Abstract Detail

Recent Topics Posters

Gou, Xiaoping [1], Yuan, Tong [1], Wei, Xiaoping [1], Russell, Scott D. [1].

Gene expression in the dimorphic sperm cells of the angiosperm, Plumbago zeylanica.

Mature pollen of the flowering plant Plumbago zeylanica contains dimorphic sperm cells that differ in organization and fate. One sperm cell (Svn) is physically associated with the vegetative nucleus, whereas the other sperm cell (Sua) is unassociated with it, but linked with the Svn. Their fate during fertilization is known to be preferential, with the Sua fusing with the egg cell in >95% of cases (forming the zygote and embryo), while the Svn fuses with the central cell (forming the nutritive endosperm) during double fertilization. To determine whether gene expression differences relating to fertilization fate occur in the two sperm cells, we isolated mRNA from each sperm cell population, created PCR-cDNA libraries (both representative and subtracted) and characterized products using ESTs, microarrays, qRT-PCR and in situ hybridization. Large numbers of ESTs yielded no hits (43%), unclassified and hypothetical proteins accounted for 17%, and the remaining 40% were functionally categorized. Expression profiles based on products examined using qRT-PCR reveal that approximately 50% were uniquely or highly expressed only in sperm cells when screened against other tissues (pollen at three different stages, stem, root, petal, sepal, and ovary). Sequences for nearly 2000 clones are posted at URL: http://www.genome.ou.edu/plumbago.html with 1522 in GenBank. To screen for products with differential expression in the two sperm, we made suppression subtraction hybridization (SSH) PCR-amplified libraries and spotted 2304 clones from each library onto glass slides for microarray screening. Many clones expressed differential expression patterns in the two sperm cell types. From these candidates, we obtained several products expressed in only one sperm cell, corroborated by whole mount in situ hybridization. We also isolated sperm-specific promoters displaying activity with GFP or GUS reporters in Arabidopsis sperm cells. The richness and diversity of mRNAs present in sperm cells is unexpected.

1 - University of Oklahoma, Department of Botany and Microbiology, 770 Van Vleet Oval, Norman, Oklahoma, 73019, USA

Keywords:
preferential fertilization
dimorphic sperm
Plumbago zeylanica
qRT-PCR
Gene expression
cDNA library.

Presentation Type: Recent Topics Poster
Session: 33-132
Location: Salon C, D & E - Gov Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 12:30 PM
Abstract ID:658