赤星病抗源的抗性比较

国外赤星病抗源Ｂｅｉｎｈａｒｔ１０００－１和国内抗病品种净叶黄及许金４号的抗病性分属两种不同的类型。本文对７个赤星病抗感程度不同的烟草品种的抗病性分别进行了以下测定：１．通过观察病斑数量和病斑大小测定抗侵入和抗扩展能力；２．测定各品种对两种Ａｌｔｅｒｎａｒｉａ毒素、ＡＴ毒素和细交链格孢酮酸（ＴＡ）处理的反应；３．双列杂交法分析抗性遗传规律。重点对Ｂｅｉｎ－ｈａｒｔ１０００－１和净叶黄的抗性特点进行比较。结果表明：供试品种的抗性特点差异显著，为多基因控制的水平抗性。Ｂｅｉｎｈａｒｔ１０００－１的抗病性是由显性基因控制的，主要表现为抗侵入，病斑数少，但病斑面积却显著大于净叶黄和许金４号。国内抗病品种抗扩展的能力强，同时也较抗侵入，它们的抗性基因大部分是隐性的。各品种对ＡＴ毒素和ＴＡ的敏感程度分别与其抗病菌侵入和抗病斑扩展的能力高度相关。文中还就真菌毒素在致病过程中的作用以及它们在赤星病抗性研究中的应用做了讨论。同时，就不同抗性类型的抗源在烟草抗病育种中应用的可能性进行了分析

Comparison of resistance in various brown spot resistant varieties

Two distinct types resistant to brown spot were found in Beinhart1000 1 and in Chinese resistant varieties Jingyehuang and Xujin the Fourth.The resistance of 7 tobacco varieties different in the disease tolerance as determined these were:a)Resistance to invasion and spreading by Alternaria alternata (Fries)Keissler revealed by the number and size of lesions;b)Reaction of varieties to pathogen produced AT toxin and tenuazonic acid;c)Hereditary features by diallel cross analysis.Comparison of the resistance bearing varieties was based on these determinations.The results showed significant variation of the stated characteristics among the varieties.Brown spot resistance of the selected varieties was found horizontal and polygenic.The Beinhart1000 1 resistance was controlled by dominant genes,expressed as resistance to invasion with fewer lesions,but the average size of the lesions was large.On the other hand,resistant genes of the Chinese varieties were mostly recessive,showing tolerance to both invasion and spreading in expression.Varietal sensitivity to AT toxin and tenuazonic acid had significant correlations separately with invasion and spreading susceptibility to the fungus.Roles of the fungal toxins in pathogenesis and their use in research concerning disease resistance are discussed.The possible applicatien of the differently characterized resistance sources to tobacco breeding is proposed.