1 Dept. of Soil and Crop Sciences, Texas A&M University, College Station, TX 77843-2474 USA 2 DuPont Agricultural Products, Experimental Station E402-2249, Wilmington, DE 19880-0402 USA 3 USDA-ARS, College Station, TX 77843-2474 USA
Buffelgrass (Pennisetum ciliare (L.) Link) is an apomictic C4 grass that is grown for forage throughout the semi-arid tropics. In addition to its value as a forage crop, buffelgrass is an excellent model species for studying apomictic reproduction due to the presence of obligate apomictic and sexual genotypes. Apomixis is an asexual method of reproduction in which seeds are formed either directly from somatic cells (nucellar embryony) or through the parthenogenetic development of egg cells in unreduced embryo sacs (gametophytic apomixis). In the latter case, the female gametophyte is formed either directly from the megaspore mother cell (diplospory) or from somatic cells in the ovule (apospory). The focus of the research reported is to elucidate the molecular basis of apospory using aposporous and sexual lines of buffelgrass. cDNA libraries from pistil and spikelet tissues of these lines have been developed. Twelve novel cDNAs that were preferentially expressed in pistil were identified (using virtual subtraction) and characterized from the apomictic pistil library. Analyses of nucleotide homology of seven clones to available data in GenBank showed that two are putative calcium binding proteins, while the other five represent novel genes. Differential expression was further analyzed by in situ hybridization to localize expression of these clones. Distinct differences in localized expression within the different parts of the pistil were found for six clones. Characterization of five more clones are in progress. The significance of pistil specific genes to apomixis will be discussed. This work is supported by grants from Texas Grain and Grass Gene Initiative and Pioneer HiBred Corporation.
Plant & Animal Genome VII Conference Plant & Animal Genome VII Conference