Morphometric analysis on chromosomes of tropical Pinus species

Foram realizados estudos citogen\ue9ticos em Pinus oocarpa Schiede ex Schltdl., Pinus patula Schltdl. & Cham. e nas proced\ueancias J\uf3con Yoro, Las Camelias e San Rafael del Norte do Pinus tecunumanii Eguiluz & J. P. Perry, visando subsidiar a defini\ue7\ue3o da categoria taxon\uf4mica do Pinus tecunumanii. A caracteriza\ue7\ue3o dos cromossomos mit\uf3ticos, utilizando colora\ue7\ue3o com Giemsa e com o fluorocromo 4', 6- diamidino-2-fenilindoldiidroclor\ueddrico (DAPI), confirmou o padr\ue3o cariot\uedpico descrito para a maioria das esp\ue9cies do g\ueanero, isto \ue9, onze pares de cromossomos metac\ueantricos, muito semelhantes quanto ao comprimento e morfologia, e um par submetac\ueantrico, para todos os taxa estudados. A colora\ue7\ue3o com o fluorocromo forneceu defini\ue7\ue3o clara das constri\ue7\uf5es secund\ue1rias, permitindo a diferencia\ue7\ue3o das esp\ue9cies e proced\ueancias pelo n\ufamero e posi\ue7\ue3o das mesmas. As proced\ueancias de Pinus tecunumanii tamb\ue9m se diferenciaram dos outros dois materiais em rela\ue7\ue3o ao comprimento total do complemento hapl\uf3ide. Os resultados obtidos suportam o "status" espec\uedfico para o Pinus tecunumanii, bem como fornecem evid\ueancias de que al\ue9m das muta\ue7\uf5es de ponto, altera\ue7\uf5es estruturais contribu\uedram para a diferencia\ue7\ue3o intra e interespec\uedfica no g\ueanero Pinus .Karyotypic analysis of Pinus oocarpa Schiede ex Schltdl., Pinus patula Schltdl. & Cham. and of provenances J\uf3con Yoro, Las Camelias and San Rafael del Norte of Pinus tecunumanii Eguiluz & J. P. Perry were accomplished to provide information for definition of Pinus tecunumanii taxonomic status. Characterization of mitotic chromosomes stained with Giemsa and with 4', 6-diamidino-2- phenylindoldihydrochlorid (DAPI) fluorochrome confirmed the karyotypic pattern reported for most of the Pinus species, which present eleven pairs of metacentric chromosomes, very similar in regard to length and morphology, and a submetacentric pair for all the taxa studied. Sharp definition of secondary constrictions revealed by DAPI staining allowed distinction of species and provenances by the number and position of this cytological marker. Pinus tecunumanii was also different from the other two species in regard to total length of haploid set. The results support the species status for Pinus tecunumanii as well as present evidence that in addition to point mutations, structural alterations contributed toward intra and interspecies differentiation into the genus Pinus

Karyotype analysis, DNA content and molecular screening in Lippia alba (Verbenaceae)

Cytogenetic analyses, of pollen viability, nuclear DNA content and RAPD markers were employed to study three chemotypes of Lippia alba (Mill.) (Verbenaceae) in order to understand the genetic variation among them. Different ploidy levels and mixoploid individuals were observed. This work comprises the first report of different chromosome numbers (cytotypes) in L. alba. The chromosome numbers of La2-carvone and La3-linalool chemotypes suggested that they are polyploids. Flow cytometric analysis showed an increase of nuclear DNA content that was not directly proportional to ploidy level variation. A cluster analysis based on RAPD markers revealed that La3-linalool shares genetic markers with La1-citral and La2-carvone. The analysis showed that the majority of genetic variation of La3-linalool could be a consequence of ixoploidy. ur data indicates that sexual reproduction aong those three chemotypes is unlikely and suggests the beginning of reproductive isolation. The results demonstrated that chromosome analysis, nuclear DNA content estimation and RAPD markers constitute excellent tools for detecting genetic variation among L. alba chemotypes