Testing and Evaluation of Disease Resistance of Flue-cured Tobacco Varieties(Lines) Introduced From U.S.

For breeding resistant varieties,the resistances of 13 flue-cured tobacco varieties(lines) introduced from the U.S.to tobacco black shank,TMV and tobacco brown spot diseases were tested with inoculation,and the tests to TMV and brown spot diseases were assisted with molecule marking.The results indicated that:1) NCT5,NCT6,NCT7,NCT8,NCT9,NCT10 and NCT13 were resistant,NCT1,NCT4,NCT11 and NCT12 were moderately resistant to tobacco black shank.In molecule marking testing,the dominant black shank resistance gene,Ph,was detectable only in NCT6,NCT9,NCT12 and NCT13.2) To tobacco brown spot disease,NCT1,NCT8,NCT11 and NCT4 were moderately susceptible,NCT12,NCT10,NCT2,NCT13,NCT9,NCT3,NCT7,NCT6 and NCT5 were moderately resistant.3) To TMV disease,NCT13,NCT10,NCT9,NCT12,NCT6,NCT4,NCT1,NCT2,NCT11,NCT7 and NCT8 were susceptible,NCT5 and NCT3 were moderately susceptible.PCR analysis results showed that TMV resistance gene,N,was not detectable in all varieties(lines) mentioned above,which agreed with resistance evaluation results.