Abstract

My lab’s work focused on small RNAs in plants; most recently, we’ve been investigating the biogenesis, roles, and evolutionary diversification of pathways that give rise to “secondary” small interfering RNAs (siRNAs), more specifically, those triggered by microRNAs and generated in an unusual “phased” pattern. In 2015, we published work from maize in which we demonstrated the temporal and spatial distribution of two sets of these “phasiRNAs”; we showed that they are extraordinarily enriched in the male germline of the grasses. These comprise the 21-nt (pre-meiotic) and 24-nt (meiotic) siRNAs. These phased siRNAs show striking similarity to mammalian “piRNAs” in terms of their abundance, distribution, distinct stage, and timing of accumulation, but have independent evolutionary origins. Interestingly, the functions for these small RNAs in both plants and animals remain poorly characterized. To better understand these small RNAs, including their evolutionary origins, we are investigating the presence of reproductive phasiRNA pathways in monocots that are relatively divergent from the grasses. I will describe our ongoing analyses of small RNAs, particularly these reproductive phasiRNAs.