An epigenetic approach to disclose apomixis in Eragrostis curvula

CARBALLO, JOSÉ; ZAPPACOSTA, DIEGO; MARCONI, GIANPIERO; GALLARDO, JIMENA; DI MARSICO, MARCO; GALLO, CRISTIAN A.; CACCAMO, MARIO; ALBERTINI, EMIDIO; ECHENIQUE, VIVIANA

Congreso; RAFV 2021: XXXIII Argentinian Meeting of Plant Physiology.; 2021

Apomixis is an asexual reproduction by seeds in which the progeny results genetically identical to the mother plant. Apomixis could revolutionise the agriculture as we know today since its transference to major crops could fix the hybrid vigour for more than one generation. Previous studies from our group suggest that epigenetic mechanisms such as DNA methylation could have a central role in the regulation of apomixis in Eragrostis curvula. In order to probe this the methylation levels of sexual and apomictic plants of E. curvula were assessed using the MCSeEd technique, identifying the CG, CHG, CHH and A methylated contexts in DNA from inflorescences. Diferentially methylated positions (DMP) and regions were evaluated in sexual and full and facultative apomictic cultivars showing the apomictic ones higher levels of DNA methylation. In the differential analyses it was observed an increase of methylated positions mainly in regulatory regions. This behaviour was particularly clear in CG and A contexts and was associated to gene silencing in previous studies. Interestingly, ROS1 and ROS4 genes, responsible for the de-methylation in CG contexts, were found differentially methylated on regulatory regions when compared apomictic vs sexual genotypes. The silencing of ROS1 and ROS4 through methylation implies that other genes could not be expressed in apomictic genotypes, probably de-regulating the sexual pathway and giving rise to the apomictic components. This work also allowed us to identify other differentially methylated genes involved in different regulatory mechanisms, like ubiquitin and auxin pathways.