Poster: Reproductive Development
Abs #
467: Plant gamete gene expression: the final frontier
Although double fertilization in angiosperms was discovered in 1898, we still know nothing about the proteins that mediate gamete recognition and fusion. We constructed a high quality cDNA library from FACs-purified Zea mays sperm cells (Engel et al., The Plant Journal, in press). Sequencing >1000 randomly selected cDNAs from the unamplified sperm library revealed that sperm have a diverse complement of mRNAs. We used RT-PCR to examine the expression of selected sperm transcripts. Interestingly, several of the transcripts that are most similar to hypothetical Arabidopsis proteins are already expressed during the unicellular stage of pollen development. However, at pollen maturity these transcripts appear to be present exclusively in the sperm cells. We used in situ hybridizations to show that at least one transcript, which encodes a plasma membrane-localized protein similar to a hypothetical Arabidopsis protein, is sperm cell-specific in mature pollen. We isolated putative promoters of Arabidopsis homologs of some of the maize sperm transcripts and used them to drive eGFP expression in transgenic Arabidopsis. One construct worked! We can now test the role of specific proteins during fertilization by expression of recombinant proteins and of RNA interference constructs in sperm cells. To develop tools to investigate and manipulate female gametophyte gene expression, we constructed a cDNA library from 300 maize embryo sacs. http://www.pgec.usda.gov/McCormick/McCormick/mclab.html
