Various factors affecting the culture of Brassica napus and B. juncea mesophyll protoplasts were examined in order to develop suitable culture media for these species. The basic components (salts and vitamins) of culture media K3 and Kao best supported cell division and colony development in protoplast culture of both species. The addition of casamino acids to Kao's medium resulted in colony browning in B. napus genotypes. B. napus protoplasts grew well with glucose as the osmotic stabilizer, whereas B. juncea protoplasts responded better to sucrose. High NAA and low 2,4-D combinations were effective in stimulating colony growth. Colony development was rapid for a range of genotypes cultured with these recommendations in these media and plant regeneration was obtained from protoplast-derived calli in both species.

Broccoli (Brassica oleracea L. italica) hypocotyl protoplasts were fused with mesophyll protoplasts of two B. napus lines, one carrying the Ogura (ogu) cms cytoplasm, and the other carrying a hybrid cytoplasm consisting of ogu mitochondria combined with triazine-tolerance-conferring chloroplasts from ctr cytoplasm. Two male-sterile somatic hybrids were recovered from the fusion of broccoli protoplasts with those of ogu/ctr cybrid B. napus. The ogu mtDNAs and ctr cpDNAs were not altered in these hybrids. Four male-sterile plants were recovered from the somatic hybridization of broccoli with ogu cms B. napus. Three of these possessed mitochondrial genomes that appeared to have resulted from recombination between the ogu and normal B. oleracea (ole) mtDNAs, while the fourth possessed an unrearranged ogu mtDNA. All four of these plants had B. oleracea cpDNA, and none displayed the seedling chlorosis associated with ogu chloroplasts. Most of the plants recovered from these fusions had the chromosome number expected of B. oleracea + B. napus hybrids (2n = 56). The novel cytoplasms may prove to be useful for the molecular analysis of Brassica cms and for the production of hybrid Brassica.

We have assessed the capacity of cultured protoplasts from two tissue sources of several commercially-grown broccoli cultivars to regenerate plants. A procedure that employs hypocotyl protoplasts and a culture medium with a high NAA:2,4-D auxin ratio was developed. The procedure permits highly efficient formation of colonies that regenerate shoots at frequencies of 8-17% with two of the four cultivars tested. The time required for the development of plants from protoplasts was 8-11 weeks. No mtDNA rearrangements were observed among any of 17 analysed regenerants. Double-stranded RNAs were detected in mitochondrial DNA (mtDNA) preparations of some, but not all, regenerants of one of the cultivars.

No abstract

Hayman's diallel cross analysis was employed to investigate the nature of the genetic control and heritability of yield, yield components, and phenological and agronomic characters in F1 and F2 generations of spring faba beans (Vicia faba L.). High-yielding S4 inbred lines from five open-pollinated faba bean cultivars were used as parents to generate complete F1 and F2 diallels. The S5 inbred line parents and the 20 cross combinations were planted in randomized complete block experiments with six replications. All characters in the F1 diallel and in the F2 diallel with the exception of days from planting to maturity met all of the assumptions required for Hayman's diallel analysis. Yield, total dry matter, harvest index, and pods per plant exhibited significant apparent overdominance in both the F1 and F2 diallels. It is concluded that substantial immediate increases in yield and total dry matter could be expected from exploiting the apparent overdominant gene action found for these characters in these crosses via F1 hybrids or synthetics. Key words: total dry matter, harvest index, diallel crosses, inheritance, Vicia faba L.