INVESTIGADORES
DELGADO Luciana
congresos y reuniones científicas
Título:
MOLECULAR CHARACTERIZATION AND EXPRESSION ANALYSIS OF THE APOMIXIS-LINKED EXS GENES IN SEXUAL AND APOMICTIC PASPALUM NOTATUM
Autor/es:
PODIO, MARICEL; DELGADO LUCIANA; PESSINO, SILIVINA CLAUDIA; PUPILLI, FULVIO
Lugar:
Bahía Blanca
Reunión:
Seminario; IV Ciclo de seminarios sobre avances en la caracterización genética y molecular de la apomixis en gramíneas forrajeras; 2014
Institución organizadora:
CERZOS, CONICET-UNS
Resumen:
A sequence homologous to the EXS (ERD/XPS/SPX) domain was found in the apomixis-linked BAC clone
346H10 of Paspalum simplex. A
truncated form of this domain had been associated with proliferation in
otherwise arrested cells in yeast, a function that resembles apospory to some
extent. However the candidate?s function in plants is still unknown. The
objective of this work was to isolate, sequence-characterize and analyze the
expression patterns of EXS genes in
apomictic and sexual genotypes of P. notatum.
A conserved 2,290-bp gene fragment was amplified from genomic DNA of tetraploid
sexual (Q4188) and apomictic (Q4117) plants using heterologous primers. Amplicons
obtained from both genotypes were
almost identical and highly similar to the EXS
C-terminus of Zea mays and Oryza sativa, respectively. Southern-blot hybridization indicated the presence of at least four
copies/alleles of EXS in the species.
qRT-PCR analyses revealed
that PnEXS was expressed in the four
stages of the reproductive development tested (premeiosis, meiosis, postmeiosis
and anthesis) and non-significant differences were detected between sexual and
apomictic genotypes. However, in situ
hybridization experiments revealed that PnEXS displayed a spatially-
and chronologically altered expression pattern in reproductive organs of the
apomictic and sexual flowers. At anthesis, PnEXS
was strongly expressed in the nucellar tissue of the sexual genotype, but only
in the megagametophyte border cells in the apomictic genotype. On the other
hand, at meiosis, the sense probe hybridized in a region close to the megaspore
mother cell in the apomictic genotype but no in the sexual one, suggesting the
existence of an antisense-mediated mechanism leading to downregulate PnEXS expression in the apomict.
Recently, RNAseq analysis allowed characterization of all splice-variants,
alleles or paralogues expressed in P.
notatum flowers. The sexual
genotype showed two isotigs (splice variants/alleles/paralogs) while the
apomictic one showed six. Interestingly, four of the six transcripts expressed in
the apomictic genotype included one or two of the introns previously
characterized in the PnEXS genomic
sequences, suggesting the occurrence of variances in the splicing mechanism. The
transcribed intron segments showed similarity with retrotransposons and
introduced stop codons in the corresponding ORFs. Results presented in this
work indicated that splice variants of PnEXS
without protein-coding capacity are possibly associated with apomixis in P. notatum.