Leonardo Pessoa Felix

Cytogenetics and cytotaxonomy of some Brazilian species of Cymbidioid orchids

The Cymbidioid phylad presents the widest chromosome number variation among orchids, with records varying from 2n = 10 in Psygmorchis pusilla to 2n = 168 in two species of Oncidium. In the present work, a total of 44 species were studied belonging to 20 Cymbidioid genera, as a contribution to clarifying the karyological evolution of the group. All the plants investigated were collected in Brazil, mainly in the northeast region. The chromosome variation found was similar to that previously registered in the literature. Chromosome numbers observed were: 2n = 54 (subtribe Eulophiinae), 2n = 44, 46, 92 (subtribe Cyrtopodiinae), 2n = 54, ca. 108 (subtribe Catasetinae), 2n = 52, ca. 96 (subtribe Zygopetalinae), 2n = 40, 80 (subtribe Lycastinae), 2n = 40, 42 (subtribe Maxillariinae), 2n = 40 (subtribe Stanhopeinae), 2n = 56 (subtribe Ornithocephalinae), and 2n = 12, 20, 30, 36, 42, 44, 56, 112, ca. 168 (subtribe Oncidiinae). Interphase nuclei varied widely from simple chromocenter to complex chromocenter types, with no apparent cytotaxonomic value. In the genera Catasetum and Oncidium, the terrestrial and lithophytic species presented higher ploidy levels than the epiphytic species, suggesting a higher adaptability of the polyploids to those habitats. The primary base number x = 7 seems to be associated to the haploid chromosome numbers of most Cymbidioid groups, although n = 7 was observed only in two extant genera of Oncidiinae. For each tribe, subtribe and genus the probable base numbers were discussed along with the possible relationships to the primary base number x1 = 7 admitted for the whole phylad.

Rock outcrop orchids reveal the genetic connectivity and diversity of inselbergs of northeastern Brazil

BackgroundBecause of their fragmented nature, inselberg species are interesting biological models for studying the genetic consequences of disjoint populations. Inselbergs are commonly compared with oceanic islands, as most of them display a marked ecological isolation from the surrounding area. The isolation of these rock outcrops is reflected in the high number of recorded endemic species and the strong floristic differences between individual inselbergs and adjacent habitats. We examined the genetic connectivity of orchids Epidendrum cinnabarinum and E. secundum adapted to Neotropical inselbergs of northeastern Brazil. Our goals were to identify major genetic divergences or disjunctions across the range of the species and to investigate potential demographic and evolutionary mechanisms leading to lineage divergence in Neotropical mountain ecosystems.ResultsBased on plastid markers, high genetic differentiation was found for E. cinnabarinum (FST = 0.644) and E. secundum (FST = 0.636). Haplotypes were not geographically structured in either taxon, suggesting that restricted gene flow and genetic drift may be significant factors influencing the diversification of these inselberg populations. Moreover, strong differentiation was found between populations over short spatial scales, indicating substantial periods of isolation among populations. For E. secundum, nuclear markers indicated higher gene flow by pollen than by seeds.ConclusionsThe comparative approach adopted in this study contributed to the elucidation of patterns in both species. Our results confirm the ancient and highly isolated nature of inselberg populations. Both species showed similar patterns of genetic diversity and structure, highlighting the importance of seed-restricted gene flow and genetic drift as drivers of plant diversification in terrestrial islands such as inselbergs.

Basic chromosome numbers of terrestrial orchids

The chromosome numbers of forty-one Brazilian species belonging to 11 genera of preferentially terrestrial orchids (subfamilies Cypripedioideae, Spiranthoideae, Orchidoideae, and Vanilloideae) were examined. Previous records for these subfamilies were reviewed in order to identify the ancestral chromosome numbers of terrestrial orchids. The variation observed within the subfamilies Spiranthoideae (2n=28, 36, 46, 48 and 92), and Orchidoideae (2n=42, 44, ca. 48, ca. 80, 84, and ca. 168) was similar to that previously reported in the literature. In the subfamily Spiranthoideae, some species of Prescottia (subtribe Prescottiinae) and some genera of Spiranthinae showed a bimodal karyotype with one distinctively large pair of chromosomes. The analysis of chromosome numbers of the genera in subfamilies revealed the predominance of the polyploid series 7, 14, 21, 28, 42 with a dysploid variation of ±1 in each ploidy level. These results suggest that the basic chromosome number of terrestrial orchids is x1=7 for the subfamilies Spiranthoideae and Orchidoideae, as well as other Epidendroid orchids, and that the majority of the genera are composed of palaeopolyploids.

Chloroplast microsatellite markers for the Neotropical orchid genus Epidendrum, and cross-amplification in other Laeliinae species (Orchidaceae)

One of the most significant challenges confronting orchid researchers is the lack of specific molecular markers, mainly for species in the Neotropics. Here we report the first set of specific chloroplast microsatellite primers (cpSSR) developed for Neotropical orchids. In total, nine polymorphic cpSSR loci were isolated and characterized in four species occurring in the Brazilian Atlantic Rainforest: Epidendrumcinnabarinum, E. denticulatum, E. fulgens and E. puniceoluteum. Levels of intraspecific polymorphism were characterized using two populations for each species, with 13–20 individuals each. Allele numbers varied from two to three per locus, while the number of haplotypes ranged from three to six per species. Extensive differentiation among the taxa was detected. All markers were successfully cross-amplified in eight other different genera. These cpSSRs markers will enable novel insights into the evolution of this important Neotropical genus.

Chromosome characterization and variability in some Iridaceae from Northeastern Brazil

The chromosomes of 15 species of Iridaceae of the genera Alophia, Cipura, Eleutherine, Neomarica and Trimezia (subfamily Iridoideae) were examined after conventional Giemsa staining. The karyotypes of Alophia drummondii (2n = 14+1B, 28, 42 and 56), Cipura paludosa (2n = 14), C. xanthomelas (2n = 28) and Eleutherine bulbosa (2n = 12) were asymmetric; Neomarica candida, N. caerulea, N. humilis, N. glauca, N. gracilis, N. northiana and Neomarica sp. (2n = 18); N. cf. paradoxa (2n = 28), Trimezia fosteriana (2n = 52), T. martinicensis (2n = 54) and T. connata (2n = 82) were all generally symmetric. New diploid numbers of 2n = 56 for Alophia drummondii, 2n = 18 for N. candida, N. humilis, N. glauca, and N. gracilis, 2n = 28 for N. cf. paradoxa, and 2n = 82 for T. connata are reported. The karyotypic evolution of the studied species is discussed.

Cytogenetics of some species of native fruits from northeast Brazil

This work aimed to characterize the karyotype of six species of native fruits from Brazil through number and chromosome morphology analysis. The young root tips were pretreated with 8-hydroxiquinolin 0.002M, squashed in 45% acetic acid, and conventionally stained with Giemsa. All species showed symmetrical karyotype with small chromosomes and 0.6-2.5µm of length, mainly meta to sub-metacentric ones with one to two secondary visible constrictions in all species, except in Bromelia karatas in which it was not possible to identify the chromosome morphology or the presence of secondary constrictions. In Myrtaceae family, it had been observed a diploid chromosome supplement with 2n=98 in Psidium arboretum Vell. and 2n=44 in P. araca Raddi; 2n=50 in Bromelia karatas L.; in the Malvaceae, 2n=16 for Guazuma ulmifolia Lam.; in Sapindaceae, 2n=32 in Talisia esculenta Radlk. and, in Caricaceae, 2n=18 in Jaracatia spinosa (Aubl.) A. DC. All chromosome data presented in this work have been karyologically unpublished, except for T. esculenta which had previous reports confirmed. The species are potentially useful in breeding systems, and a heterozygosis inversion seems to be involved in the karyotype evolution of Guazuma ulmifolia.

New Alcamide and Anti-oxidant Activity of Pilosocereus gounellei A. Weber ex K. Schum. Bly. ex Rowl. (Cactaceae)

The Cactaceae family is composed by 124 genera and about 1438 species. Pilosocereus gounellei, popularly known in Brazil as xique-xique, is used in folk medicine to treat prostate inflammation, gastrointestinal and urinary diseases. The pioneering phytochemical study of P. gounellei was performed using column chromatography and HPLC, resulting in the isolation of 10 substances: pinostrobin (1), β-sitosterol (2), a mixture of sitosterol 3-O-β-d-glucopyranoside/stigmasterol 3-O-β-d-glucopyranoside (3a/3b), 132-hydroxyphaeophytin a (4), phaeophytin a (5), a mixture of β-sitosterol and stigmasterol (6a/6b), kaempferol (7), quercetin (8), 7′-ethoxy-trans-feruloyltyramine (mariannein, 9) and trans-feruloyl tyramine (10). Compound 9 is reported for the first time in the literature. The structural characterization of the compounds was performed by analyses of 1-D and 2-D NMR data. In addition, a phenolic and flavonol total content assay was carried out, and the anti-oxidant potential of P. gounellei was demonstrated.

A new Epidendrum (Laeliinae-Orchidaceae) from the Atlantic Forest of northeastern Brazil: Evidence from morphology and cytogenetics

A new epiphytic species, Epidendrum sanchezii, is described from northeastern Brazil. The new species grows in the montane Atlantic forest of the states of Ceará and Pernambuco. It belongs to the E. difforme complex and is morphologically similar to E. angustatum, but the new species differs because it has smaller flowers, 7-veined sepals, a lip with a cuspidate apex, and a column that is strongly sigmoid. A karyological description of the new species is presented, including the pattern of CMA/DAPI bands, and this is compared with E. campaccii. A key is provided to distinguish species of the E. difforme complex in northeastern Brazil.ResumoUma nova espécie epífita Epidendrum sanchezii é descrita para a região Nordeste do Brasil, para a Floresta Atlântica montana dos estados do Ceará e Pernambuco. Esta é relacionada ao complexo E. difforme, e é morfologicamente semelhante com E. angustatum, mas se diferencia por flores menores, sépalas com 7 vênulas, labelo com ápice cuspidado e coluna fortemente sigmóide. Adicionalmente é apresentada uma descrição cariológica da espécie nova, comparando-a com E. campaccii, incluindo o padrão de bandas CMA/DAPI e uma chave de identificação para as espécies relacionadas do Nordeste do Brasil.

Intrapopulational chromosome number variation in Zephyranthes sylvatica Baker (Amaryllidaceae: Hippeastreae) from Northeast Brazil

Zephyranthes Herb. is a taxonomically complex and cytologically variable group, with about 65 species of Neotropical distribution. Chromosome number variability in 32 individuals of a Zephyranthes sylvatica population from Northeast Brazil was investigated. Three cytotypes were found: 2n = 12 (one metacentric, four submetacentric and one acrocentric pairs), in 24 individuals; 2n = 12 + 1B, in five and three individuals with 2n = 18, a triploid cytotype. All diploid individuals showed chromosomes with polymorphism in pair one and two, while in triploids this polymorphism was observed in all chromosome triplets, generally with two homomorphic chromosomes and a higher or lower heteromorphic chromosome. All individuals had reticulated interfasic nucleus and a slightly asymmetric chromosome complement, with one metacentric chromosome pair and the others more submetacentric to acrocentric. These data confirm the cytological variability previously registered for the genus. Mechanisms involved in karyotypic evolution in this population are discussed.

Karyotype diversity and genome size variation in Neotropical Maxillariinae orchids

Orchidaceae is a widely distributed plant family with very diverse vegetative and floral morphology, and such variability is also reflected in their karyotypes. However, since only a low proportion of Orchidaceae has been analysed for chromosome data, greater diversity may await to be unveiled. Here we analyse both genome size (GS) and karyotype in two subtribes recently included in the broadened Maxillariinea to detect how much chromosome and GS variation there is in these groups and to evaluate which genome rearrangements are involved in the species evolution. To do so, the GS (14 species), the karyotype - based on chromosome number, heterochromatic banding and 5S and 45S rDNA localisation (18 species) - was characterised and analysed along with published data using phylogenetic approaches. The GS presented a high phylogenetic correlation and it was related to morphological groups in Bifrenaria (larger plants - higher GS). The two largest GS found among genera were caused by different mechanisms: polyploidy in Bifrenaria tyrianthina and accumulation of repetitive DNA in Scuticaria hadwenii. The chromosome number variability was caused mainly through descending dysploidy, and x=20 was estimated as the base chromosome number. Combining GS and karyotype data with molecular phylogeny, our data provide a more complete scenario of the karyotype evolution in Maxillariinae orchids, allowing us to suggest, besides dysploidy, that inversions and transposable elements as two mechanisms involved in the karyotype evolution. Such karyotype modifications could be associated with niche changes that occurred during species evolution.