NONRADIOACTIVE MESSENGER-RNA FINGERPRINTING TO VISUALIZE GENE-EXPRESSION IN MATURE OVARIES OF BRACHIARIA HYBRIDS DERIVED FROM B-BRIZANTHA, AN APOMICTIC TROPICAL FORAGE

Apomixis is an asexual mode of reproduction by seed, which is found in a number of families of higher plants. During apomictic processes, bo th meiosis and egg cell fertilisation are omitted making offspring exa ct genetic replicas of the mother plant. To gain an insight into the m olecular basis of apomictic reproduction, gene expression in mature ov aries containing reduced and unreduced embryo sacs was compared in Bra chiaria, 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 plan t material. When unrelated to the reproductive behaviour, these may dr amatically affect the results if a conventional differential display s trategy is applied (comparison made on a one-to-one plant basis). To o vercome 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, t wo mRNAs whose expression appeared to be related to the late stages of apomictic reproduction were identified. These results indicate that g ene expression in pooled mRNA analysis is a promising tool to elucidat e the molecular basis of apomixis. (C) 1997 Elsevier Science Ireland L td.