h,3178,these DEGs were significantly enriched in terpenoid and polyketide metabolism,lipid metabolism,glycan biosynthesis and metabolic pathways.The three comparison groups after Na HCO₃ treatment had differentially expressed genes 4 h VS 0 h,4065,8 h VS 0 h,2252,8 h VS 4 h,1719,DEGs were enriched by KEGG,and the energy metabolism,metabolism of terpenoids and polyketides,metabolism of other amino acids,and biosynthetic metabolic pathways of other secondary metabolites were significantly enriched.Under saline-alkali stress,the expression levels of CYP450 and terpene synthase genes related to terpenoid synthesis were significantly up-regulated,and the expression levels of CER1 gene related to wax synthesis and chlorophyll a-b binding protein related to photosynthesis were significantly down-regulated.This indicated that the BrREMORIN1.2 gene may respond to saline-alkali stress by regulating the synthesis of terpenes,waxes and photosynthesis.