INVESTIGADORES
PESSINO Silvina Claudia
congresos y reuniones científicas
Título:
Cytosine methylation in a back-and-forth ploidy altered series of diplosporous weeping lovegrass (Eragrostis curvula)
Autor/es:
OCHOGAVÍA A; ECHENIQUE V; PESSINO SC
Lugar:
Wernigerode, Alemania
Reunión:
Congreso; 3rd International Apomixis Conference Wernigerode Germany; 2007
Institución organizadora:
IPK Gatersleben Alemania- Universidad de Perugia, Italia
Resumen:
Eragrostis curvula is a perennial subtropical grass native from Southern Africa. The natural races of this species are autopolyploids that reproduce by obligate apomixis of the pseudogamous diplosporous type. A recent study proved that tissue culture-induced genomic dihaploidization of E. curvula genotypes generated genetic polymorphisms that reverted in a highly reproducible way after colchicine re-doubling, to recreate the original fingerprinting profile.   The objective of this work was to examine the cytosine methylation status of the same ‘back-and-forth’ Eragrostis curvula euploid series by using MSAP (methylation sensitive amplification polymorphims).   The series under study consisted of an apomictic tetraploid genotype (T, 2n = 4x = 40), a sexual dihaploid derivative obtained from T by in vitro culture (D, 2n = 2x = 20) and two tetraploid sexual plants originated from D by independent colchicine treatments (C and M, 2n = 4x =40). A total of 604 MSAP bands were examined, from which 53 (8.7%) showed DNA methylation alterations during the dihaploidization process. Reversion of the methylation profiles was analysed in both colchiploids. Around 70 % of the bands polymorphic between T and D reverted to the original methylation profile when the original ploidy level was restored. However, the phenomenon was not fully reproducible, since each colchicine treatment induced the reversion of a rather different set of bands. Clustering analysis demonstrated that the profiles originated from HpaII reverted more frequently than those originated from MspI, which suggests that a particular pattern of methylation is involved in reversions. Four fragments with revertant methylation were sequenced. All corresponded to coding regions: a transcription factor with a HAT dimerization domain, a retrotransposon protein, a glycolipid transfer protein and a receptor kinase.   These results suggest that dihaploidization induce a general repatterning of the DNA cytosine methylation affecting coding regions in E. curvula. If the original ploidy level is restored, the initial methylation profile is partially restituted, in a non-reproducible basis that depends on the doubling event. The possible link of this ploidy-dependent methylation repatterning with the rise of phenotypes associated with a given ploidy level (i.e. apomixis) remains to be elucidated.