INHERITANCE OF RESISTANCE TO TURNIP MOSAIC-VIRUS IN CHINESE-CABBAGE

Turnip mosaic virus (TuMV) is the most important virus of commercially grown cole crops in many Asian countries, affecting both yield and qu ality. TuMV-infected Chinese cabbage becomes unmarketable because of t he presence of black spots and necrosis often induced by the virus. Re sistance breeding is complicated by the existence of five strains of t he virus, one of which was discovered in 1985 for the first time in Ta iwan. Resistance to strains C1 to C3 is readily available among the Ch inese cabbage germplasm at AVRDC, whereas resistance to strains C4 and C5 is rarely found. To elucidate the inheritance of resistance to TuM V, P-1, P-2, F-1, F-2 and BC1 generations of crosses between the resis tant line '0-2' and three susceptible lines,'E-7','E-9' and 'FL-9', we re inoculated with strains C4 and C5. Segregation ratios obtained by v isual observation and enzyme-linked immunosorbent assay (ELISA) indica te that two recessive genes confer resistance to both TuMV-C4 and TuMV -C5.