Effect Of Exogenous Hydrogen Sulfide On The Growth And Uptake And Transportation Of Na~+of Wheat Seedlings Under Salt Stress

Salt stress affects the growth and development of crops and plants heavily.Hydrogen sulfide （H₂S） is the third gaseous signaling molecule after nitric oxide （NO）and carbon monoxide （CO） and has similar functions with them in animals. It is justthe beginning about the physiological function in plants and the response of plants tostress of H₂S. So the function of H₂S in plants should be further investigated. In thepresent study, the effects of exogenous hydrogen sulfide on the growth of seedlingsand the absorption and transportation of Na⁺of LM15 （Triticum aestivum cv） undersalt stress were investigated. The main results are as follows:1. Seed priming with exogenous H₂S donor NaHS markedly alleviated theinhibition of seed germination and oxidative damage of wheat induced by salt stress.The seed germination rate, germination index, vigor index and the activity of catalase（CAT）, peroxidase （POD）, superoxidedismutase （SOD）, acorbateperoxidase （APX）,α-amylase andβ-amylase under 100 mmol/L NaCl treatment were reduced to 68.33%,57.43%, 23.53%, 55.55%, 75.21%, 73.4%, 49.53%, 58.98%, 60.13% respectively,compared to control. However, under the same salt stress, 0.05 mmol/L NaHS led toreduction of the above parameters only to 93.1%, 70.78%, 45.48%, 66.67%, 86.46%,86.32%, 74.6%, 70.09%, 73.68% respectively, compared to control. Also, under saltstress, malondialdehyde （MDA） in the seedlings treated with 0.05mM NaHS wassignificantly less than control. So, seed priming with 0.05 mmol/L NaHS couldsignificantly alleviated inhibition of the seed germination rate, germination index,vigor index and the activity of catalase （CAT）, peroxidase （POD）,superoxidedismutase （SOD）, acorbateperoxidase （APX）,α-amylase andβ-amylase ofwheat under 100 mmol/L NaCl stress, which caused less oxidative damage.2. Seed priming with exogenous H₂S donor NaHS markedly alleviated theinhibition of wheat seedlings growth and Na⁺accumualtion induced by salt stress. Inthe present study, the effect of seed priming with exogenous H₂S donor NaHS on thegrowth of seedlings, the content of Na⁺and K⁺and the ratio of Na⁺/K⁺of LM15 undersalt stress were investigated. The fresh and dry weight of LM15 under 100 mmol/LNaCl treatment were reduced to 64.66%, 60.19% respectively, compared to control. However, under the same salt stress, 0.05 mmol/L NaHS led to reduction of the aboveparameters only to 76.44%, 72.93% respectively, compared to control. Therefore, seedpriming with 0.05 mmol/L NaHS could significantly alleviate the growth of wheat，under 100 mmol/L NaCl stress. Under salt stress, 0.05 mmol/L NaHS pretreatmentmade the Na⁺content and Na⁺/K⁺ratio of wheat seedlings decrease by 25.36%,29.91% respectively, compared to 100 mmol/L NaCl treatment. But the K⁺contentwas not affected. These results suggeted that hydrogen sulfide significantly alleviatedthe growth reduction of wheat seedlings caused by salt stress possibly via decreasingthe Na⁺content.3. Seed priming with exogenous H₂S donor NaHS markedly decreased Na⁺uptake and transport to the shoot and icreased Na⁺export of wheat seedlings undersalt stress. In this study, the effect of seed priming with exogenous H₂S donor NaHSon the uptake and transportation of wheat seedlings under salt stress were investigated.The value of SA of the 0.05 mmol/L NaHS pretreatment increased by 13.77%,compared to only NaCl treatment, but the value of ST （shoot/root） decreased by11.92%. It indicated that Na⁺export of roots under 0.05 mmol/L NaHS pretreatment isstronger than under only 100 mmol/L NaCl stress, but Na⁺transportation to the shootsis less. Amiloride （the inhibitor of SOS1）, Ca2+（the inhibitor of NSCCs）, Ba2+（theinhibitor of high affinity K⁺transporter）, TEA+（the inhibitor of low affinity K⁺transporter） were used to study how H₂S alleviates the inhibition of LM15 under saltstress. The Na⁺content of wheat seedlings of 0.05 mmol/L NaHS pretreatmentdecreased by 15.32%, compared to 100 mmol/L NaCl stress. However, the Na⁺content of the seedlings treated with 0.05 mmol/L NaHS and 0.1 mmol/L amiloride isidentical with only 100 mmol/L NaCl stress. The results suggested that exogenousH₂S could decrease the Na⁺content of the wheat seedlings by acting on SOS1. TheNa⁺content of wheat seedlings of 0.05 mmol/L NaHS treatment, 0.05 mmol/L NaHSand 20 mmol/L CaCl2treatment decreased by 9.20%, 22.61% compared to 100mmol/L NaCl stress. The results suggested that exogenous H₂S could not decrease theNa⁺content of the wheat seedlings by acting on NSCCs. The Na⁺content of wheatseedlings of 0.05 mmol/L NaHS treatment, 0.05 mmol/L NaHS and 5 mmol/L BaCl2treatment decreased by 32.41%, 9.44% compared to 100 mmol/L NaCl stress. TheNa⁺content of wheat seedlings of 0.05 mmol/L NaHS treatment, 0.05 mmol/L NaHSand 10mmol/L TEA+treatment decreased by 6.97%, 11.73% compared to 100 mmol/L NaCl stress. So, the results suggested that exogenous H₂S could decrease theNa⁺content of the wheat seedlings by acting on high affinity K⁺transporter （HKT、KUP/HAK）, while not by acting on low affinity K⁺transporter.