A MORICANDIA-ARVENSIS - BASED CYTOPLASMIC MALE-STERILITY AND FERTILITY RESTORATION SYSTEM IN BRASSICA-JUNCEA

A cytoplasmic male-sterility system has been developed in mustard (Bra ssica juncea) following repeated backcrossings of the somatic hybrid M oricandia arvensis (2n = 28, MM) B. juncea (2n = 36, AABB), carrying m itochondria and chloroplasts from M. arvensis, to Brassica juncea. Cyt oplasmic male-sterile (CMS) plants are similar to normal B. juncea; ho wever, the leaves exhibit severe chlorosis resulting in delayed flower ing. Flowers are normal with slender, non-dehiscent anthers and excell ent nectaries. CMS plants show regular meiosis with pollen degeneratio n occurring during microsporogenesis. Female fertility was normal. Gen etic information for fertility restoration was introgressed following the development of a M. arvensis monosomic addition line on CMS B. jun cea. The additional chromosome paired allosyndetically with one of the B. juncea bivalents and allowed introgression. The putative restorer plant also exhibited severe chlorosis similar to CMS plants but posses sed 89% and 73% pollen and seed fertility, respectively, which subsequ ently increased to 96% and 87% in the selfed progeny. The progeny of t he cross of CMS line with the restorer line MJR-15, segregated into 1 fertile: 1 sterile. The CMS (Moricandia) B. juncea, the restorer (MJR- 15), and fertility restored Fl plants possess similar cytoplasmic orga nellar genomes as revealed by 'Southern' analysis.