Study On Molecular Mechanism Of Salt Gland Secretion And Salt Tolerance In Rare Recretohalophyte Reaumuria Trigyna

Reaumuria trigyna?Reaumuria genus,family Tamarieaceae?is an ancient and relict plant of Tethys ocean origin.It is endemic to the arid and semi-arid regions of Eastern Alxa-West Ordos area.The species has a strong adaptability to saline environments because of its unique salt gland structure.Salt glands are regarded as special epidermal cells owing to their capability to excrete excess salt from the plant.In this study,gene-chip technology was used to screen the salt secretion-related genes.The Non-Invasive Micro-test Technique?NMT?was used to determine the Na⁺,K⁺,and H⁺secretion rate of salt gland in Reaumuria trigyna processed by different inhibitors,the ion-selectivity and influencing factors of salt secretion in salt glands were analyzed systematically;The effects of NO and Ca²⁺on salt gland secretion and salt tolerance of plant were investigated by measuring the physiological and biochemical indices of Reaumuria trigyna.The main results are as follows:1.According to the results of the gene-chip,among the 2776 genes,131 genes were differentially expressed,of which 51 genes were up-regulated and 80 genes were down-regulated.Among these differentially expressed genes,there were 13vesicular transport-related genes,18 ion transport-related genes,23 genes related to metabolism,and the rest are transcription factor-related genes.2.By measuring the ion-secretion rates of salt-stressed Reaumuria trigyna leaves with four inhibitors treatment,including vesicular transport inhibitor BFA,H⁺-ATPase inhibitor Vanadate,Na⁺/H⁺antiporter inhibitor Amiloride and Na⁺:K⁺:Cl^-cotransporter inhibitor Bumetanide,we found that all the inhibitors can significantly reduce the secreteion of Na⁺,K⁺,and H⁺from the individual salt glands in Reaumuria trigyna.3.Datas showed that the secretion of Na⁺and K⁺of the salt glands was significantly increased with Treatment with 0.1 mM SNP?NO donor?or 10 mM CaCl₂.In addition,the fresh weight,chlorophyll,MDA,H₂O₂,PRO,GSH and ASA contents and the enzyme activities of SOD,CAT,POD,APX and ACP under SNP or CaCl₂ treatment were significantly higher than those of the control and salt treatment groups.NO and Ca²⁺could promote salt secretion of individual salt glands and antioxidant activity to a certain extent,decrease the accumulation of harmful substances,quickly remove active oxygen,reduce the degree of cell membrane damage,and ultimately enhance the viability of plants in saline environments.4.The effects of NO and Ca²⁺on stress resistance and the expression of salt gland secretion-related genes of Reaumuria trigyna were investigated by qRT-PCR.The results showed that under SNP and CaCl₂ treatments,to the ion transport-related genes Rt SOS1,RtHKT1,RtKUP11 and RtKCO,the vesicular trafficking-related genes Ug11861?VAMP?and Ug12061?VAMP722?and the antioxidant-related genes RtAPX,Rt GRX,and RtSOD genes expression levels were significantly upregulated compared to salt stress treatment,speculated that the NO and Ca²⁺improve salt glands secreting and resistance ability to salt stress in Reaumuria trigyna through regulating the genes expression.