Crop domestication as a step towards reproductive isolation

Speciation, Darwin's mystery of mysteries, is a continuous process that results in genomic divergence accompanied by the gradual increment of reproductive barriers between lineages. Since the beginning of research on the genetics of speciation, several questions have emerged such as: What are the genetic bases of incompatibilities? How many loci are necessary to prevent hybridization and how are they distributed along genomes? Can speciation occur despite gene flow and how common is ecological speciation? Early stages of divergence are key to understand the ecology and genetics of speciation, and semi-isolated species where hybrids can still be produced are particularly relevant This article is protected by copyright. All rights reserved.

Isolation and characterization of a satellite DNA family in the Saccharum complex

EaCIR1, a 371-bp Erianthus-specific satellite DNA sequence, was cloned from TaqI restricted genomic DNA after agarose-gel electrophoresis. This sequence has 77% homology with a 365-bp satellite of Helictotrichon convolutum and 72% homology with a 353-bp tandem repeat sequence from Oryza sativa. PCR primers defined in the conserved regions of these repetitive sequences were used to isolate other satellite DNAs in different representatives of the Saccharum complex: SoCIR1 in Saccharum officinarum, SrCIR1 in Saccharum robustum, SsCIR1 and SsCIR2 in Saccharum spontaneum, and MsCIR1 in Miscanthus sinensis. EaCIR1 and SoCIR1 were localized to subtelomeric regions of the chromosomes by fluorescence in situ hybridization. Southern hybridization experiments, using two representatives of this repeat sequence family as probes, illustrated contrasting species-specificity and demonstrated the existence of similar repetitive elements in sorghum and maize.