RESUMO
Polyploidy, a numerical alteration of the karyotype, is one of the most important mechanisms in plant speciation and diversification, but could also be detected among populations, the cytotypes. For example, Psidium cattleyanum, a polyploid complex, has chromosome numbers ranging from 2n=3x=33 to 2n=12x=132. Polyploidization causes an increase in DNA content, and both modifications may cause alteration in plant growth, physiology, and epigenetics. Based on this possibility, here we aim to verify the influence of the polyploidization on the production of P. cattleyanum essential oil chemotypes. Differences in the DNA contents, as a proxy to different ploidies, were observed and three distinct chemotypes were identified through the chromatographic profile analysis. The Psidium cattleyanum DNA content and qualitative and quantitative characteristics of the essential oils presented a positive relationship. Plants with higher DNA contents presented higher levels of oil production, which was mostly composed of hydrogenated sesquiterpenes, while plants with lower DNA contents produced lower amount of oil, which was mostly composed of hydrogenated monoterpenes. Based on the importance of essential oils, polyploid plants, which present higher DNA content, are recommended as possible matrices for the propagation of new plants with the potential to produce major compounds of agronomic and pharmacological interest.
Assuntos
Óleos Voláteis , Psidium , Sesquiterpenos , DNA , Monoterpenos , Óleos Voláteis/química , Poliploidia , Psidium/químicaRESUMO
Polyploidy, a numerical alteration of the karyotype, is one of the most important mechanisms in plant speciation and diversification, but could also be detected among populations, the cytotypes. For example, Psidium cattleyanum, a polyploid complex, has chromosome numbers ranging from 2n=3x=33 to 2n=12x=132. Polyploidization causes an increase in DNA content, and both modifications may cause alteration in plant growth, physiology, and epigenetics. Based on this possibility, here we aim to verify the influence of the polyploidization on the production of P. cattleyanum essential oil chemotypes. Differences in the DNA contents, as a proxy to different ploidies, were observed and three distinct chemotypes were identified through the chromatographic profile analysis. The Psidium cattleyanum DNA content and qualitative and quantitative characteristics of the essential oils presented a positive relationship. Plants with higher DNA contents presented higher levels of oil production, which was mostly composed of hydrogenated sesquiterpenes, while plants with lower DNA contents produced lower amount of oil, which was mostly composed of hydrogenated monoterpenes. Based on the importance of essential oils, polyploid plants, which present higher DNA content, are recommended as possible matrices for the propagation of new plants with the potential to produce major compounds of agronomic and pharmacological interest.
A poliploidia, uma alteração numérica do cariótipo, é um dos mecanismos mais importantes na especiação e diversificação das plantas, mas também pode ser detectada entre populações, os citótipos. Por exemplo, Psidium cattleyanum, um complexo poliplóide, tem números de cromossomos que variam de 2n=3x=33 a 2n=12x=132. A poliploidização causa um aumento no conteúdo de DNA, e ambas as modificações podem alterar o crescimento, a fisiologia e a epigenética da planta. Com base nessa possibilidade, objetivamos verificar a influência da poliploidização na produção de quimiotipos de óleo essencial de P. cattleyanum. Diferenças nos conteúdos de DNA, representando diferentes ploidias, foram observadas e três quimiotipos distintos foram identificados através da análise do perfil cromatográfico. O conteúdo de DNA de Psidium cattleyanum e as características qualitativas e quantitativas dos óleos essenciais apresentaram correlação positiva. Plantas com maiores conteúdos de DNA apresentaram maiores rendimentos na produção de óleo, que era majoritariamente composto por sesquiterpenos hidrogenados, enquanto plantas com menores conteúdos de DNA produziram menores quantidade de óleo, que era majoritariamente composto por monoterpenos hidrogenados. Com base na importância dos óleos essenciais, plantas poliplóides, que apresentam maiores conteúdos de DNA, são recomendadas como possíveis matrizes para a propagação de novas plantas com potencial para produzir compostos importantes de interesse agronômico e farmacológico.
Assuntos
DNA , Óleos Voláteis , PsidiumRESUMO
The family Myrtaceae is widespread in the Atlantic Forest and is well-represented in the Espírito Santo State in Brazil. In the genus Psidium of this family, guava (Psidium guajava L.) is the most economically important species. Guava is widely cultivated in tropical and subtropical countries; however, the widespread cultivation of only a small number of guava tree cultivars may cause the genetic vulnerability of this crop, making the search for promising genotypes in natural populations important for breeding programs and conservation. In this study, the genetic diversity of 66 guava trees sampled in the southern region of Espírito Santo and in Caparaó, MG, Brazil were evaluated. A total of 28 morphological descriptors (11 quantitative and 17 multicategorical) and 18 microsatellite markers were used. Principal component, discriminant and cluster analyses, descriptive analyses, and genetic diversity analyses using simple sequence repeats were performed. Discrimination of accessions using molecular markers resulted in clustering of genotypes of the same origin, which was not observed using morphological data. Genetic diversity was detected between and within the localities evaluated, regardless of the methodology used. Genetic differentiation among the populations using morphological and molecular data indicated the importance of the study area for species conservation, genetic erosion estimation, and exploitation in breeding programs.