Journal ArticlePremeiotic 24-nt phasiRNAs are present in the <i>Zea</i> genus and unique in biogenesis mechanism and molecular functionZhan, Junpeng; Bélanger, Sébastien; Lewis, Scott; Teng, Chong; McGregor, Madison; Beric, Aleksandra; Schon, Michael A; Nodine, Michael D; Meyers, Blake C<p>Reproductive phasiRNAs (phased, small interfering RNAs) are broadly present in angiosperms and play crucial roles in sustaining male fertility. While the premeiotic 21-nt (nucleotides) phasiRNAs and meiotic 24-nt phasiRNA pathways have been extensively studied in maize (<italic>Zea mays</italic>) and rice (<italic>Oryza sativa</italic>), a third putative category of reproductive phasiRNAs–named premeiotic 24-nt phasiRNAs–have recently been reported in barley (<italic>Hordeum vulgare</italic>) and wheat (<italic>Triticum aestivum</italic>). To determine whether premeiotic 24-nt phasiRNAs are also present in maize and related species and begin to characterize their biogenesis and function, we performed a comparative transcriptome and degradome analysis of premeiotic and meiotic anthers from five maize inbred lines and three teosinte species/subspecies. Our data indicate that a substantial subset of the 24-nt phasiRNA loci in maize and teosinte are already highly expressed at the premeiotic phase. The premeiotic 24-nt phasiRNAs are similar to meiotic 24-nt phasiRNAs in genomic origin and dependence on DCL5 (Dicer-like 5) for biogenesis, however, premeiotic 24-nt phasiRNAs are unique in that they are likely i) not triggered by microRNAs, ii) not loaded by AGO18 proteins, and iii) not capable of mediating<italic>PHAS</italic>precursor cleavage. In addition, we also observed a group of premeiotic 24-nt phasiRNAs in rice using previously published data. Together, our results indicate that the premeiotic 24-nt phasiRNAs constitute a unique class of reproductive phasiRNAs and are present more broadly in the grass family (Poaceae) than previously known.</p>PNAS2024-05-2110523113Proceedings of the National Academy of Sciences121210027-8424https://doi.org/10.1073/pnas.24022851211754097; 2445607National Science Foundation