Distinct classes of 21- and 24-nt phasiRNAs suggests diverse mechanisms of biogenesis and function in rice anther development.

PhasiRNAs (phased small interfering RNAs) are a major class of plant small RNAs (sRNA) known to be key regulators in male reproductive development of maize (Zea mays) and rice (Oryza sativa), among other plants. Earlier research focused primarily on premeiotic 21-nucleotide (nt) phasiRNAs and meiotic 24-nt phasiRNAs, while new studies uncovered a premeiotic class of 24-nt phasiRNAs. The biogenesis and function of these phasiRNAs remain unclear.

Temperature-sensitive male sterility in rice determined by the roles of AGO1d in reproductive phasiRNA biogenesis and function.

Phased secondary siRNAs (phasiRNAs) are broadly present in the reproductive tissues of flowering plants, with spatial-temporal specificity. However, the ARGONAUTE (AGO) proteins associated with phasiRNAs and their miRNA triggers remain elusive. Here, through histological and high-throughput sequencing analyses, we show that rice AGO1d, which is specifically expressed in anther wall cells before and during meiosis, associates with both miR2118 and miR2275 to mediate phasiRNA biogenesis.