外源硫化氢对盐碱胁迫下裸燕麦光合碳代谢的调控

Regulation of exogenous hydrogen sulfide on photosynthetic carbon metabolism in Avena nude under saline-alkaline stress

为探讨外源H_2S对盐碱胁迫下植物光合碳代谢的调控效应,采用盆栽土培实验,以裸燕麦(Avenanuda)为材料,研究喷施50μmol·L^(-1) H2S供体硫氢化钠(Na HS)溶液对3.00 g·kg^(–1)盐碱胁迫下叶片光合和荧光参数,单糖、寡糖和淀粉含量,卡尔文循环和糖代谢关键酶活性及产量构成因素的影响。结果表明:(1)盐碱胁迫下喷施Na HS显著降低裸燕麦叶片叶绿素含量、胞间CO_(2)浓度、光系统Ⅱ(PSⅡ)初始荧光、最大荧光、调节性能量耗散量子产量、光化学荧光淬灭和非光化学淬灭,显著提高Hill反应活力、净光合速率、蒸腾速率、气孔导度、表观CO_(2)利用效率、PSⅡ最大光化学效率和核酮糖1,5-二磷酸羧化酶(Rubisco)、Rubisco活化酶、3-磷酸甘油醛脱氢酶和转酮醇酶活性。说明外源H_2S通过减少光能吸收和降低PSⅡ天线色素吸收光能用于光化学电子传递份额、提高原初光能转化效率和促进水的光解、调控卡尔文循环关键酶活性和增强CO_(2)利用效率缓解盐碱胁迫诱导的光抑制和光合速率下降。(2)盐碱胁迫下喷施Na HS后第7天,裸燕麦叶片α-淀粉酶和蔗糖磷酸合成酶活性显著提高,淀粉、还原糖含量和中性转化酶活性显著降低;第14天,可溶性总糖、还原糖含量和蔗糖合成酶、蔗糖磷酸合成酶活性显著下降,中性转化酶活性显著提高;第7天和第14天葡萄糖、果糖、半乳糖含量不同程度提高,棉子糖含量显著下降,而总淀粉酶、β-淀粉酶、淀粉磷酸化酶、腺苷二磷酸葡萄糖焦磷酸化酶、酸性转化酶活性和岩藻糖、海藻糖、蔗糖含量无显著变化。这表明外源H_2S参与盐碱胁迫下裸燕麦淀粉和蔗糖代谢及多糖和低聚糖之间转化的调控。(3)喷施Na HS对盐碱胁迫下裸燕麦的株高、穗数、穗铃数、千粒质量和生物学产量无显著影响,而穗粒数和籽粒产量显著提高。综上所述,外源H_2S参与盐碱胁迫下裸燕麦光合碳代谢调控,它能够增强裸燕麦对盐碱胁迫的耐性。

Aims The purpose of this study was to investigate the regulatory effect of exogenous H2S on the photosynthetic carbon metabolism of plants under saline-alkali stress.Methods The Avena nude was selected and a potted soil culture experiment was conducted to study the effects of spraying 50µmol·L^(−1) H2S donor sodium hydrosulfide(NaHS)solution on photosynthetic and fluorescence parameters,the contents of monosaccharides,oligosaccharides and starch,the activities of key enzymes in Calvin cycle and sugar metabolism in leaves,and yield components under 3.00 g·kg^(−1) saline-alkali stress.Important findings(1)Spraying NaHS significantly decreased chlorophyll content,intercellular CO_(2) concentration,photosystem II(PSII)initial fluorescence,maximum fluorescence,regulatory energy dissipation,photochemical quenching,non-photochemical quenching,and significantly increased Hill reaction activity,net photosynthetic rate,transpiration rate,stomatal conductance,apparent CO_(2) utility efficiency,PSII maximum photochemical efficiency,and the activities of ribulose-1,5-bisphophate carboxylase(Rubisco),Rubisco activase,glyceraldehyde-3-phosphate dehydrogenase and transketolase in A.nude leaves under salt-alkali stress.These indicated that exogenous H2S could alleviate saline-alkali stress-induced photoinhibition and photosynthetic rate decrease by reducing light energy absorption and the portion of light energy absorbed by the PSII antenna pigment which was used for photochemical electron transfer,improving primary photochemical efficiency and promoting water photolysis of PSII,regulating key enzyme activities in the Calvin cycle,and enhancing CO_(2) utility efficiency.(2)Under saline-alkali stress,the activities ofα-amylase and sucrose phosphate synthase were significantly increased and the contents of starch and reducing sugar and neutral invertase activities were significantly decreased in A.nude leaves on the 7th day after spraying NaHS.On the 14th day,the contents of total soluble sugar and reducing sugar,and the activities of sucrose synthase and sucrose phosphate synthase decreased significantly,and the activity of neutral invertase increased significantly.The contents of glucose,fructose and galactose on the 7th and 14th days increased to varying degrees,and the content of raffinose decreased significantly,while the activities of total amylase,β-amylase,starch phosphorylase,adenosine diphosphate glucose pyrophosphorylase and acid invertase and the contents of fucose,trehalose and sucrose did not change significantly.These changes suggested that exogenous H2S was involved in the regulation of starch and sucrose metabolism and the conversion between polysaccharides and oligosaccharides in A.nude under saline-alkali stress.(3)Spraying NaHS had no significant effect on plant height,spike numbers per plant,boll numbers per spike,thousand-grain weight and biological yield per plant of A.nude under salt-alkali stress,while grain numbers per spike and grain yield per plant were increased significantly.In summary,exogenous H2S participates in the regulation of photosynthetic carbon metabolism in A.nude under salt-alkali stress,and it can enhance the tolerance of A.nude to saline-alkali stress.