OsbZIP47 Is an Integrator for Meristem Regulators During Rice Plant Growth and Development.

Stem cell homeostasis by the WUSCHEL-CLAVATA (WUS-CLV) feedback loop is generally conserved across species; however, its links with other meristem regulators can be species-specific, rice being an example. We characterized the role of rice in vegetative and reproductive development. The knockdown (KD) transgenics showed meristem size abnormality and defects in developmental progression. The size of the shoot apical meristem (SAM) in 25-day plants was increased as compared to the wild-type (WT). Inflorescence of KD plants showed reduced rachis length, number of primary branches, and spikelets. Florets had defects in the second and third whorl organs and increased organ number. SAM and panicles had abnormal expression for CLAVATA peptide-like signaling genes, such as (), (), and hormone pathway genes, such as cytokinin (CK) (), (), auxin biosynthesis 7 and gibberellic acid (A) biosynthesis genes, such as () and (). The effects on (), , and () relate to the second and third whorl floret phenotypes in . Protein interaction assays showed OsbZIP47 partnerships with RICE HOMEOBOX1 (OSH1), RICE FLORICULA/LEAFY (RFL), and OsMADS1 transcription factors. The meta-analysis of KD panicle transcriptomes in , , and transgenics, combined with global OSH1 binding sites divulge potential targets coregulated by OsbZIP47, OsMADS1, OSH1, and RFL. Further, we demonstrate that OsbZIP47 redox status affects its DNA binding affinity to a element in , a target locus. Taken together, we provide insights on roles in SAM development, inflorescence branching, and floret development.