Probable transcription factor (By similarity). Involved in spikelet transition (Probable). Regulator of starch biosynthesis especially during seed development (e.g. endosperm starch granules); represses the expression of type I starch synthesis genes (PubMed:20713616). Prevents lemma and palea elongation as well as grain growth (PubMed:28066457). May form homodimer (By similarity). Interacts with TPR2/ASP1 (PubMed:26631749). Mostly expressed in roots, seedlings and leaves and, to a lower extent, in stems, panicles and developing seeds (PubMed:20713616). Present in spikelets (PubMed:25817414). Accumulates progressively in panicles. Present at low levels in developing seeds, with a progressive decrease during development (PubMed:20713616). In spikelets, fades out progressively after anthesis (PubMed:25817414). Target of miR172 microRNA mediated cleavage, particularly during floral organ development (Probable). Repressed by SRT1 via epigenetic histone H3K9 acetylation (H3K9ac) regulation (PubMed:27181944). Larger seed size and increased seed mass and yield. Enhanced expression of starch synthesis genes in seeds leading to increased seed amylose content and altered fine structure of amylopectin. Decreased proportion of A chains results in abnormal round and loosely packed starch granules but reduced gelatinization temperature. Belongs to the AP2/ERF transcription factor family. AP2 subfamily.