Résumé
Apomixis is an asexual mode of reproduction by seed, which is found in a number of families of higher plants. During apomictic processes, both meiosis and egg cell fertilisation are omitted making offspring exact genetic replicas of the mother plant. To gain an insight into the molecular basis of apomictic reproduction, gene expression in mature ovaries containing reduced and unreduced embryo sacs was compared in Brachiaria, an apomictic tropical forage grass. Experimental systems for the molecular study of apomixis and sexuality have limitations mainly resulting from numerous differences in the genetic make-up of the plant material. When unrelated to the reproductive behaviour, these may dramatically affect the results if a conventional differential display strategy is applied (comparison made on a one-to-one plant basis). To overcome these limitations, we examined mRNA populations extracted from ovaries collected from pooled samples of various apomictic and sexual plants using the polymerase chain reaction (PCR) differential display and non radioactive cDNA detection procedures. Using this approach, two mRNAs whose expression appeared to be related to the late stages of apomictic reproduction were identified. These results indicate that gene expression in pooled mRNA analysis is a promising tool to elucidate the molecular basis of apomixis.