Plays a major role in the promotion of the transition of the vegetative meristem to reproductive development (PubMed:16240176). Required for RNA-mediated chromatin silencing of a range of loci in the genome. Cotranscriptionally recognizes aberrant RNA and marks it for silencing. Controls alternative cleavage and polyadenylation on pre-mRNAs and antisense RNAs (By similarity). Regulates flowering time, seed size and cell volume, probably via the modulation of cell size (PubMed:17597396). Interacts with FY (PubMed:16820865, PubMed:18854333, PubMed:19561057). Binds to SF1, FIK, RPRD1B, Os09g0509000/LOC_Os09g33480 and MADS8 (PubMed:19561057). Additional isoforms alpha and beta seem to exist. Mostly expressed in young flowers (panicles) and stems, and also present in young seedlings leaves and roots. Mainly observed at earlier stages of panicle development (PubMed:16240176). Up-regulated in young spikelet of primary branch-differentiating stage and down-regulated in young spikelet of pistil and stamen-differentiating stage (PubMed:16753815). Accumulates in differentiating calli (PubMed:16753815). Major isoform.