Genes modulating the increase of sexuality in the facultative apomictic grass Eragrostis curvula under water stress conditions

SELVA, J. P.; RODRIGO, J.M.; GALLARDO, J.; CARBALLO, J.; GALLO, C.A.; ZAPPACOSTA, D.; BELLIDO, ANDRÉS; ECHENIQUE, V.

Bahía Blanca

Workshop; VII Ciclo de seminarios sobre avances en la caracterización genética y molecular de la apomixis; 2020

CERZOS-CONICET

Previous reports in Eragrostis curvula, a diplosporous apomictic forage grass, showedthat facultative apomictic genotypes reduce the proportion of apomictic embryo sacsunder stressful conditions like in vitro culture and drought. Here, we report the cytoembryologicaland transcriptomic analysis of inflorescences of facultative apomictic plantsunder control and drought stress treatment in order to identify the mechanisms regulatingthe switch from sexual to asexual reproduction. Embryo sacs from control andstressed plants (161 and 172, respectively) were analyzed, and RNA-Seq Illumina librarieswith three biological replicates from inflorescences of control and stressed plants weresequenced. The percentage of sexual embryo sacs increased from 4 to 24% and 501 outof 201,011 transcripts were differentially expressed (DE) between control and stressedplants (151 upregulated and 350 downregulated in stressed plants). Out of these, 380 wereannotated and analyzed using BLAST2GO and KEGG. DE transcripts were comparedwith previous transcriptomes where apomictic and sexual genotypes were contrasted. Theresults point as candidates to transcripts related to methylation, ubiquitination, hormoneand signal transduction pathways, transcription regulation, and cell wall biosynthesis,some acting as a general response to stress, and some that are specific to the reproductivemode. We suggest that a DNA glycosylase EcROS1-like could be demethylating, thusde-repressing a gene or genes involved in the sexual pathway. Many of the other DEtranscripts could be part of a complex mechanism that regulates apomixis and sexualityin this grass, the ones in the intersection between control/stress and apo/sex being thestrongest candidates.