外源一氧化氮对低温胁迫下苦瓜幼苗生长及部分抗逆指标的影响

Effects of exogenous NO on plant growth and resistant characteristics of bitter melon seedlings under low-temperature stress

为探讨外源一氧化氮(NO)提高苦瓜抗冷性的内在机制,以碧绿苦瓜幼苗为试材,对其施加不同浓度(0,0.1,0.5,1.0,1.5和2.0 mmol·L^(-1))的外源NO供体(SNP)并进行低温(8℃)处理,研究外源NO对低温胁迫下苦瓜幼苗的生长、相对电导率、丙二醛(MDA)、脯氨酸含量以及过氧化物酶(POD)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性的影响。结果显示:SNP处理提高了茎粗/株高和叶面积/根体积的比值,降低了苦瓜幼苗叶片相对电导率和MDA含量,提高了叶片脯氨酸含量和SOD,CAT,POD三种酶的活性,从而降低低温胁迫对苦瓜幼苗的伤害。低浓度的SNP处理的苦瓜幼苗抗冷效果好于高浓度的,尤其以0.5 mmol·L^(-1)SNP处理效果最佳。结果表明:低温胁迫下,适宜浓度的外源NO通过提高抗氧化酶活性,促进渗透调节物质的合成,降低膜透性和膜脂过氧化水平,保护了细胞膜结构的稳定性,从而提高苦瓜幼苗抗低温胁迫的能力,促进了苦瓜幼苗的生长。

For exploring the internal mechanism of exogenous NO in improving the cold resistance of bitter melon,in this experiment,the variety of Bilv was taken as test material,different concentrations of sodium nitroprusside（ SNP）（ 0,0. 1,0. 5,1. 0,1. 5 and 2. 0 mmol·L^（-1）） was employed as exogenous nitric oxide（ NO） donor to study the effects of different concentrations of exogenous nitric oxide（ NO） on the plant growth,relative electrical conductivity,MDA content,proline content and the activities of POD,SOD,CAT of bitter melon seedlings under 8 ℃ lowtemperature stress. The results showed that the treatment of SNP could improve plant height/stem diameter and leafarea/root volume; reduce the relative electrical conductivity and content of MDA; increase proline content and the activities of POD,SOD and CAT of the bitter melon seedlings under low-temperature stress to reduce the damage caused by low-temperature. It was also found that the cold resistance effect of treatment with low concentration of SNP was better than that with high concentration,especially the treatment with 0. 5 mmol·L^（-1）SNP was the best. It indicated that the exogenous NO with proper concentration could promote the plant growth and enhance the bitter melon seedlings＇ adaptability for low temperature stress through improving the activities of defensive enzymes,increasing the osmotic adjustment substance contents,reducing membrane lipid peroxidation and protecting the stability of cell membrane structure.