Résumé
Micropropagation of oil palm by somatic embryogenesis provides a useful means of exploiting elite genotypes of this economically important species. Clonal progeny obtained by this approach have however been found to contain a variable percentage (averaging 5-10%) of palms bearing the mantled floral abnormality. The latter involves an overall feminisation of both male and female flowers: in the latter, the staminodes (vestigial stamens) develop as pseudocarpel structures which may develop after fertilisation to give mantled fruit. Several key features of the mantled abnormality reveal that it is epigenetic in nature. Firstly, it has been observed that reversion to a normal floral phenotype may occur over a period of years following the onset of flowering. Secondly, although the mantled abnormality is strongly transmitted through tissue culture, only a weak non-Mendelian transmission of the mantled character is observed via seeds. Thirdly, the fact that the abnormal phenotype is unlikely to have resulted from a classical genetic mutation is borne out by ploidy, RAPD and AFLP studies previously carried out in our laboratory. Given that the mantled character is epigenetic in nature, we have used an experimental approach based on differential display analysis as a means of identifying genes which are differentially expressed in a mantled-related fashion. (Résumé d'auteur)