Epigenetic Mechanisms Involved in Diplospory Regulation in Weeping Lovegrass.

ZAPPACOSTA DIEGO; GARBUS INGRID; SELVA JUAN PABLO; CARBALLO JOSE; PASTEN MARÍA CIELO; GALLARDO JIMENA; BELLIDO ANDRÉS MARTÍN; MARCONI G; ALBERTINI EMIDIO; ECHENIQUE VIVIANA

Workshop; VII Ciclo de Seminarios sobre avances en la Caracterización Genética y Molecular de la APOMIXIS; 2020

CONICET

Weeping lovegrass (Eragrostis curvula) is a forage grass with a particular diplosporousapomixis where meiosis is absent and sexual and apomictic seeds have equal embryo:endosperm ploidy ratio. Several lines of evidence show that epigenetic regulation isinvolved in the expressiveness of the trait, accounting for the variable expression betweenplants and for the increase of the frequency of sexual pistils in facultative genotypes triggeredby biotic and abiotic stresses. The aim of this study was to associate differences inthe reproductive mode to epigenetic mechanisms given by DNA methylation and miRNAsregulation of gene expression. Firstly, the Methylation Content Sensitive EnzymeddRAD (MCSeEd) was used to detect hypermethylated and hypomethylated positionsand further associate them with apomictic (full and facultative) and sexual genotypes. Thedistribution of differentially methylated positions across genes at CG and 6mA shows apeak around the transcript start and transcript termination sites, hence regulating geneexpression mainly through the incorporation of methyl groups on these positions. Geneontology analysis reveals terms associated to auxins, clathrins, and kinases previously observed in apomictic species. Moreover, some genes differentially expressed related to thereproductive pathway, could be linked to the methylation status in the present work. RegardingmiRNAs, a target analysis allowed the identification of a MADS-box transcriptionfactor and a transposon repressed in the sexual genotype through specific miRNA-mRNAinteractions. Additional miRNA-mRNA pairs specific for sexual or apomictic genotypeswere identified in a degradome-based analysis conducted using Oryza sativa database, reinforcing the concept of apomixis resulting from sexual pathway deregulation.