Component of SCF(ASK-cullin-F-box) E3 ubiquitin ligase complexes, which may mediate the ubiquitination and subsequent proteasomal degradation of target proteins (By similarity). Together with FL/APO2, involved in the temporal regulation of meristem identity during both vegetative and reproductive developments in an APO2-dependent manner (By similarity). Promotes spikelet formation by suppressing the precocious conversion of inflorescence meristems to spikelet meristems, probably via a positive regulation of class-C floral homeotic genes, but not of class-B genes, and through the control of cell proliferation in meristems (PubMed:21119645). Mediates culm development and strength/diameter enhancement at internodes (PubMed:21119645). Required for the regulation of the plastochron, floral organ identity, and floral determinacy (By similarity). Controls the number of primary rachis branches (PRBs) (PubMed:20151298). May trigger the formation of vascular bundle systems which, consequently, promote carbohydrate translocation to panicles (PubMed:20151298). Involved in ozone-induced grain yield regulation (PubMed:25923431). Protein modification; protein ubiquitination. Part of a putative SCF (ASK/Cullin/F-box) ubiquitin ligase complex (By similarity). Interacts with FL/APO2 (By similarity). Expressed in seedlings, roots, leaves, shoot apical meristem (SAM), developing panicles, and, at lower levels, in developing seeds. Present in the developing vascular bundle systems (PubMed:20151298). In the reproductive phase, first observed in the outer several cell layers of the rachis meristem and primary branch meristems (PubMed:20151298). Confined to panicles primodia and young panicles, particularly in the developing rachis branches (PubMed:20151298). Repressed by ozone. The F-box is necessary for the interaction with ASK proteins. Reduced number of primary rachis branches (PRBs) and of the number of grains per panicle, thus leading to reduced grain yield. Ozone has various impact on different cultivars; O.sativa subsp. japonica cv. Sasanishiki exhibits ozone-induced leaf injury, but no grain yield loss, and, by contrast, O.sativa subsp. indica cv. Habataki has grain yield loss with minimal leaf injury upon ozone treatment. Plants harboring the PBN6 quantitative trait locus (QTL) (e.g. HI1 allele in O.sativa subsp. indica cv. Habataki) exhibit bigger peduncle diameter due to larger vascular bundles and an increased number of primary rachis branches (PRBs) and of the number of grains per panicle, thus leading to increased grain yield. Plants harboring the SCM2 quantitative trait locus (QTL) exhibit both an enhancement of culm strength at internodes and an increased spikelet number leading to higher crop productivity and better grain yield.