Abstract:
In plants, 21 or 22-nt miRNAs or siRNAs typically negatively regulate target genes through mRNA cleavage or translational inhibition. Heterochromatic or Pol IV are 24-nt and function to maintain heterochromatin and silence transposons. Phased “secondary” siRNAs (phasiRNAs) are generated from mRNAs targeted by a typically 22-nt “trigger” miRNA, and are produced as either 21- or 24-mers via distinct pathways. Our prior work in maize and rice demonstrated the temporal and spatial distribution of two sets of “reproductive phasiRNAs”, which are extraordinarily enriched in the male germline of the grasses. These two sets are the 21-nt (pre-meiotic) and 24-nt (meiotic) siRNAs. Both classes are produced from long, non-coding RNAs, generated by hundreds to thousands of loci, depending on the species. These phased siRNAs show striking similarity to mammalian piRNAs in terms of their abundance, distribution, distinctive staging, and timing of accumulation, but they have independent evolutionary origins. The functions for these small RNAs in plants remain poorly characterized. I will describe our recent work investigating the functions of plant phasiRNAs and their roles in modulating traits of agronomic importance in plants, including male fertility.

Bio:
Blake Meyers is the Director of the UC Davis Genome Center and a Distinguished Professor in the Department of Plant Sciences. Before joining UC Davis in 2024, he was a Principal Investigator at the Danforth Plant Science Center and a Curators’ Distinguished Professor at the University of Missouri. He also held the Edward F. and Elizabeth Goodman Rosenberg professorship at the University of Delaware from 2002 to 2015. Blake is a Fellow of AAAS (2012) and ASPB (2017) and was elected to the US National Academy of Sciences in 2022. He has been the Editor-in-Chief of The Plant Cell since 2020. His research focuses on the roles of small RNAs, particularly phasiRNAs, in plant reproductive biology and their potential use in hybrid crop production.