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Surprises in the maize pollen transcriptome: Inbred differences and developmental similarities
Citation:
Cooper, L. D., Z. Vejlupkova, J. Elser, P. Jaiswal, L. S. WATRUD, AND J. E. Fowler. Surprises in the maize pollen transcriptome: Inbred differences and developmental similarities. Presented at Plant Biology 2010, Montreal, QC, CANADA, July 31 - August 04, 2010.
Impact/Purpose:
Pollen is the primary means of gene flow between plants and plant populations and plays a critical role in seed production.
Description:
Pollen is the primary means of gene flow between plants and plant populations and plays a critical role in seed production. Our overall objective is to better understand the molecular and genetic basis of the pollen function. We compared gene expression levels in seedlings, mature pollen and in vitro-germinated pollen from two different inbred lines, B73 and W22 of maize (Zea mays) using a two-color microarray with 58K oligonucleotide probes (Maize Oligonucleotide Array Project). As expected, a large number of probes (~10,000) showed significant expression differences between pollen and seedling. However, in contrast to published results (Ma et al. 2006), a substantial number of probes (~1000) also detected significant differences between the two inbred lines in pollen (as well as in seedling, although these were largely non-overlapping sets). Using primers designed to Z. mays PUT (PlantGDB-Assembled Unique Transcript) sequences corresponding to microarray probes of interest, qRT-PCR experiments were used to validate a subset of the microarray results. In this process, we identified two qRT-PCR probes as appropriate normalization controls, using the geNorm software package. Interestingly, at a stringent statistical cutoff, no probes detected significant quantitative differences between RNA species in mature and germinated pollen. Biologically, this suggests that pollen germination in maize does not rely upon novel transcription patterns; preliminary results using the transcriptional inhibitor actinomycin D are consistent with this hypothesis, as maize pollen germination is relatively insensitive to the drug. Comparative genomics tools are being used in conjunction with these data to identify conserved pollen-enriched genes across angiosperm species.