Transcriptome analysis shows that alkalinity affects metabolism in the roots of Mesembryanthemum crystallinum

Abstract

Mesembryanthemum crystallinum is a model halophyte that switches from C3 photosynthesis to Crassulacean acid metabolism (CAM) upon extreme abiotic stresses. This study aimed to investigate alkalinity-induced root transcriptome profiling in M. crystallinum. M. crystallinum seedlings were treated with 50 mM sodium bicarbonate (NaHCO3; pH 7.5) and 90 mM NaHCO3 (pH 9.5) for 7 d, respectively. Alkalinity-induced differentially expressed genes (DEGs) were identified and annotated. Functional enrichment analysis was performed for DEGs. The expression of genes related to response to stress and CAM were analyzed and compared. Comparing with control, 50 and 90 mM NaHCO3 treatments induced 4 027 and 25 403 DEGs in M. crystallinum roots, respectively. Among these DEGs, 832 and 131 DEGs were consistently upregulated and downregulated by both stresses, respectively. These genes were associated with multiple biological processes related to response to abiotic stresses. Alkaline stress upregulated genes encoding heat shock proteins and ethylene-related genes, but downregulated genes encoding glutathione S-transferases. Also, genes that encode phosphoenolpyruvate carboxylases, phosphoenolpyruvate carboxylase kinase 1, and malate dehydrogenases related to malate accumulation were upregulated by alkalinity. This study indicated that alkaline stress affected the genes related to stress responses, metabolism, and malate accumulation in the roots of M. crystallinum.

Keywords

• alkalinity tolerance
• crassulacean acid metabolism
• degs
• ice plant
• mesembryanthemum crystallinum
• nahco3
• phosphoenolpyruvate carboxylase