不同浓度氯化钙浸种处理对水稻防御酶活性和抗褐飞虱的影响

Effects of seed soaking with different concentrations of calcium chloride on rice defense enzyme activities and resistance to Nilaparvata lugens(Hemiptera:Delphacidae)

【目的】研究不同浓度氯化钙(calcium chloride,CaCl_(2))浸种处理对水稻防御酶活性和抗褐飞虱Nilaparvata lugens的影响。【方法】分别用10,20,30,40和50 mmol/L CaCl_(2)溶液浸泡水稻种子48 h,以蒸馏水浸种为对照,待水稻长至分蘖期时,检测褐飞虱3龄若虫取食胁迫下各浓度CaCl_(2)浸种处理水稻植株叶鞘苯丙氨酸解氨酶(phenylalanine ammonia lyase,PAL)、过氧化物酶(peroxidase,POD)、多酚氧化酶(polyphenol oxidase,PPO)和β-1,3-葡聚糖酶(β-1,3 glucanase,β-1,3-GA)活性,以及褐飞虱2龄若虫取食不同浓度CaCl_(2)浸种处理水稻植株以及1 mmol/L钙离子螯合剂乙二醇四乙酸(ethylene glycol tetraacetic acid,EGTA)和离子通道抑制剂氯化镧(lanthanum chloride,LaCl_(3))分别与20 mmol/L CaCl_(2)同时浸种处理植株7 d后的存活率。【结果】没有褐飞虱取食的情况下,各浓度CaCl_(2)浸种处理的水稻其叶鞘PAL,POD,PPO和β-1,3-GA酶活性与对照相比无显著差异;褐飞虱3龄若虫取食胁迫下,CaCl_(2)浸种处理的水稻植株以及对照植株叶鞘中以上4种防御酶的活性都显著升高,其中CaCl_(2)浸种处理水稻中的升高幅度大于对照水稻中的升高幅度,褐飞虱取食时不同浓度CaCl_(2)浸种对水稻植株叶鞘中各防御酶活性的影响不同,其中30 mmol/L CaCl_(2)浸种处理中PAL,POD和PPO酶活性分别比对照高104.88%,94.32%和61.84%;10和20 mmol/L CaCl_(2)浸种处理中β-1,3-GA活性分别比对照高27.75%和33.04%。褐飞虱2龄若虫取食10,20和30 mmol/L CaCl_(2)浸种处理的植株7 d后,存活率比取食对照植株的分别低32.68%,22.54%和30.28%,但取食40和50 mmol/L CaCl_(2)浸种处理植株的褐飞虱若虫,其存活率与取食对照植株的相比无显著差异。此外,1 mmol/L钙离子螯合剂EGTA和离子通道抑制剂LaCl_(3)分别与20 mmol/L CaCl_(2)同时浸种处理水稻显著抑制20 mmol/L CaCl_(2)诱导的水稻对褐飞虱抗性的影响,取食EGTA+CaCl_(2)和LaCl_(3)+CaCl_(2)浸种处理水稻的褐飞虱若虫,其存活率分别比取食CaCl_(2)浸种处理的高25.80%和22.12%。【结论】通过浸种方式对水稻进行外源钙处理,可以使水稻植株进入防御警备状态,当其遭受褐飞虱取食为害时,会产生更高的防御酶活性,增强水稻对褐飞虱的抗性。

【Aim】To investigate the effects of seed soaking with different concentrations of calcium chloride(CaCl_(2))on rice defense enzyme activities and resistance to the brown planthoppers(BPH),Nilaparvata lugens.【Methods】Rice seeds were respectively soaked in 10,20,30,40 and 50 mmol/L CaCl_(2) solution for 48 h,and the control seeds were soaked in distilled water.At the tillering stage,the activities of phenylalanine ammonia lyase(PAL),peroxidase(POD),polyphenol oxidase(PPO)andβ-1,3-glucanase(β-1,3-GA)in leaf sheaths of rice plants pretreated by soaking seeds in various concentrations of CaCl_(2) with or without infestation by the 3rd instar nymphs of BPH were tested,and the survival rates of the 2nd instar nymphs of BPH fed on rice plants subjected to seed soaking treatment with different concentrations of CaCl_(2),calcium chelator ethylene glycol tetraacetic acid(EGTA)(1 mmol/L)plus 20 mmol/L CaCl_(2) and ion channel inhibitor lanthanum chloride(LaCl_(3))(1 mmol/L)plus 20 mmol/L CaCl_(2),respectively,for 7 d were examined as well.【Results】Without BPH infestation,the activities of PAL,POD,PPO andβ-1,3-GA in rice leaf sheaths in seed soaking treatments with various concentrations of CaCl_(2) showed no significant differences from those of the control.When the rice plants were infested by the 3rd instar nymphs of BPH,the activities of these four defense enzymes in leaf sheaths of CaCl_(2)-pretreated rice plants and the control rice plants all increased significantly,while the ascending degrees of all enzyme activities in CaCl_(2)-pretreated rice plants were higher than those in the control plants.The effects of seed soaking with different concentrations of CaCl_(2) on the activities of various enzymes in leaf sheaths of rice plants under BPH infestation were different,the activities of PAL,POD and PPO in seed soaking treatment with 30 mmol/L CaCl_(2) were 104.88%,94.32%and 61.84%higher than those in their respective controls,respectively,and theβ-1,3-GA activities in seed soaking treatment with 10 and 20 mmol/L CaCl_(2) were 27.75%and 33.04%higher than those in their respective controls,respectively.After 7 d,the survival rates of the 2nd instar nymphs of BPH fed on the rice plants subjected to seed soaking treatment with 10,20 and 30 mmol/L CaCl_(2) were 32.68%,22.54%and 30.28%lower than that fed on the control plants,respectively,but the survival rates of BPH nymphs fed on the plants subjected to seed soaking treatment with 40 and 50 mmol/L CaCl_(2) showed no significant differences from that fed on the control plants.Additionally,calcium chelator EGTA(1 mmol/L)and ion channel inhibitor LaCl_(3)(1 mmol/L)significantly inhibited the effects of CaCl_(2)(20 mmol/L)on induced resistance in rice plants to BPH,and the survival rates of nymphs fed on rice plants subjected to seed soaking treatment with EGTA+CaCl_(2) and LaCl_(3)+CaCl_(2) were 25.80%and 22.12%higher than that fed on rice plants subjected to seed soaking treatment with CaCl_(2),respectively.【Conclusion】Seed soaking treatment with CaCl_(2) can prime rice plants in a stage of preparing for defense,resulting in higher enzyme activities when attacked by BPH,and thus increasing rice resistance against BPH.