An AT-hook gene is required for palea formation and floral organ number control in rice

► Rice mutants for two genes with defects in palea were characterized. ► Palea is likely a fusion structure between the central region and marginal region with distinct origins. ► Both the sterile lemma elongation and the floral organ number increase phenotype were enhanced in double mutants. ► The two genes encodes a nuclear-localized AT-hook protein with confirmed DNA-binding activity, and a TCP family transcription factor. ► Several E-function MADS box transcription factors were down-regulated in these mutants.