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本文以2份甜瓜单基因抗源PI157082和PI482398、聚合基因材料082-398以及‘白皮脆’为试验材料,用3种不同浓度(5×10~5、5×10~7和5×10~9个·mL~(-1))的蔓枯病菌处理,研究并分析在不同浓度蔓枯病病原菌胁迫下甜瓜的抗病表现以及3种内源防御酶苯丙氨酸解氨酶(PAL)、多酚氧化酶(PPO)及过氧化物酶(POD)活性的变化。结果表明:甜瓜蔓枯病菌液浓度为5×10~7个·mL~(-1)时,可以区分聚合基因抗源和单基因抗源对蔓枯病抗性能力的差异,聚合基因抗源在菌液浓度为5×10~9个·mL~(-1)时依然能够抗病。3种防御酶PAL、PPO和POD与甜瓜对蔓枯病的抗性关系非常密切。甜瓜受蔓枯病菌侵染后,防御酶活性比对照明显增高,聚合基因材料酶活性增幅和峰值均高于单基因抗源,单基因抗源活性增幅和峰值均高于感病甜瓜。PAL和PPO在接种后第4~5天活性上升最快,并且在此阶段达到峰值,而POD在中后期仍然保持活性上升的状态。这说明,单一抗性基因的聚合在一定程度上可以提高甜瓜对蔓枯病的抗性,3种防御酶的活性变化可以为鉴定甜瓜蔓枯病早期抗性提供参考。
In this study, two melon monogenic anti-PI157082 and PI482398, polymeric genetic material 082-398 and ’white crisp’ were used as test materials, with three different concentrations (5 × 10-5, 5 × 10-7 and 5 × 10 ~ 9 · mL -1), the disease resistance and the activities of three endogenous defensive enzymes, phenylalanine ammonia lyase (PAL), were studied and analyzed under different concentrations of pathogen, ), Polyphenol oxidase (PPO) and peroxidase (POD) activity. The results showed that when the liquid concentration of V. meliloti was 5 × 10 ~ 7 mL · (-1), the differences in the resistance ability of the polygenic genes and the single gene to vaphal could be distinguished, In the bacteria concentration of 5 × 10 ~ 9 · mL ~ (-1) is still able to fight disease. The three defense enzymes PAL, PPO and POD were closely related to the resistance of melon to the disease. After invaded by M. gossypii, the defensive enzyme activity of melon was significantly higher than that of the control. The increase and the peak value of the enzymatic activity of the polymeric gene were both higher than those of the single gene. The amplitudes and peak values of single gene activity were higher than those of the susceptible melon. The activities of PAL and PPO increased fastest from the 4th to 5th days after inoculation, and peaked at this stage. However, the activity of POD remained unchanged in the middle and later stages. This indicates that the polymerization of a single resistance gene can improve the resistance of melon to vaphal in a certain extent. The changes of the activities of the three kinds of defense enzymes can provide a reference for the identification of the early resistance of melon.