寡糖对干旱胁迫下桔梗的诱导效应研究

Inductive Effect of Oligosaccharide on Platycodon grandiflorum under Drought Stress

为了明确寡糖对干旱胁迫下桔梗抗旱作用的机制,以桔梗为材料,采用桔梗种子萌发水培试验和桔梗幼苗盆栽试验,用0、30、60、120 g/L的PEG-6000模拟干旱胁迫,施加不同质量浓度寡糖(0、5、10、50 mg/L)诱导桔梗,研究寡糖对干旱胁迫下桔梗种子萌发以及桔梗幼苗抗氧化酶活性和MDA含量的影响。结果表明,同一质量浓度的PEG-6000模拟干旱胁迫,在一定质量浓度范围内桔梗种子萌发指标(发芽势、发芽率、发芽指数、根长及芽长)随寡糖质量浓度的增加表现为先增大后减小,寡糖质量浓度为10 mg/L时桔梗种子萌发指标达到最佳。而同一质量浓度寡糖诱导桔梗,PEG-6000溶液浓度越大,桔梗种子萌发所受胁迫越严重。桔梗种子萌发的发芽势、发芽率、发芽指数、根长及芽长之间呈现不同程度正相关。不同质量浓度的寡糖(0、5、10、50 mg/L)分别与30 g/L PEG-6000配施,处理后4~8 d,桔梗幼苗POD和CAT活性、MDA含量均先升高后降低,而SOD活性逐渐升高,寡糖质量浓度为10 mg/L时诱导桔梗幼苗抗旱的效果最佳。POD活性与CAT活性呈现出高度显著正相关(P<0.001),CAT活性与SOD活性呈现出显著正相关(P<0.05),MDA含量分别与POD、CAT、SOD活性呈现出极显著负相关(P<0.01)。

In order to study the drought resistance mechanism of oligosaccharide on Platycodon grandiflo-rum under drought stres s , hydroponic experiments of Platycodon grandiflorum seed germination and pot experiments of Platycodon grandiflorum seedling were co n d uc ted ,in which different concentrations of oli- gosaccharides（0,5,10,50 mg/L） were used to induce Platycodon grandiflorum under the PEG-6000 （ 0 , 30 ,60,120 g/L） simulated drought stress, and the effects of oligosaccharides on seed germination, seed-ling antioxidant enzyme activity and MDA content of Platycodon grandiflorum under drought stress. The results showed that Platycodon grandiflorum seed germination indicators （ germination potential, germina-tion rate, germination index, root length and shoot length） enhanced first and then reduced with the in-crease of oligosaccharides concentration in a certain concentration range, under the same concentration of PEG-6000 simulated drought stress. At 10 mg/L of oligosaccharide Platycodon grandiflorum seed germi-nation was the best. When Platycodon grandiflorum was induced by the same concentration of oligosaccha-ride,when the concentration of PEG-6000 was greater,the stress suffered by Platycodon grandiflorum seed was more serious. Germination potential, germination rate, germination index, root length and shoot length of Platycodon grandiflorum were positively correlated in different degrees. When Platycodon grandiflorum seedlings were induced by different concentrations of oligosaccharides（0,5,10,50 m g / L ） under drought stress of 30 g/L PEG -6000 , after 4-8 d,the activities of P O D and C A T and content of M D A were in-creased at first and then decreased, the activity of S O D were raised gradually in Platycodon grandiflorum seedlings. When Platycodon grandiflorum seedlings were induced by 10 m g / L of oligosaccharide, the drought resistance result w a s the best. T h e activities of P O D and C A T were highly significantly positively correlated（P 〈0. 001 ） . T h e activities of CAT and S O D were significantly positively correlated （ P 〈 0.05）. The content of MDA in Platycodon grandiflorum seedlings was significantly negatively correlated with the activities of POD , CAT , SOD （P 〈0.01）.