Know more

Flowering plants alternate between multicellular haploid (gametophyte) and diploid (sporophyte) generations. Pollen actively transcribes its haploid genome, providing phenotypic diversity even among pollen grains from a single plant. I will describe two projects aimed at exploring, and ultimately leveraging, the independence of the haploid male gametophyte. In the first project, we established the timing of haploid genome activation during pollen development in maize. Using allele-specific RNA sequencing of single pollen precursors, we observed widespread biallelic expression for 11 days after meiosis, indicating that transcripts synthesized by the diploid sporophyte persist long into the haploid phase. Subsequently, there was a rapid and global conversion to monoallelic expression at pollen mitosis I, driven by active new transcription from the haploid genome. In the second project, we are developing a system to perform genetic screens directly in pollen, allowing millions of gene disruptions to be tested per plant. Ultimately, this can serve as a powerful approach to dissect gene function for any phenotype that can be assessed in pollen.