硫化氢对盐碱胁迫下裸燕麦光合生理的影响

Effects of hydrogen sulfide on photosynthetic physiology of naked oat under saline-alkali stress

【目的】研究硫化氢(H_(2)S)对盐碱胁迫下裸燕麦光合生理的影响,为揭示H_(2)S增强裸燕麦耐盐碱性机理提供理论依据。【方法】以盆栽砂培裸燕麦品种‘定莜9号’为材料,在抽穗期灌根施用50 mmol/L的盐碱溶液,同时喷施50μmol/L H_(2)S供体硫氢化钠(NaHS)溶液或结合灌根施用1 mmol/L H_(2)S合成抑制剂羟胺(HA),研究H_(2)S对盐碱混合胁迫下裸燕麦叶片叶绿素含量、光合气体交换参数、叶绿素荧光参数、叶黄素循环色素含量和相关基因相对表达量、卡尔文循环关键酶活性及植株生长的影响。【结果】盐碱混合胁迫下,喷施NaHS可显著缓解裸燕麦叶片光合速率(P n)、气孔导度(G s)、蒸腾速率(T r)、气孔限制值(L s)、水分利用效率(WUE)的下降和胞间CO_(2)浓度(C i)的提高;显著提高光化学淬灭系数(q L),紫黄质脱环氧化酶(VDE)和玉米黄质环氧化酶(ZEP)基因相对表达水平以及转酮醇酶(TK)活性;降低紫黄质(V)、单环氧玉米黄质(A)、玉米黄质(Z)含量和叶黄素循环的脱环氧化状态(A+Z)/(V+A+Z)以及1,5-二磷酸核酮糖羧化酶活化酶(RCA)、3-磷酸甘油醛脱氢酶(GAPDH)和景天庚酮糖-1,7-二磷酸酶(SBPase)活性;缓解裸燕麦根系和地上部干质量的下降幅度;而对裸燕麦叶片叶绿素含量、初始荧光(F_(o))、最大荧光(F_(m))、最大光化学量子产量[(F_(m)-F_(o))/F_(m)]、实际光化学量子产量[Y(Ⅱ)]、非光化学淬灭系数(NPQ)、非调节性能量耗散量子产量[Y(NO)]、调节性能量耗散量子产量[Y(NPQ)]和相对电子传递速率(ETR),以及1,5-二磷酸核酮糖羧化酶(Rubisco)和果糖-1,6-二磷酸醛缩酶(FBA)活性无显著影响。增施HA后部分或完全逆转了上述喷施NaHS的作用。【结论】H_(2)S通过加快叶黄素循环运转、提高光系统Ⅱ反应中心开放程度、协调卡尔文循环关键酶活性,缓解盐碱胁迫对裸燕麦光合作用和生长的抑制作用,从而增强裸燕麦耐受盐碱胁迫的能力。

【Objective】This study investigated the effect of hydrogen sulfide(H_(2)S)on photosynthetic physiology of naked oat under saline-alkali stress to provide basis for revealing the mechanism of salt-alkali tolerance enhancement by H_(2)S.【Method】Sand-cultivated naked oat variety‘Dingyou 9’in pots were sprayed with 50μmol/L H_(2)S donor sodium hydrosulfide(NaHS)solution with and without 1 mmol/L H_(2)S synthesis inhibitor hydroxylamine(HA)at heading stage.The effects of H_(2)S on chlorophyll content,photosynthetic gas exchange parameters,chlorophyll fluorescence parameters,key enzyme activities of Calvin cycle in leaves and plant growth of naked oats under 50 mmol/L saline-alkali mixed stress were studied.【Result】Under saline-alkali mixed stress,spraying NaHS significantly alleviated the decrease in photosynthetic rate(P n),stomatal conductance(G s),transpiration rate(T r),stomatal limit value(L s)and water use efficiency(WUE)and the increase of intercellular CO_(2)concentration(C i)in naked oat leaves.It significantly increased photochemical quenching coefficient(q L),relative expression levels of violaxanthin de-epoxidase(VDE)and zeaxanthin epoxidase(ZEP)genes and activity of transketolase(TK),while significantly reduced contents of violaxanthin(V),antheraxanthin(A)and zeaxanthin(Z),de-epoxidation state of xanthin circle(A+Z)/(V+A+Z)and activities of ribulose-1,5-bisphophate carboxylase activase(RCA),glyceraldehyde-3-phosphate dehydrogenase(GAPDH)and sedoheptulose-1,7-bisphosphatase(SBPase).It also mitigated the decline in dry weight of roots and shoots of naked oats,but had no significant effect on chlorophyll content,initial fluorescence(F_(o)),maximum fluorescence(F_(m)),maximum photochemical quantum yield[(F_(m)-F_(o))/F_(m)],actual photochemical quantum yield[Y(Ⅱ)],non-photochemical quenching coefficient(NPQ),unregulated energy dissipation quantum yield[Y(NO)],regulated energy dissipation quantum yield[Y(NPQ)],relative electron transport rate(ETR)and activities of ribulose-1,5-bisphophate carboxylase(Rubisco)and fructose-1,6-bisphosphate aldolase(FBA)in leaves.The addition of HA partially or completely reversed the effects of NaHS spraying.【Conclusion】H_(2)S alleviated the inhibition of photosynthesis and growth of naked oats under saline-alkali stress and enhanced the ability of naked oats to tolerate saline-alkali stress by accelerating xanthophylls cycle,improving opening degree of photosystemⅡreaction center and coordinating activities of key enzymes related to the Calvin cycle.