Effects of foliar-spraying nitric oxide on the carbon metabolism enzymes activities and nutrients in leaves and roots of Reaumuria soongorica (pall.) maxim seedlings under NaCl stress

Abstract

Salinity affects the growth of Reaumuria soongorica. Nitric oxide (NO) is a plant signaling molecule that can improve the stress resistance of R. soongorica. To date, studies on the salt tolerance of R. soongorica have mainly focused on its physiological and biochemical indexes. While the useful role of NO in plant response to salt stress and the molecular mechanisms of carbon metabolism in R. soongorica have scarcely been reported. Therefore, sodium nitroprusside (SNP) as NO donor (0, 0.01, 0.10, 0.25, 0.50, 1.0 mmol L−1) was used to determine the effects of NaCl stress on carbon metabolism and salt resistance in R. soongorica. Principal component and membership function analysis were used to select the best carbon metabolism indexes, optimal SNP concentration, and their ability to alleviate NaCl stress. The results showed that 300 mmol L−1 NaCl alone inhibited carbon metabolism and SNP promoted the adaptation of R. soongorica to NaCl stress. The accumulation of total soluble sugar, sucrose, starch, and the activities of sucrose phosphate synthase (SPS) and sucrose synthase (SS) in leaves and roots decreased significantly. The SNP foliar spray significantly increased the content of total soluble sugar and sucrose in roots and leaves and the activities of SS, SPS, acid invertase (AI) and neutral invertase (NI) in leaves but decreased the activities of SS, AI and NI in roots. These results suggested that the best treatment for alleviating NaCl stress was 0.10 mmol L−1 SNP and that the ability to alleviate NaCl stress in R. soongorica could be evaluated based on the activities of soluble sugar, sucrose, NI, and total invertase (TI). This study provides a theoretical basis for the protection and utilization of R. soongorica under saline conditions and also provides a foundation for further research.