高温下烟草品系0970A花叶病抗性丧失的机理简报

Brief report on the mechanism of mosaic disease resistance loss in tobacco strain 0970A under high temperature

[目的]明确高温(32℃)条件下烟草品系0970A接种TMV后抗性丧失的初步机理。[方法]以烤烟品系0970A(含N基因)为试材,分别设置常温(25℃)接种TMV、常温(25℃)接种无菌水(对照)、高温(32℃)接种TMV、高温(32℃)接种无菌水(对照)共4个处理。接种后0、6、12和24 h,采用qRT-PCR法检测不同处理下烟苗TMV抗性基因(N基因)和抗病相关基因的相对表达量;接种后3 d,比较不同处理下烟苗的TMV抗性表型。[结果]接种TMV后,高温(32℃)培养下烟苗CP基因的相对表达量高于常温(25℃)培养,而N基因的相对表达量则低于常温(25℃)培养。两个培养温度下,RAR1和SGT1基因的相对表达量均随接种时间的推移呈上调趋势,但32℃培养下相对表达量的上升幅度更小;COI1基因的相对表达量均呈下降趋势,且32℃培养下相对表达量的降幅更小。[结论]温度影响烟草N基因和抗病相关基因RAR1、SGT1和COI1的表达,高温(32℃)抑制了TMV诱导相关基因的上调或下调,这可能是高温(32℃)下烟苗TMV抗性丧失的主要原因之一。

[Purpose]To preliminarily clarify the mechanism underlying the loss of resistance to tobacco mosaic virus(TMV)in tobacco line 0970A under high temperature(32℃).[Method]Taking the flue-cured tobacco line 0970A(containing the TMV resistance N gene)as the test material,four treatments were set up:inoculation with sterile water at 25℃,inoculation with TMV at 25℃,inoculation with sterile water at 32℃,and inoculation with TMV at 32℃.At 0,6,12,and 24 h after inoculation,the expression levels of the N gene and other disease resistance-related genes in the tobacco seedlings under different treatments were detected using the qRT-PCR assay.Additionally,the TMV resistance phenotypes of the tobacco seedlings in the different treatment groups were compared 3 days after TMV inoculation.[Result]After TMV inoculation,the level of CP gene expression in tobacco seedlings cultured at high temperature(32℃)was higher than that of the seedlings cultured at normal temperature(25℃),whereas the level of N gene expression was lower at 32℃than at 25℃.At both culture temperatures,the expression levels of the RAR1 and SGT1 genes showed an upward trend,but the increase in expression amplitude at 32℃was smaller.By contrast,the expression level of the COI1 gene showed a downward trend,but the decrease in expression amplitude at 32℃was smaller.[Conclusion]Temperature affects the expression of the tobacco N gene and disease resistance-related genes RAR1,SGT1,and COI1.The results preliminarily infer that high temperature(32℃)inhibits the up-regulation or down-regulation of TMV-inducible genes,which might be one of the main reasons for the loss of resistance to TMV in the tobacco seedlings at high temperature(32℃).