EVALUATION OF BRASSICA-RAPA L GENOTYPES FOR MICROSPORE CULTURE RESPONSE AND IDENTIFICATION OF A HIGHLY EMBRYOGENIC LINE

Isolated microspore culture techniques are being widely used in Brassi ca breeding programs to generate haploid and doubled haploid plants. A number of factors influence regeneration response in vitro including genotype. In order to assess the effect of genotype on microspore embr yogenesis in B. rapa L. var. oleifera, 17 cultivars and breeding lines were evaluated. Embryos developed from all but one genotype when usin g NLN medium with 17% sucrose, followed by a reduction in sucrose conc entration to 10%, 48 h later. The number of embryos/100 buds differed between genotypes, ranging from 0 to 70. Further studies indicated tha t sucrose concentration and incubation time influenced embryogenesis. Selection studies carried out with an Agriculture and Agri-Food Canada breeding line have resulted in the identification of a highly embryog enic B. rapa line. This line produced thousands of microspore-derived embryos/100 buds and will be useful in mutant selection and gene trans fer as well as biochemical and developmental studies.