酸碱度对稻瘟病菌BAS4过表达菌株耐受性的影响

目的]探明酸碱度(pH)对稻瘟病活体寄生相关分泌蛋白BAS4(Biotrophy-associated secreted protein 4)过表达菌株形态发育及受侵染水稻防御相关基因表达的影响,揭示pH对稻瘟病菌效应蛋白在稻瘟病菌与水稻互作中的作用机制,为农业生产上预测预报不良环境因子对水稻生产的影响提供参考.方法]利用不同pH(5.00、6.00、7.00和8.00)处理稻瘟病菌过表达菌株35S:BAS4/Mo-1和野生型菌株A1343R-7,比较分析不同pH对过表达菌株菌落生长、产孢量、孢子萌发率、菌丝干重和附着胞形成等形态发育的影响.调查pH 5.00和pH 8.00预处理过表达菌株再侵染水稻的发病率,采用实时荧光定量PCR(qRT-PCR)分析受侵染水稻防御相关基因的表达情况.结果]不同pH对BAS4过表达菌株菌落生长、产孢量、萌发率、菌丝干重和附着胞形成的影响较pH对野生型菌株小,pH 5.00和pH 8.00处理的BAS4过表达菌株均提高了其侵染水稻的发病率.pH 5.00和pH 8.00抑制其处理的BAS4过表达菌株侵染水稻病程相关基因、SA-途径、JA-途径相关基因及PR5的表达,诱导HSP90在侵染水稻早期上调表达.结论]pH可影响BAS4过表达菌株的形态发育,但其处理的过表达菌株侵染水稻的大部分防御相关基因表达下调,预示BAS4过表达菌株对pH具有较强的耐受性.

Effects of pH on tolerance of Magnaporthe oryzae BAS4 overexpressed strain

Objective]This study investigated the effects of pH on morphological development of biotrophy-associa-ted secreted protein 4(BAS4)overexpressed strain and expression of defense-related genes in infected rice ,and disco-vered the mechanism of pH on rice blast effect protein in the interaction of rice blast strain and rice,in order to provide important reference for predicting effects of adverse environmental factors on rice planting in agricultural production.Method]Overexpressed strain of Magnaporthe oryzae(35S:BAS4/Mo-1)and wild strain A1343R-7(WT)were pre-treated with different pH values(pH 5.00,pH 6.00,pH 7.00,and pH 8.00) to analyze the effects of pH on colony growth,spore quantity,spore germination rate,dry weight of hypha,and appressorium formation of overexpressed strain. And the disease incidence of overexpressed strain re-infected rice which were pre-treated with pH5.0 and pH8.0 was investigated and the expression of infected rice defense-related genes was analyzed by real-time fluorescent quantita-tive PCR(qRT-PCR).Result]The result showed that the effect of pH on colony growth,spore quantity,dry weight of hypha,germination rate and appressorium formation of 35S:BAS4/Mo-1 was smaller than the effect on those of wild-type strain. Disease incidence of rice infected by overexpressed strains which were pre-treated with pH 5.00 and pH 8.00was increased. pH 5.00 and pH 8.00 repressed the expression of pathogenesis-related genes,SA-pathway genes,JA-path-way genes and PR5 of overexpressed strain that infected rice,while up-regulated the expression of HSP90 in the early stage of infection in rice.Conclusion]Although morphologic development of BAS4 overexpressed strains are influenced by pH,the expression of most rice denfense-related genes pre-treated with pH appears down-regulation,which indicates that BAS4 overexpressed strains have strong tolerance to pH.