外源H_2S对NO_3~-胁迫下番茄幼苗生理生化特性的影响

采用营养液水培方法,通过外源施加H2S供体NaHS(100μmol/L),研究了信号分子H2S对100mmol/L NO3-胁迫下番茄幼苗生理生化特性的影响。结果表明:(1)NO3-胁迫下,随着处理时间的延长,番茄幼苗的株高、根长、鲜重和干重显著降低,叶绿素(a、b)含量、净光合速率、气孔导度、蒸腾速率均显著降低,而胞间CO2浓度以及丙二醛(MDA)、H2O2含量增加,超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性显著降低,抗坏血酸(AsA)和还原性谷胱甘肽(GSH)含量显著降低。(2)与NO3-胁迫处理相比,外源NaHS处理1、3、5d后,番茄幼苗的株高、根长、鲜重和干重显著增加,叶绿素(a、b)含量、净光合速率、气孔导度、蒸腾速率均显著升高,而胞间CO2浓度显著降低;MDA和H2O2含量降低,SOD、POD、CAT和APX活性显著增强,AsA和GSH含量显著增加,而且幼苗的硝酸还原酶、谷氨酰胺合成酶、谷氨酸合酶的活性显著增强;L-半胱氨酸脱巯基酶活性和内源H2S含量增加。研究认为,外源H2S可能通过提高抗氧化物酶的活性和增加抗氧化物质含量来缓解NO3-对番茄幼苗造成的伤害,从而增强其对NO3-胁迫耐性。

Effect of Exogenous NaHS on the Physiological and Biochemical Characteristics of Tomato Seedlings under NO3- Stress

The study investigated the effect of gas transmitter H₂S (by adding H₂S donor NaHS) on the physiological and biochemical characteristics of hydroponic growth tomato seedlings under nitrate stress.The result showed that:(1)with the increasing nitrate stress treatment time,the shoot height,root length,fresh weight and dry weight,chlorophyll a and b contents,net photosynthetic rate,gas conductance and transpiration rate decreased significantly,while the intracellular CO₂ concentration,the MDA and H₂O₂ contents increased.The activities of superoxide dismutase,catalase,peroxidase,and ascorbate peroxidase and the antioxidant substances of ascorbate and GSH contents decreased after nitrate stress treatment.(2)When NaHS was added,the shoot height,root length,fresh weight and dry weight,chlorophyll a and b contents,net photosynthetic rate,gas conductance and transpiration rate increased significantly after NaHS added for 1,3,5 days,while the intracellular CO₂ concentration decreased,compared with the nitrate stress treatment alone.The MDA and H₂O₂ contents decreased,while the antioxidant enzyme activities of superoxide dismutase,catalase,peroxidase,and ascorbate peroxidase increased,besides,the antioxidant substances of ascorbate and GSH contents increased after NaHS was added.The activities of nitrate reductase,glutathione synthetase,and glutamate synthase increased after NaHS was added.NaHS treatment stimulated the increase of L-desulfhydrase activity,which in turn induced accumulation of H₂S content.These results indicate that the alleviation of the nitrate stress damage on tomato by H₂S might be fulfilled through increasing the antioxidant enzyme activities and the antioxidant substances contents.