Overexpression of MtDof32 in Medicago truncatula enhances leaf and flower organ size through modulation of cell expansion

As leaf organ size is a key determinant of plant morphology and development, elucidating the cellular and molecular mechanisms governing organ size regulation has become a central research focus in legume biology. <i>DNA binding with one finger 32</i> (<i>MtDof32</i>), previously identified as a key regulatory factor in organ development, has been shown to influence leaf and flower organ size in <i>Arabidopsis</i>. Here, we demonstrated that <i>MtDof32</i> overexpression in <i>Medicago truncatula</i> resulted in the enlargement of both leaf and flower organs. Cellular analysis revealed that <i>MtDof32</i> primarily modulated organ size by controlling cell expansion. Yeast two-hybrid, co-immunoprecipitation (Co-IP), and bimolecular fluorescence complementation (BiFC) assays collectively established the nuclear-localized interaction between MtDof32 and MtEBP1. Additionally, we observed that <i>MtDof32</i> overexpression led to delayed flowering and reduced branching in transgenic plants. Comparative analysis with wild-type plants indicated significant alterations in the expression levels of key flowering and branching regulatory genes. This study underscored the conserved role of <i>MtDof32</i> in regulating organ size across leguminous species, offering valuable insights for the genetic modification and utilization of this gene in crop improvement strategies.