The vesicle trafficking regulator PN_SCD1 is demethylated and overexpressed in florets of apomictic Paspalum notatum genotypes

Apomixis (asexual reproduction through seeds) is considered a deviation of the sexual reproductive pathway leading to the development of clonal progenies genetically identical to the mother plant. Here we used the Methylation-Sensitive Amplification Polymorphism (MSAP) technique to characterize cytosine methylation patterns occurring in florets of sexual and aposporous Paspalum notatum genotypes, in order to identify epigenetically-controlled genes putatively involved in apomixis development. From twelve polymorphic MSAP-derived sequences, one (PN_6.6, later renamed PN_SCD1) was selected due to its relevant annotation and differential representation in apomictic and sexual floral transcriptome libraries. PN_SCD1 encodes the DENN domain/WD repeat-containing protein SCD1, which interacts with RAB GTPases- and/or MAPKs to promote specialized cell division, functions in clathrin-mediated membrane transport and acts as potential substrate receptor of CUL4 E3 ubiquitin ligases. Quantitative RT-PCR and comparative RNAseq analyses of laser microdissected nucellar cells confirmed PN_SCD1 upregulation in florets of apomictic plants and revealed that overexpression takes place just before the onset of apospory initials. Moreover, we found that several SCD1 molecular partners are expressed in P. notatum florets and upregulated in apomictic plants. Our results disclosed a specific vesicle trafficking molecular pathway epigenetically modulated during apomixis.