Epigenetic mechanisms involved in diplospory regulation in weeping lovegrass

ZAPPACOSTA, D.; GARBUS, I.; SELVA, J. P.; CARBALLO, J.; PASTEN MC; GALLARDO, J.; BELLIDO, ANDRÉS; MARCONI, G; ALBERTINI, E.; ECHENIQUE, V.

Bahía Blanca

Workshop; VII Ciclo de seminarios sobre avances en la caracterización genética y molecular de la apomixis; 2020

CERZOS-CONICET

Weeping lovegrass (Eragrostis curvula) is a forage grass with a particular diplosporousapomixiswheremeiosis is absent and sexual and apomictic seeds have equal embryo:endospermploidy ratio. Several lines of evidence show that epigenetic regulation is involved in the expressiveness of the trait, accounting for the variable expression between plants and forthe increase of the frequency of sexual pistils in facultative genotypes triggered by bioticand abiotic stresses. The aim of this study was to associate differences in the reproductivemode to epigenetic mechanisms given by DNA methylation and miRNAs regulation ofgene expression. Firstly, the Methylation Content Sensitive Enzyme ddRAD (MCSeEd) wasused to detect hypermethylated and hypomethylated positions and further associate themwith apomictic (full and facultative) and sexual genotypes. The distribution of differentiallymethylated positions across genes at CG and 6mA shows a peak around the transcriptstart and transcript termination sites, hence regulating gene expression mainly throughthe incorporation of methyl groups on these positions. Gene ontology analysis revealsterms associated to auxins, clathrins, and kinases previously observed in apomictic species.Moreover, some genes differentially expressed related to the reproductive pathway, couldbe linked to the methylation status in the present work. Regarding miRNAs, a targetanalysis allowed the identification of a MADS-box transcription factor and a transposonrepressed in the sexual genotype through specific miRNA-mRNA interactions. AdditionalmiRNA-mRNA pairs specific for sexual or apomictic genotypes were identified in adegradome-based analysis conducted using Oryza sativa database, reinforcing the conceptof apomixis resulting from sexual pathway deregulation.