Analyses of mitochondrial DNA structure and expression in three cytoplasmic male-sterile chicories originating from somatic hybridisation between fertile chicory and CMS sunflower protoplasts
Analyses of mitochondrial DNA structure and expression in three cytoplasmic male-sterile chicories originating from somatic hybridisation between fertile chicory and CMS sunflower protoplasts
Dubreucq, A.B.rthe, B.A.set, J.; Boulidard, L.B.dar, F.V.sseur, J.R.mbaud, C.
Theoretical and applied genetics 99(7-8): 1094-1105
1999
Cytoplasmic male-sterile (CMS) chicories have been previously obtained by somatic hybridisation between fertile industrial chicory protoplasts and CMS sunflower protoplasts. In this study, we compared three different CMS chicory cybrids that originated from three different fusion events. The cybrids were backcrossed with different witloof chicories in order to transfer the three male-sterile cytoplasms from an industrial chicory nuclear environment to a witloof chicory nuclear context. Southern hybridisation, using different mitochondrial genes as probes, revealed that the three cybrid mitochondrial genomes were different and that they were stable throughout backcrossing generations regardless of the pollinator. However, pollinators were found to influence floral morphologies - with one being able to restore fertility - showing that nuclear context can affect the sterility of the cybrids. PCR and RFLP analyses revealed that the orf522 sequence, responsible for CMS in PET1 sunflower, was present in two out of the three cytoplasms studied, namely 411 and 523, but was absent from the other cytoplasm, 524. We thus concluded that orf522 is not responsible for CMS in the 524 cybrid. Although the orf522 gene is present in the 411 and 523 cytoplasms, it is probably not responsible for the sterile phenotype of these cybrids.