Mapeamento citogenético comparativo em espécies de Glycine Willd

Abstract

Soybean [G. max (L) Merr.] is considered the main cultivated oil plant and also the first oilseed crop and legume sequenced, generating important genomic information. The present work aimed to perform a comparative genomic study, through in situ localization of eight BACs (Bacterial Artificial Chromosomes) sequences belonging to linkage groups G (pseudomolecule 18, four BACs) and J (pseudomolecule 16, four BACs) from G. max (2n = 40) in G. soja (2n = 40), G. syndetika (2n = 40), G. tabacina (2n = 80) and G. tomentella (2n = 78) chromosomes. Cytogenetic analyzes using the probes in G. max, G. soja and G. syndetika showed that seven BACs yielded single markers in only one or two chromosome pairs, except for G. soja with the BAC 176B09 (three pairs) and G. syndetika with BAC93L17 (four pairs). In G. max and G. soja, only 173N15 revealed a DNA repetitive mark when hybridized in situ in pericentromeric and centromeric regions in all chromosomes of G. max and 10 pairs of G. soja, showing differentiation of these regions throughout evolution. Due to the presence of repetitive DNA, the BAC has not been hybridized in the other species.In G. tabacina two BACs of each linkage group hybridized on a pair of homeologous chromosomes, equivalent being viewed some extra markers viewed for the Gm18 BACs. In relation to G. tomentella, only for the BACs of Gm16 (102N16 and 145O12) there was a conservation of synteny as compared with G. max, observing however the presence of some extra signals, such as duplication and translocation. The BACs of Gm18 (97L17 and 176B09) hybridized on different chromosomes (two pairs each) in G. tomentella, what indicate probable chromosomal rearrangements during evolution. For BACs 102N16 (Gm16) in G. tomentella, 93L17 (Gm18) in G. syndetika and G. tomentella and 176B09 (Gm18) in G. soja, one of the extra pairs was associated with a pair of 45S rDNA sites related to possible differences in the intergenic spacers of rDNA sites. It was also observed that for Gm18, the map orientation sequencing appears to be inverted with respect to the chromosome morphology. The results suggest a break of synteny for Gm16 in G. syndetika and G. tomentella and for Gm18 in all analyzed species.