Molecular characterization and expression analysis of an apomixis-linked EXS genes in sexual and apomictic Paspalum notatum

PODIO, MARICEL; DELGADO LUCIANA; PESSINO, SILIVINA CLAUDIA; PUPILLI, FULVIO; JUAN PABLO, ORTIZ

Foz de Iguazú

Congreso; 1. 11th International Congress of Plant Molecular Biology; 2015

A sequence homologous to the EXS (ERD/XPS/SPX)domain was found in the apomixis-linked BAC clone 346H10 of Paspalum simplex. EXS function in plantsis still unknown, but a truncated form of this domain had been associated withproliferation in otherwise arrested cells in yeast, a function that resemblesapospory. The objective of this work was to isolate and analyze the expressionpatterns of EXS genes in apomicticand sexual genotypes of P. notatum. Aconserved 2,290-bp gene fragment was amplified from genomic DNA of both sexualand apomictic tetraploid plants. Ampliconswere almost identical and highly similar to the EXS C-terminus of Zea mays and Oryza sativa. Southern-blot hybridization detected at least fourcopies/alleles of EXS in the species.Analysis of RNAseq of apomictic and sexual flowers showed only one codingisotig in the sexual plant but at least two (one truncated) in the apomictplant. qRT-PCR analyses revealed that PnEXSwas expressed during all stages of reproductive development. Non-significantdifferences between sexual and apomictic genotypes were detected. In situ hybridization assays inreproductive organs revealed spatial and chronological altered expression in apomicticand sexual flowers. At anthesis, PnEXSwas strongly expressed in the nucellar tissue of the sexual genotype, but onlyin the border cells of the megagametophyte in the apomictic one. At meiosis, thesense probe hybridized close to the megaspore mother cell in the apomicticgenotype, but not in the sexual. Results indicated that expression patterns ofEXS differed between sexual and apomictic genotypes.