Fluorescent chromosome banding and DNA content in tropical species of Pinus. / Bandeamento cromossÃmico e conteÃdo de DNA em espÃcies tropicais de Pinus

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Several species of the genus Pinus, including some of tropical origin have been widely used in the production of raw materials such as wood and cellulose. Since fifty years ago, Pinus tecunumanii Eguiluz &J. P. Perry species is the center of a taxonomic controversy. Some works considered Pinus tecunumanii as a Pinus patula subspecies, while others considered it as a distinct species closer to Pinus oocarpa. Nevertheless, the results obtained points out the lack of information to a better understanding of the taxonomic status of Pinus tecunumanii. In the present work the tropical species Pinus oocarpa Schiede ex Schltdl., Pinus patula Schltdl. &Cham and Pinus tecunumanii Eguiluz &J. P. Perry, with 2n= 24 chromosomes, were evaluated through fluorescent banding and AgNor techniques to identify the existence of chromossomic polymorphisms and variations in the amount of nuclear DNA, by flow cytometry, which can contribute to the differentiation of the three taxa. Pinus oocarpa and Pinus tecunumanii displayed 12 interstitial bands CMA3+ coincident with the secondary constrictions. Pinus patula showed 12 interstitial bands, also coincident with the secondary constrictions beyond 4 centromeric bands. The pattern of bands CMA3 showed that the secondary constriction regions are rich in GC bases and the Pinus tecunumanii is closer to Pinus oocarpa than to Pinus patula, with regard to this characteristic. The banding with DAPI fluorocrome didnât produce consistent bands to allow the pattern establishment. The AgNOR banding was not established in the methaphases. Only nucleoli in interphase nuclei were clearly observed. Their number ranged from 4 to 10 in the three species and showed a possible inactivation and/or fusion of some of them. Pinus patula displayed the highest content of DNA among the three species with 43.36 pg. There was intraspecific variation in the DNA content of four provenances of Pinus tecunumanii and this does not correlate with latitudinal origin of provenances. The variation in DNA content not allowed the distinction between the three taxa.

ASSUNTO(S)

ciencias exatas e da terra

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