Genetic variation for pod shatter resistance among lines of oilseed rape developed from synthetic B-Napus

Variation for a wide range of plant characters, more extensive than that normally found in oilseed rape, has been characterised within a Brassica napus genetic background developed from three synthetic Lines of B. napus which had been produced previously from crosses between wild diploid B. oleracea and wild diploid B. rapa species. These synthetic lines were crossed with three oilseed rape cultivars from which were produced three doubled haploid populations of B. napus. These populations were grown as spaced plants in the field and measurements made on plant, raceme and pod architecture so that any new variation could be assessed. Laboratory procedures have been developed to measure the level of resistance to pod shattering among these populations and to determine the mechanical properties of these pods. Resistance to pod shattering determined in the laboratory was broadly linked to held assessment scores. Genetic Variation in pod shattering resistance which exceeded that found among a selection of modem cultivars has been found among lines of these populations. This variation is associated with the particular diploid Brassica parents used to make the synthetic oilseed rape. There are no significant associations among the measured plant characters except for that between beak length and the force needed to shatter the pods as determined in laboratory tests. This suggests that it should be possible to select for resistance to shattering independently of other agronomic characters. Resistance to shattering appears to be Linked to a failure of the dehiscence zone's cells to degrade and to the presence of extra vascular tissue within this zone. (C) 1998 Elsevier Science B.V. All rights reserved.