Water Stress, Apomixis and Gene Expression in the Diplosporous Grass Eragrostis curvula

Abstract

Eragrostis curvula has become a model to understand apomictic mechanisms, specially diplosporous development since our group have generated many plant and genomic resources to study this trait, like a mapping population, a reference genome, the first high density linkage map, sRNAs and transcriptomes databases. The characterization of the molecular pathways underlying apomixis is a prerequisite to transfer the trait to economically important crops. In nature it is possible to observe mainly facultative genotypes of this grass, which retain a certain percentage of sexual pistils that is increased by external factors such as stress conditions, indicating that some regulators activated by stress could be present affecting the apomixis/sex switch. A series of experiments with E. curvula plants of the facultative apomictic cv. Don Walter under control and water deprivation conditions were performed in order to associate the increase of sexual embryo sacs in apomictic plants with the differential expressed genes in inflorescences. Three control and three stressed plants were used for the experiments. Inflorescences were collected for cytoembryological analysis and for RNA sequencing (Illumina HiSeq1500 platform). As a result, 501 differentially expressed transcripts between control and stressed plants were found, 305 out of them were annotated and their expression mainly coincided with up or downregulated pathways previously associated with apomixis, like ubiquitin mediated proteolysis, RNA degradation and vesicle trafficking molecular pathways among the most relevant. Differentially expressed genes involved in these pathways were downregulated in stressed plants and its role in apomixis is being considered.