Ethylene Production during Development of Mustard (Brassica juncea) and Canola (Brassica napus) Seed

An open, continuous flow system was used to investigate ethylene production during degreening of maturing seed of mustard (Brassica juncea cv Cutlass and cv Lethbridge 22A) and canola (Brassica napus cv Westar and cv Alto). Isolated mustard seed evolved higher amounts of ethylene than those of canola, and this was particularly evident both early in embryogeny and later during the desiccation phase of seed maturation. The silique walls produced negligible amounts of ethylene in both species. The concentrations of ethylene surrounding seed as they matured within siliques were significantly higher in mustard than in canola, and this interspecies difference was greatest during the seed desiccation phase. In mustard, a 4-fold increase in silique internal ethylene levels was apparent during desiccation. In comparison, only a moderate increase in silique-derived ethylene occurred in canola.