Cedar Warman (John Fowler Lab) is lead author on a new paper out in PLOS Genetics titled "High expression in maize pollen correlates with genetic contributions to pollen fitness as well as with coordinated transcription from neighboring transposable elements."
Warman C, Panda K, Vejlupkova Z, Hokin S, Unger-Wallace E, Cole RA, et al. (2020) High expression in maize pollen correlates with genetic contributions to pollen fitness as well as with coordinated transcription from neighboring transposable elements. PLoS Genet 16(4): e1008462. https://doi.org/10.1371/journal.pgen.1008462
In flowering plants, pollen is essential for delivering sperm cells to the egg and central cell for double fertilization, initiating the process of seed development. In plants with abundant pollen like maize, sperm cell delivery can be highly competitive. In an added layer of complexity, growing evidence indicates expression of transposable elements (TEs) is more dynamic in pollen than in other plant tissues. How these elements impact pollen function and gene regulation is not well understood. We used transcriptional profiling to generate a framework for detailed analysis of TE expression, as well as for quantitative assessment of gene function during maize pollen development. TEs are expressed early and persist, many showing coordinated activation with highly-expressed neighboring genes in the pollen vegetative cell and sperm cells. Measuring fitness costs for a set of over 50 mutations indicates a correlation between elevated transcript level and gene function in the vegetative cell. We also establish a role in fertilization for the maize gamete expressed2 (Zm gex2) gene, identified based on its specific expression in sperm cells. These results highlight maize pollen as a powerful model for investigating the developmental interplay of TEs and genes, as well as for measuring fitness contributions of specific genes.