Résumé
Auxin plays a crucial role in various aspects of plant development and reproduction. In gametophytic apomixis, clonal embryos arise from unreduced egg cells through parthenogenesis. In Paspalum notatum, parthenogeneticembryos can be observed in some aposporous embryo sacs prior to anthesis, and their number increases following exogenous auxin application (auxin test). Recently, we identified a homolog of the auxin-responserepressor AtIAA16, named PnIAA30, within the P. notatum Apomixis Controlling Locus (ACL). Expression analyses revealed that PnIAA30 transcripts are downregulated in the ovules of apomictic genotypes compared to sexualones at anthesis and 1-3 days post-anthesis (early embryogenesis). Moreover, in situ hybridization showedspatial and temporal differences in PnIAA30 expression between sexual and apomictic ovules. In Arabidopsis,a known interactor of AtIAA16 is ARF5/MONOPTEROS (MP), an activator of auxin-responsive genes. ARF5/MP positively regulates DORNRÖSCHEN/ENHANCER OF SHOOT REGENERATION 1 (DRN/ESR1), an AP2 transcriptionfactor involved in embryonic patterning, auxin perception, and transport. The aim of this study was to analyze DRN expression levels in reproductive tissues of sexual and apomictic P. notatum genotypes to evaluatewhether differences in auxin signaling responses correlate with reproductive mode. Mining the transcriptome of reproductive tissues from both genotypes revealed four DRN isoforms, one of which characterized by a specificdeletion, was significantly overexpressed in apomicts across all developmental stages analyzed. qRT-PCR assays confirmed the overexpression of DRN transcripts in apomictic genotypes at the post-anthesis stage. Additionally,DRN expression levels increased following exogenous auxin treatment. Our findings indicate that a specific DRN/ESR1 isoform is upregulated in the apomictic transcriptome throughout development and confirm that DRN/ESR1 expression levels are modulated in response to auxin treatment. This evidence underscores the potential importance of investigating the functional relationship among PnIAA30, MP, and DRN, which may link auxinsignaling to the regulation of apospory and parthenogenesis.