Gou, Xiaoping , Wei, Xiaoping , Yuan, Tong , Russell, Scott D. .
Transcriptional profiling and gene expression of flowering plant sperm cells.
OCCURRING within pollen as non-motile cells, sperm are dependent on their surrounding pollen cytoplasm to meet their cellular requirements, possessing sufficient complexity to achieve cellular recognition, adhesion and fusion through passive transport. However, genomic level microarray data indicate that rice sperm cells (Oryza sativa spp. japonica) express over 12,000 genes—1,000 to 2,500 of which are not found in pollen or vegetative sporophyte. This wealth of transcriptional products is surprisingly consistent with expressional profiles of other eukaryotic organisms, including humans. To understand their role, we examined suppression subtractive hybridization-derived ESTs of the target-specific sperm cells of Plumbago zeylanica and found that their expressional profiles conform not to targeting per se, but to the physiology of their respective fusion products. While sperm cells targeted to fuse with the egg cell have greater representation of transcription, translation, post-translation and DNA replication transcripts, the sperm cell targeted to fuse with the central cell has a greater representation of energy- and biosynthesis-related transcripts, consistent with precocious endosperm development. Using a Plumbago sperm promoter construct of isopentenyl transferase (IPT) ligated to GUS (or GFP) reporters, we transformed Arabidopsis plants, which expressed this product in their sperm cells. Upon fertilization, female target cells displayed reporter label from the time of sperm deposition, and later in the early embryo and endosperm—persisting for days. Using this promoter as an indicator of a class of sperm-transmitted transcripts, we postulate that transiently expressed sperm-introduced mRNA transcripts are translated into stable products that may influence the course and pace of development during early embryogenesis and endosperm development. This model of novel sperm cell transcripts gaining expression in the early post-fusion gametes forms part of a novel pattern of transient expression that may be present in sperm cells of many eukaryotes, explaining in part the diversity of sperm cell mRNAs.
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Plumbago sperm cell EST site
Russell Lab Web site
1 - University of Oklahoma, Department of Botany and Microbiology, 770 Van Vleet Oval, Norman, Oklahoma, 73019, USA
sperm cell biology
Presentation Type: Oral Paper:Papers for Sections
Date: Tuesday, August 1st, 2006
Time: 2:00 PM