Analysis of genome polymorphisms and gene differential expression in diploid and tretraploid genotypes of weeping lovegrass (Eragrostis curvula).

MECCHIA, M.; MATERLOTTO, L.; SELVA, J.P.; OLSINA, C.; ECHENIQUE, V.; PESSINO, S.

San Diego, California

Conferencia; XIV Plant and Animal Genome Conference; 2006

Weeping lovegrass (Eragrostis curvula) is an perennial grass widely cultivated in the semiarid regions to feed cattle. Natural tetraploid races reproduce by obligate pseudogamous diplosporous apomixis of the Antennaria type, while artificially produced diploid and tetraploid plants reproduce by sexuality. We analyzed the genomic structure of a tetraploid-diploid-tetraploid euploid series of the species, consisting of an apomictic tetraploid natural genotype (Tanganyka) (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 colchicine treatment (C and M, 2n = 4x =40). RAPD and AFLP analysis using 218 and 128 markers respectively followed by similarity analysis (Jaccard) and clustering (UPGMA) showed a dendrogram displaying two main clusters: T, C and M grouped together with 0.96 similarity while D was placed at 0.72 with respect to the rest of the plants. Surprisingly, our results showed that most of the genomic features altered during the tetraploid-diploid conversion were restituted in the diploid-tetraploid shift, showing that genome alterations produced by a a change of ploidy are reversible. Some of the polymorphic sectors were isolated. cloned and sequenced, showing sequence homology to a soluble P-type ATPase and a methylase. Differential display analysis followed by real-time PCR validation showed several genes presenting differential expression. Some of them corresponded to known sequences encoding a retrotransposon, a yippee family-protein like protein, an isovaleryl CoA deshydrogenase and a succinate dehydrogenase.