Physiological and Molecular Features of Puccinellia tenuiflora Tolerating Salt and Alkaline‐Salt Stress

Abstract Saline‐alkali soil seriously threatens agriculture productivity; therefore, understanding the mechanism of plant tolerance to alkaline‐salt stress has become a major challenge. Halophytic Puccinellia tenuiflora can tolerate salt and alkaline‐salt stress, and is thus an ideal plant for studying this tolerance mechanism. In this study, we examined the salt and alkaline‐salt stress tolerance of P. tenuiflora , and analyzed gene expression profiles under these stresses. Physiological experiments revealed that P. tenuiflora can grow normally with maximum stress under 600 mmol/L NaCl and 150 mmol/L Na 2 CO 3 (pH 11.0) for 6 d. We identified 4,982 unigenes closely homologous to rice and barley. Furthermore, 1,105 genes showed differentially expressed profiles under salt and alkaline‐salt treatments. Differentially expressed genes were overrepresented in functions of photosynthesis, oxidation reduction, signal transduction, and transcription regulation. Almost all genes downregulated under salt and alkaline‐salt stress were related to cell structure, photosynthesis, and protein synthesis. Comparing with salt stress, alkaline‐salt stress triggered more differentially expressed genes and significantly upregulated genes related to H + transport and citric acid synthesis. These data indicate common and diverse features of salt and alkaline‐salt stress tolerance, and give novel insights into the molecular and physiological mechanisms of plant salt and alkaline‐salt tolerance.