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Análise filogenética de acessos do gênero Heliconia L. (Heliconiaceae) utilizando marcadores moleculares

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ABSTRACT

Dissertação (mestrado)—Universidade de Brasília, Departamento de Botânica, 2009. O gênero Heliconia L. é o único da família Heliconiaceae com aproximadamente 180 espécies de origem neotropical. O gênero foi por diversas vezes associado à família Musaceae, mas hoje forma uma família própria, na ordem Zingiberales. As flores invertidas, a presença de um único estaminóide e os frutos do tipo drupa são características póprias de Heliconia. São comumente utilizadas como plantas ornamentais, sendo crescente sua aceitação como flor de corte. Contudo, existem confusões e incertezas sobre o número de espécies e a relação entre elas, por isso estudos moleculares são necessários para um melhor entendimento dos limites das espécies e dos processos de especiação dessas plantas. O presente trabalho teve por objetivo analisar a variabilidade genética e a filogenia de acessos do gênero Heliconia com base em marcadores RAPD, e sequenciamento de regiões do cloroplasto (trnL, trnL-F, psbA-trnH, psbM-ycf6) e do núcleo (ITS), contribuindo desta forma para o conhecimento da história evolutiva do gênero. Com os marcadores RAPD, foram analisados 124 acessos e 231 marcadores polimórficos, a partir da análise fenética e cladística (Máxima Parcimônia, Inferência Bayesiana), que permitiram identificar o monofiletísmo do gênero Heliconia e agrupamentos correspondentes às espécies analisadas, bem como cultivares e híbridos correspondentes aos seus parentais. Com as sequências plastidiais e nucleares, foram analisados 52 acessos, a partir de três técnicas de análise filogenética (Máxima Parcimônia, Inferência Bayesiana e Máxima Verossimilhança), as quais indicaram o monofiletismo do gênero, concordando com os dados de RAPD. A relação com o grupo externo foi constante para os diferentes tipos de análises realizadas. As sequências plastidiais permitiram identificar os híbridos de Heliconia e seus parentais, e indicaram uma possível divergência na origem dessa organela. Além disso, foram encontrados ramos internos curtos, poucos agrupamentos com suportes aceitáveis e um alto grau de politomia nas árvores de consenso, o que pode indicar uma irradiação rápida e uma diversificação recente do gênero. _________________________________________________________________________________ ABSTRACT The genus Heliconia L. is the sole member of the family Heliconiaceae with approximately 180 species of Neotropical origin. Heliconia has been variously associated with the Musaceae family, but is now placed in its own family in the order Zingiberales. The inverted flowers, the presence of a single staminoide, and the peachlike fruits are special features of Heliconia, wich are commonly used as ornamental plants, with growing acceptance as cut flowers. However, there is confusion and uncertainty about the number of species and the relationships between them, so molecular studies are needed to better understand the limits of the species and the speciation processes of these plants. The aim of this study was to analyze the genetic variability and phylogeny of the genus Heliconia based on RAPD markers and internal transcribed spacer sequences (ITS) of nuclear ribosomal RNA gene and the chloroplast regions (trnL, trnL-F, psbA-trnH, psbM-ycf6), thus contributing to the knowledge of the evolutionary history of the genus. With RAPD markers, 124 accessions were analyzed and 231 polymorphic markers were identfied from the phenetic and cladistic analysis (Maximum Parsimony, Bayesian Inference), which confirmed the monophyly of the genus Heliconia and resolved clusters corresponding to the analyzed species, cultivars, hybrids and their parentals. With chloroplast and nuclear sequences, 52 accessions were analyzed using three phylogenetic analysis techniques (Maximum Parsimony, Bayesian Inference and Maximum Likelihood), which also indicated the monophyly of the genus, in agreement with the RAPD data. Relationships with the outgroup was constant for the different types of tests performed. Chloroplast sequences permited identification of Heliconia hybrids and their parentals, and indicated a possible divergence in the origin of this organelle. Furthermore, internal branches were short, few groups with acceptable support and a high degree of polytomies in the consensus trees, which may indicate a rapid radiation and recent diversification of the genus.

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    • "However, natural variations between individuals and between populations have caused much disagreement among collectors, farmers and researchers (Berry & Kress, 1991). Although the genus has been being the subject of taxonomic revisions, it has been poorly studied, with confusion and uncertainty about the number of species and the relationship between them (Marouelli, 2009). Thus, karyotypic information, from a simple count to detailed molecular studies, is an important aid in taxonomic identification (Stace, 2000). "
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    ABSTRACT: The genus Heliconia is not much studied and the number of existing species in this genus is still uncertain. It is known that this number relies between 150 to 250 species. In Brazil, about 40 species are native and known by many different names. The objective of this paper was to characterize morphometrically and to identify the NOR (active nucleolus organizer regions) by Ag-NOR banding of chromosomes of Heliconia bihai (L) L. Root meristems were submitted to blocking treatment in an amiprofos-methyl (APM) solution, fixed in methanol-acetic acid solution for 24 hours, at least. The meristems were washed in distilled water and submitted to enzymatic digestion with pectinase enzyme. The slides were prepared by dissociation of the root meristem, dried in the air and also on hot plate at 50°C. Subsequently, some slides were submitted to 5% Giemsa stain for karyotype construction and to a solution of silver nitrate (AgNO3) 50% for Ag-NOR banding. The species H. bihai has 2n = 22 chromosomes, 4 pairs of submetacentric chromosomes and 7 pairs of metacentric chromosomes, and graded medium to short (3.96 to 0.67 μM), with the presence of active NOR in pairs 1 and 2 and interphase cells with 2 nucleoli. These are the features of a diploid species.
    Full-text · Article · Jan 2014 · Revista Ceres