Submitted to: Plant and Animal Genome VX Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/1/1998
Publication Date: N/A
Technical Abstract: Buffelgrass (Pennisetum ciliare (L.) Link) is an excellent model to study apomictic reproduction due to the presence of obligate apomictic and sexual genotypes. Apomixis is a method of reproduction whereby seeds are formed asexually, either directly from somatic cells or through parthenogenetic development of egg cells in unreduced embryo sacs. Buffelgrass exhibits apospory, a form of gametophytic apomixis where the female gametophyte is formed directly from somatic cells in the ovule. The focus of the research reported here is to elucidate molecular basis of apospory in buffelgrass. cDNA libraries from pistil and spikelet tissues of these genetically distinct lines have been developed. Twelve cDNA clones (Pcp1 to Pcp12) that were preferentially expressed in pistil were identified (using virtual subtraction) and characterized from the apomictic pistil cDNA library. BLAST analyses of nucleotide sequences showed that 7 clones were highly homologous to known genes in GenBank database, while the other 5 represent novel genes. Differential expression was further analyzed by in situ hybridization. Distinct differences in localized expression in specific regions of the pistil were observed for 8 clones. Pcp1, Pcp3 and Pcp4 as analyzed by in situ hybridization in millet and sorghum pistils, showed similar spatial pattern of gene expression as in buffelgrass, suggesting high degree of conservation in gene sequences/regulation among the 3 grass species. Primarily, these clones could serve as starting point in the differences between obligate apospory and sexuality in buffelgrass. In addition, identification of conserved tissue specific genes are useful in isolating tissue specific promoters that could be employed to drive transgenes of interest in pistils of grasses.