GENETIC-VARIATION FOR POD SHATTER RESISTANCE AMONG LINES OF OILSEED RAPE DEVELOPED FROM SYNTHETIC BRASSICA-NAPUS

Variation for a wide range of plant characters, more extensive than th at normally found in oilseed rape, has been characterised within a Bra ssica 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 populati ons 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 lev el of resistance to pod shattering among these populations and to dete rmine the mechanical properties of these pods. Resistance to pod shatt ering determined in the laboratory was broadly linked to held assessme nt scores. Genetic Variation in pod shattering resistance which exceed ed that found among a selection of modem cultivars has been found amon g lines of these populations. This variation is associated with the pa rticular diploid Brassica parents used to make the synthetic oilseed r ape. There are no significant associations among the measured plant ch aracters except for that between beak length and the force needed to s hatter the pods as determined in laboratory tests. This suggests that it should be possible to select for resistance to shattering independe ntly of other agronomic characters. Resistance to shattering appears t o 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 E lsevier Science B.V. All rights reserved.