Chromosome banding and DNA content in tropical Pinus species

Abstract

The species Pinus tecunumanii Eguiluz & J. P. Perry has been the reason for a taxonomic controversy for more than 50 years. Some authors considered Pinus tecunumanii as a subspecies of Pinus patula, whereas others stated it is a distinct species closer to Pinus oocarpa. In the present work, the tropical species Pinus oocarpa Schiede ex Schltdl., Pinus patula Schltdl. & Cham, and Pinus tecunumanii Eguiluz & J.P. Perry were evaluated as to chromosome banding pattern using CMA3 fluorochrome, to identify chromosome polymorphisms, and as to nuclear DNA content using flow cytometry, to contribute to the differentiation among the three taxa. Analysis of variance and Tukey´s test were used to verify the existence of a significative difference for nuclear DNA content. The obtained CMA3 banding pattern evidenced that secondary constrictions are GC-rich regions and that Pinus tecunumanii is closer to Pinus oocarpa than to Pinus patula. Content of nuclear DNA means were significantly different, with the major mean being observed in Pinus patula (43.36 pg), and the minor one in Pinus tecunumanii, provenance Mountain Pine Ridge (40.48 pg). The intraspecific DNA content variation observed among four different provenances of Pinus tecunumanii was not correlated to their latitudinal origin. The DNA content variation did not allow distinction between Pinus tecunumanii and the remaining two species.