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 A. ORTIZ

Foz Iguazú

Congreso; International Congress of Plant Molecular Biology; 2015

A sequence homologous tothe EXS (ERD/XPS/SPX) domain was found in the apomixis-linked BAC clone 346H10of Paspalumsimplex. 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 resembles apospory.The objective of this work was to isolate and analyze the expression patternsof EXS genes in apomictic andsexual genotypes of P. notatum. A conserved 2,290-bp gene fragment wasamplified from genomic DNA of both sexual and apomictic tetraploid plants.Amplicons were almost identical and highly similar to the EXS C-terminus of Zea mays and Oryza sativa. Southern-blothybridization detected at least four copies/alleles of EXS in the species. Analysisof RNAseq of apomictic and sexual flowers showed only one coding isotig in thesexual plant but at least two (one truncated) in the apomict plant. qRT-PCR analysesrevealed that PnEXS wasexpressed during all stages of reproductive development. Nonsignificant differencesbetween sexual and apomictic genotypes were detected. In situ hybridization assays inreproductive organs revealed spatial and chronological altered expression inapomictic and sexual flowers. At anthesis, PnEXS was strongly expressed in the nucellar tissueof the sexual genotype, but only in the border cells of the megagametophyte inthe apomictic one. At meiosis, the sense probe hybridized close to themegaspore mother cell in the apomictic genotype, but not in the sexual. Resultsindicated that expression patterns of EXS differed between sexual and apomicticgenotypes.