外源γ-氨基丁酸对盐碱胁迫下甜瓜种子萌发的影响

Effect of exogenous γ-aminobutyric acid on seeds germination of melon under salinity-alkalinity stress

以盐碱敏感甜瓜(Cucumis melo L.)"一品天下208"种子为材料,研究摩尔浓度50 mmol/L在盐碱胁迫条件下(NaCl、Na_2SO_4、NaHCO_3和Na_2CO_3按摩尔比1∶9∶9∶1),不同外源γ-氨基丁酸(γ-aminobutyric acid,GABA)摩尔浓度0、5、10、50 mmol/L浸种处理对甜瓜种子发芽指标及胚根内抗氧化酶活性和GABA代谢的影响。结果表明:盐碱胁迫显著抑制了甜瓜种子的萌发与胚根和胚芽的生长;不同摩尔浓度GABA浸种处理部分缓解了盐碱胁迫对甜瓜种子萌发的抑制作用。5 mmol/L GABA浸种处理能显著增加胚根内超氧化物歧化酶(superoxide dismutase,SOD)活性;10 mmol/L GABA浸种处理能显著提高可溶性蛋白质含量及内源GABA含量和谷氨酸脱羧酶(glutamate decarboxylase,GAD)活性;50 mmol/L GABA浸种处理能显著提高种子的发芽率、发芽势、活力指数、总鲜质量、胚根和胚芽长,并且能提高过氧化物酶(peroxidase,POD)、过氧化氢酶(catalase,CAT)和GABA转氨酶(GABA transaminase,GABA-T)活性,且显著降低丙二醛(malondialdehyde,MDA)含量。不同摩尔浓度GABA浸种处理效果有差别,但总体而言50 mmol/L GABA浸种有利于缓解盐碱胁迫对甜瓜种子萌发的抑制作用,提高甜瓜种子耐盐碱能力。

Due to the salinity-alkalinity stresses in agricultural environment, the production, quality and economic benefit of crops are seriously restricted. Salinity-alkalinity stresses not only decreased crop yields and affected crop quality, but also severely restricted sustainable and efficient crop production development. Therefore, it is of great significance to increase the crop resistance to salinity-alkalinity stresses for high-efficient and high-yield agriculture. γ-aminobutyric acid （GABA） is a non protein amino acid, commonly exist in plant and animal tissues, which can indirectly affect plant growth and development under stress. However, there are few studies about the effect of exogenous GABA on seed germination under salinity-alkalinity stress. Thus, the experiment was carried out to screen the optimal concentration of GABA to improve the salt resistance of melon seeds. Salt sensitive variety of melon （Cucumis melo L. ） seeds （cv ＂Yipintianxia 208＂）, which is sensitive to salinity alkalinity stresses, was chosen as experiment material. The effects of different concentrations （0, 5, 10, and 50 mmol/L） of exogenous GABA on germination index, radicle antioxidant enzyme activities, and GABA metabolism of melon seeds under 50 mmol/L salinity-alkalinity stress conditions （NaCI： Na2 SO4 ： NaHCO3 ：Na2 CO3 as molar volume ratio 1：9：9：1） were studied. There were five treatments in this experiment （i） CK： purified water presoaking and pre-germination; （ii） T1 ： purified water presoaking and pre-germination under 50 mmol/L salinity- alkalinity stress; （iii） T2：5 mmol/L GABA presoaking and pre-germination under 50 mmol/L salinity alkalinity stress; （iv） Td： 10 mmol/L GABA presoaking and pre-germination under 50 mmol/L salinity-alkalinity stress; （v） T4：50 mmol/L GABA presoaking and pre-germination under 50 mmol/L salinity-alkalinity stress. The results showed that salinity-alkalinity stresses significantly inhibited seeds germination and the growth of radicles and embryos of melon. Soaking seeds in different concentrations of GABA partly decreased the stress-induced inhibition on seeds germination of melon. Compared with the melon seeds in the treatment of salinity-alkalinity stress without GABA, a presoaking concentration of 5 mmol/L GABA improved superoxide dismutase （SOD） activity, and presoaking with 10 mmol/L GABA improved soluble protein content, endogenous GABA content and glutamate decarboxylase （GAD） activity in the radicles; presoaking with 50 mmol/L GABA improved seed germination rates, germination potential, vigor index, fresh mass, lengths of radicles and embryos, and peroxidase （POD）, catalase （CAT） and GABA t activities and decreased malondialdehyde （MDA） content. （GABA-T） It was concluded that 50 mmol/L GABA presoaking significantly alleviate the inhibition of melon seeds under salinity-alkalinity stress, and improved the salt tolerance of melon seeds.