INVESTIGADORES
SELVA Juan Pablo
congresos y reuniones científicas
Título:
Gene expression study in diplosporous and sexual Eragrostis curvula genotypes with differing ploidy levels using ests and differential display
Autor/es:
GERARDO D CERVIGNI; NORMA PANIEGO; SILVINA PESSINO; MARINA DIAZ; JUAN P. SELVA; DIEGO ZAPPACOSTA; GERMÁN SPANGENBERG; VIVIANA ECHENIQUE
Lugar:
Wernigerode, Alemania
Reunión:
Congreso; 3º International Conference on Apomixis; 2007
Resumen:
The molecular
nature of gene expression during the initiation and progress of diplosporous
apomixis is still unknown. Moreover, the basis of the close correlation between
diplospory and polyploidy is not clarified yet. A comparative expression
analysis was performed based on ESTs (expressed sequence tags) sequencing and
differential display in near isogenic lines of E. curvula, a diplosporous
apomictic forage grass. A tetraploid
genotype (T, 4x apo), a sexual diploid derivative obtained from tissue culture
(D, 2x sex) and an artificial sexual tetraploid obtained from the diploid seeds
after colchicine treatment (C, 4x sex) were used. A collection of ESTs was generated
from 3 cDNA libraries derived from panicles of the near-isogenic lines and one
from 12 days-old plant leaves. A total of12,295 high-quality ESTs were clustered and assembled, rendering 8,884
unigenes (1,490 contigs and 7,394 singletons). A total of 7,029 (79.11%)
unigenes were functionally categorized by BLASTX analysis against sequences
deposited in public databases, but only 37.80 % could be classified according
to Gene Ontology and 50% using the cereals gene index (GI). From the total of unigenes
derived from the inflorescence libraries, 112 (1.26 %) showed significant
differential expression in individuals with different ploidy level and/or
variable reproductive mode. Independent comparisons between plants with
different reproductive mode (same ploidy) or different ploidy level (same
reproductive mode) allowed the identification of genes modulated in response to
diplosporous development or polyploidization, respectively. A group of genes were
differentially expressed or silenced only in the 4x sex plant, presenting
similar levels of expression in the 4x apo and the 2x sex genotypes.
Differential display analysis showed that, in general, the 4x apo and 4x sex
expression profiles were more related and different from the 2x sex one, but
confirmed the existence of this particular group of genes, in both
inflorescences and leaves. The possible biological significance of this group of genes is that an
increase in ploidy level requires the activation/silencing of it, but for some
reason this activation/silencing fails in the diplosporous plant. It is
tempting to hypothesize that the expression repatterning for a number of genes
during the genetic diploidization process abort in diplosporous plants (the
same expression pattern of the sexual diploid plant is maintained), and maybe
diplospory itself could be the consequence of this failure. The high ratio of
non categorized genes keeps open the possibility of finding new genes involved
in diplospory and its regulation. The 254 EST-SSRs and 190 SNPs detected in
this study will provide valuable resources for mapping the region associated to
diplospory in Eragrostis.