Towards breeding of rapeseed () with alien cytoplasm and powdery mildew resistance from Ethiopian mustard ().

Powdery mildew (PM), caused by , is an epidemic of oil rapeseed ( L.) growing worldwide, but PM resistant germplasm is rare in this species. We screened 102 accessions of and other cruciferous species and found an Ethiopian mustard () cultivar 'White flower' immune to PM in both the field and greenhouse. Outcrossing in the female parent 'White flower' was promoted by using a chemical gametocide tribenuron-methyl, to obtain hybrid seeds of distant hybridization with an elite cultivar 'Zhongshuang11'. Three true F hybrids with cytoplasm were obtained without using embryo rescue, which showed complete male sterility and light yellow petals. The hybrid plants and the progenies derived from backcrossing were validated using morphological traits, seed quality, and molecular markers. Five lines in the BCF generation, named 'W7-1', 'W7-4', 'W7-6', 'W8-1', and 'W8-3', and one BCF line 'W3PS-1', whose young leaf was yellow green, were identified to be resistant or moderately resistant to PM. The seed quality and some morphological traits of these lines resembled the parent 'Zhongshuang11', indicating that the resistance gene(s) has been preliminarily introduced into .