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- Author or Editor: Xin-ke Niu x
Forty-six Chinese cabbage [Brassica campestris spp. pekinensis (Lour) Olsson] lines consisting of open-pollinated cultivars, inbreds, and F1 hybrids from China were screened for seedling resistance to downy mildew (Peronospora parasitica) (Pers.) Ex. Fr. Thirty-seven lines of this collection were screened for turnip mosaic resistance. Five lines showed dual resistance to downy mildew and turnip mosaic. Resistance to downy mildew at the cotyledon stage, expressed as a reduction in the sporulation capacity of P. parasitica, was under dominant monogenic control. Turnip mosaic resistance was expressed as a hypersensitive reaction. Genetic analysis of a cross between turnip mosaic resistant and susceptible parents suggested that resistance was conditioned by 2 dominant genes.
Nectary development in cytoplasmic male sterile (cms) Brassica campestris L. was partially restored through 3 cycles of selection for nectary size and number. No major anatomical differences between nectaries of normal and cms plants were apparent under light and scanning electron microscopes (SEM). Half-sib family analysis of nectary development showed negligible additive genetic variance but a prominent maternal effect. Differential response to selection observed in 3 pedigrees suggests the possibility of capitalizing on nuclear-cytoplasmic diversity for the improvement of nectary function.