Differential expression of a DNA methyltransferase homologous to CMT3/dmt102 in sexual and apomictic genotypes of Eragrostis curvula

SELVA J.P.; SIENA L.; ROMERO J.R.; GARBUS I.; RODRIGO J.M.; ORTIZ J.P.; PESSINO S.; LEBLANC O.; ECHENIQUE V.

Foz do iguaçu

Congreso; 11th International Congress of Plant Molecular Biology; 2015

Apomixis in plants refers to diverse developmental behaviors resulting in asexual reproduction through seeds. Apomictic individuals bypass both meiotic reduction and egg cell fertilization to produce offspring that are genetic replicas of the maternal plant. Different models have been proposed to explain the occurrence of apomixis at the molecular level involving genetic and epigenetic mechanisms. In particular, some evidences suggest that DNA methylation in reproductive tissues plays a role on the establishment of apomixis, as indicated by the loss-of-function of the maize gene dmt102, a homolog of the Arabidopsis CHROMOMETHYLASE3 (CMT3) gene that partially mimics apomictic development. Weeping lovegrass (Eragrostis curvula (Schrader) Nees) is a diplosporous apomictic perennial grass native to Southern Africa. The cDNA sequence of the E. curvula dmt102 gene (Ec_dmt102) was obtained from a flower transcriptome database generated by using the 454 platform (Roche). The phylogenetic analysis showed that Ec_dmt102 belongs to the CMT3/dmt102 clade. qRT-PCR analysis of Ec_dmt102 in flowers of sexual and apomictic genotypes of E. curvula revealed higher expression in the sexual genotype. These results were corroborated by in situ hybridization experiments and are coincident with data obtained in sexual maize and its wild diplosporous relative, Tripsacum. Overall, these observations suggest that diplosporous apomixis in grasses might rely on common mechanisms that alter DNA methylation in reproductive tissues and, ultimately, drive the transcriptional changes required to install apomictic reproduction.