Temporal and spatial expression of genes involved in DNA methylation during reproductive development of sexual and apomictic Eragrostis curvula

SELVA JUAN PABLO; SIENA LORENA; RODRIGO JUAN MANUEL; GARBUS INGRID; ZAPPACOSTA DIEGO; ROMERO JOSE; ORTIZ JUAN PABLO ; PESSINO SILVINA; LEBLANC OLIVIE; ECHENIQUE VIVIANA C

Scientific Reports

Nature

Año: 2017

Recent reports in model plant species have highlighted a role for DNA methylation pathways in theregulation of the somatic-to-reproductive transition in the ovule, suggesting that apomixis (asexualreproduction through seeds) likely relies on RdDM downregulation. Our aim was therefore to explorethis hypothesis by characterizing genes involved in DNA methylation in the apomictic grass Eragrostiscurvula. We explored floral transcriptomes to identify homologs of three candidate genes, for whichmutations in Arabidopsis and maize mimic apomixis (AtAGO9/ZmAGO104, AtCMT3/ZmDMT102/ZmDMT105, and AtDDM1/ZmCHR106), and compared both their spatial and temporal expressionpatterns during reproduction in sexual and apomictic genotypes. Quantitative expression analysesrevealed contrasting expression patterns for the three genes in apomictic vs sexual plants. In situhybridization corroborated these results for two candidates, EcAGO104 and EcDMT102, and revealed anunexpected ectopic pattern for the AGO gene during germ line differentiation in apomicts. Although ourdata partially support previous results obtained in sexual plant models, they suggest that rather thanan RdDM breakdown in the ovule, altered localization of AtAGO9/ZmAGO104 expression is requiredfor achieving diplospory in E. curvula. The differences in the RdDM machinery acquired during plantevolution might have promoted the emergence of the numerous apomictic paths observed in plants.