Comparative insights into molecular pathways influencing germline development in early-divergent angiosperms

The molecular and genetic mechanisms regulating female germline development remain largely unknown in basal and early-divergent angiosperms. This contrasts with recent progress in model eudicots such as Arabidopsis thaliana and monocots, such as rice, barley, and maize. In this study, we investigate the genetic pathway governing female germline development in the early-divergent angiosperm Annona cherimola. Using a region-specific transcriptome study, key orthologs of germline regulators were identified, followed by spatio-temporal expression pattern analysis and a functional assay. Expression patterns were compared to those in Arabidopsis. While some genes like DMC1 show similar expression patterns across species, most genes display notable differences, though they are still transcribed in or around the germline. AcWUS, despite its differential expression compared to Arabidopsis, maintains its essential role in ovule and plant development. Our findings offer insight into the evolutionary conservation of pathways regulating germline development, highlighting both similarities and differences in the expression of key genes. These may stem from the phylogenetic distance and/or different nucellar morphologies between early-divergent magnoliids and derived eudicots.