AUTHOR=Prakash Sandhan , Rai Rashmi , Zamzam Mohamed , Ahmad Owais , Peesapati Raghavaram , Vijayraghavan Usha 

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

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.865928

DOI=10.3389/fpls.2022.865928

ISSN=1664-462X

ABSTRACT=<p>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 <italic>OsbZIP47</italic> 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 <italic>OsbZIP47KD</italic> 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. <italic>OsbZIP47KD</italic> SAM and panicles had abnormal expression for CLAVATA peptide-like signaling genes, such as <italic>FON2-LIKE CLE PROTEIN1</italic> (<italic>FCP1</italic>), <italic>FLORAL ORGAN NUMBER 2</italic> (<italic>FON2</italic>), and hormone pathway genes, such as cytokinin (CK) <italic>ISOPENTEYLTRANSFERASE1</italic> (<italic>OsIPT1</italic>), <italic>ISOPENTEYLTRANSFERASE 8</italic> (<italic>OsIPT8</italic>), auxin biosynthesis <italic>OsYUCCA6, OsYUCCA</italic>7 and gibberellic acid (<italic>G</italic>A) biosynthesis genes, such as <italic>GRAIN NUMBER PER PANICLE1</italic> (<italic>GNP1/OsGA20OX1</italic>) and <italic>SHORTENED BASAL INTERNODE</italic> (<italic>SBI/OsGA2ox4</italic>). The effects on <italic>ABBERANT PANICLE ORGANIZATION1</italic> (<italic>APO1</italic>), <italic>OsMADS16</italic>, and <italic>DROOPING LEAF</italic> (<italic>DL</italic>) relate to the second and third whorl floret phenotypes in <italic>OsbZIP47KD</italic>. 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 <italic>OsbZIP47KD</italic>, <italic>OsMADS1KD</italic>, and <italic>RFLKD</italic> 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 <italic>cis</italic> element in <italic>FCP1</italic>, a target locus. Taken together, we provide insights on <italic>OsbZIP47</italic> roles in SAM development, inflorescence branching, and floret development.</p>