INVESTIGADORES
PESSINO Silvina Claudia
congresos y reuniones científicas
Título:
Identification of candidate genes showing epigenetic and/or genetic linkage with apomixis in Paspalum notatum
Autor/es:
BOCCHINI, MARIKA; GALLA, GIULIO; PUPILLI, FULVIO; BARCACCIA, GIANNI; ORTIZ, JUAN PABLO AMELIO; PESSINO, SILVINA; ALBERTINI, EMIDIO
Lugar:
Bahía Blanca
Reunión:
Workshop; V Ciclo de seminarios sobre avances en la caracterización genética y molecular de la apomixis; 2016
Institución organizadora:
CERZOS-CONICET
Resumen:
Apomixis is an asexual mode of reproduction described in numerous genera mainly belonging to the Rosaceae, Rutaceae, Compositae, Asteraceae and Poaceae families, which allows for the generation of viable clonal seeds by circumventing meiosis and fertilization. In apomictic plants, the female gamete (the egg) is formed from cells which were not derived from a meiotic process (therefore displaying the somatic chromosome number) and the embryo arises though parthenogenesis. Successful harnessing of apomixis in agriculture would not only facilitate the clonal propagation of any hybrid combination through seeds by an indefinite number of generations, but also alter the current plant breeding paradigm, by simplifying and reducing the costs of the programs aimed at improving varieties of major crops. The genus Paspalum is an attractive biological system for the study of this trait. Particularly in Paspalum notatum, apomixis is associated with a single genomic region with a distorted segregation ratio, showing a dominant behaviour. This ?apospory-controlling region? (ACR) is a large non-recombinant chromosomal sector, plagged with retrotransposons and heavily methylated. Its demethylation was associated with severe depression or parthenogenesis, suggesting that the character could be under epigenetic control. Several genes with a known role in epigenetic regulation have already been implicated in the control of ovule cell-fate specification and embryo sac development.The objective of the research was to identify genes displaying differential methylation profiles in sexual and apomictic Paspalum notatum plants, by using a comparative approach based on the Methylation-Sensitive Amplification Polymorphisms (MSAP) technique. A total of 547 clear and reproducible bands were amplified by using twelve primer combinations. There were no statistically significant differences in the total quantity of methylated cytosines between sexual and the apomictic plants (the average percentages of CCGG methylation were 62.48% and 60.44%, respectively). Twenty-six DNA fragments showing a trend to differential methylation between apomictic and sexual plants were identified. From them, 12 were successfully excised from polyacrylamide gels, cloned, sequenced and used as queries in surveys onto sexual and apomictic Paspalum notatum 454 data libraries. Five sequences revealed positive matches. Three of them (PN_6.6, PN_8.5 and PN_G17, all of them demethylated in apomictic plants) corresponded to protein-coding genes, while PN_2.10 and PN_G44 were similar to retrotransposon sequences. qPCR analysis revealed quantitative overexpression in florets of apomictic plants for the three candidates. PN_6.6 encodes a DENN domain and a WD repeat-containing protein, which interacts with RAB and MAPKs and is involved in cell division and differentiation. PN_8.5 gene encodes a general regulatory factor 7, GF7, GF14 NU, GRF7, which is part of the SERK1 complex. PN_G17 encodes the FAR-RED IMPAIRED RESPONSE 1 protein. Experimental data suggested that PN_8.5 is genetically rather than epigenetically linked to apomixis. qRNAseq expression analysis conducted in laser-microdissected nucellar cells of Paspalum simplex revealed significant overexpression of PN_6.6 in apomictic plants just prior to the onset of aposporous initials. This work led to the identification of three interesting apomixis development candidate genes, which might represent valuable tools for future harnessing of the trait. Further studies are now been conducted in Arabidopsis mutants in order to examine the reproductive phenotypes and infer a possible role in reproductive development.