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作 者 ：潘凯,吴凤芝

期 刊 ：生态学报 2007年 27卷 5期 页码：1945~1950

关键词：黄瓜品种；根系分泌物；氨基酸；病情指数；

Keywords:cucumber cultivars, root exudates, amino acid, disease index, correlation,

摘 要 ：以5种对枯萎病不同抗性黄瓜品种为试材，对其根系分泌物氨基酸组分进行测定，并对氨基酸组分与黄瓜品种枯萎病抗病性之间的相关性进行了分析。结果表明：在中抗品种根系分泌中检测到的16种氨基酸：半胱氨酸Cys、苏氨酸Thr、丙氨酸Ala、缬氨酸Val、异亮氨酸Lle、天冬氨酸Asp、亮氨酸Leu、苯丙氨酸Phe、甘氨酸Gly、甲硫氨酸Met、组氨酸His、谷氨酸Glu、酪氨酸Tyr、赖氨酸Lys、丝氨酸Ser和精氨酸Arg。其中的精氨酸在感病品种中没有被检出，组氨酸和精氨酸组分在抗病品种中没有被检出。根系分泌物中总氨基酸含量随品种抗性的增加而降低； 精氨酸、丝氨酸和赖氨酸的含量与品种对枯萎病的病情指数呈负相关，其他13种氨基酸组分含量与品种对枯萎病的病情指数呈正相关，其中苯丙氨酸含量与病情指数呈显著正相关。丝氨酸与苯丙氨酸、天冬氨酸、丙氨酸、甘氨酸的比值均与品种对枯萎病的病情指数呈显著负相关，其中Ser/Phe与品种对枯萎病的病情指数呈极显著负相关。

Abstract:Root exudates have an important effect on the resistance to soil-borne disease in some crops. Free amino acids are important components of some crop root exudates. The cucumber (Cucumis sativus L.) is an economically important vegetable, and fusarium wilt (Fusarium oxysporum. f. sp. cucumerinum owen) infection in cucumber production can be severe. Rigorous investigation of root exudates requires the study of correlations between amino acids components and disease resistance. Therefore, an experiment was designed to investigate this correlation.Root exudates were collected from five cucumber cultivars possesing different fusarium wilt resistance reactions. Free amino acids from these root exudates were then detected using an Automatic Amino Acid Analyzer. Data indicate that the kinds and contents of amino acids examined were different in these root exudates. Sixteen kinds amino acids were detected in root exudates of intermediate-resistant cucumber cultivars (Jinchun 3# and Zhongnong 1101), toindicate aspartic acid, methionine, leucine, glycine, phenylalanine, histidine, arginine, serine, glutamic acid, lysine, tyrosine, cysteine, threonine, alanine, valine, and isoleucine. Arginine was not found in the root exudates of the susceptible cucumber cultivars (Jinyan 4# and Qiupeng), and histidine and arginine were not found in resistant cultivars (Zhongnong 13). The research conclusion moreover, general amino acid content increased with increased degree of susceptibility in these cucumber varieties. Correlations between root exudates and disease indices in these cultivars indicated that disease indices were positively correlated with arginine, serine, and lysine content. However, disease indices were negatively correlated with the contents of the other thirteen amino acids examined. The correlation between phenylalanine content and disease indices was significant (P<0.05) and positive (0.95). A significant (P<0.05) negative relationship was detected between the disease indices and the ratios of content of serine to the asparagines (-0.943), alanine (-0.956), and glycine(-0.902), respectively. The disease indices were highly negatively correlated (P<0.01) with the ratios of content of serine to phenylalanine (-0.959).

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