Differential morphology and transcriptome profile between the incompletely fused carpels ovary and its wild-type in maize

We have isolated a new mutation in maize, incompletely fused carpels (ifc), which results in an open stylar canal on the ovary and an incomplete pericarp at the top of the kernel. The maize ovary derives from the fusion of three carpels; however, the molecular networks regulating maize carpel fusion remain largely unclear. In this study, RNA sequencing (RNA-seq) was performed on wild-type (WT) and ifc ovaries that were collected after carpel fusion defects could be morphologically distinguished. In total, 877 differentially expressed genes were identified. Functional analysis revealed overexpression of genes related to "DNA binding", "transcription regulation", "hormones", and "stress responses". Among the 88 differentially expressed transcription factor (TF) genes, five showed a high degree of conservation (77.7-88.0% amino acid identity) of their conserved domains with genes associated with carpel fusion deficiency in Arabidopsis thaliana, suggesting that these five genes might control carpel fusion in maize. In addition, 30 genes encoding components of hormone synthesis and signaling pathways were differentially expressed between ifc and WT ovaries, indicating complex hormonal regulation during carpel fusion. These results help elucidate the underlying mechanisms that regulate carpel fusion, supporting the functional analysis of genes involved in producing this phenotype.