This first monocotyledon high-continuity whole-genome sequence reported outside Poales represents an essential bridge for comparative genome analysis in plants and clarifies commelinid-monocotYledon phylogenetic relationships, reveals Poaceae-specific features and has led to the discovery of conserved non-coding sequences predating monocotinoid–eudicotylingon divergence.
This work sequenced and assembled the draft genome of Theobroma cacao, an economically important tropical-fruit tree crop that is the source of chocolate, and proposed an evolutionary scenario whereby the ten T. cacao chromosomes were shaped from an ancestor through eleven chromosome fusions.
Using comparative genomic DNA in situ hybridization, it is demonstrated that it is possible to distinguish the chromosomes contributed by these two species in an interspecific F1 hybrid and a cultivated clone, R570, and for the first time the occurrence of recombination between the chromosomes of these twospecies.
Results clearly suggest that C. arabica is an amphidiploid formed by hybridisation between C. eugenioides and C. canephora, or ecotypes related to these diploid species, and indicate low divergence between the two constituent genomes of C. Arabica.
An AFLP genetic map based on a selfing population of a specific cultivar, R570, is constructed and the genome coverage was significantly increased, illustrating the difficulty to access large portions of chromosomes, particularly those inherited from S. spontaneum.
A mapping study on the progeny of a selfed cultivar, R570, suggested the prevalence of random pairing between chromosomes, typical of autopolyploids, however, cases of preferential pairing between S. spontaneum chromosomes were also detected.
Variation in sex determination mechanisms among closely related species of tilapiine fishes makes tilapias an excellent model system for studying the evolution of sex chromosomes in vertebrates.
An extensive Quantitative Trait Allele (QTA) mapping study based on a population of 295 progenies derived from the selfing of cultivar R570 shows the presence in the genome of numerous QTAs, with little effects, fluctuating slightly across cycles, on the verge of being perceptible given the experimental resolution.
Detailed sequence comparison between two NBS/LRR RGA clusters in relation to their orthologs in rice and maize suggests their polyphyletic origins, and indicates that the degree of divergence between paralogous RGAs in sugarcane can be larger than that from an ortholog in a distant species.