Manejo en bancos de germoplasma: estrategia para la ruptura de dormición de semillas de leguminosas

La gestión de los bancos de germoplasma mediante la conservación de semillas se encuentra en ocasiones con dificultades técnicas que pueden llegar a hacer su tarea poco eficiente. Una de esas dificultades puede ser el llevar a cabo los ensayos de viabilidad de las semillas de forma que los resultados se acerquen lo más posible a la verdadera situación de los lotes estudiados. Este aspecto tiene especial importancia en aquellos casos en los que las semillas presentan dormición. Una característica de las semillas de especies de la familia Fabaceae es presentar cubiertas duras. En estos casos la estrategia a aplicar se basa en utilizar tratamientos de escarificación. Sin embargo, en ocasiones, la variabilidad dentro de un lote de semillas y entre lotes (por ejemplo distintas poblaciones de una misma especie) puede ser muy elevada. El objetivo de este trabajo fue estudiar la variabilidad de la dureza de las cubiertas seminales entre cuatro poblaciones de cada una de estas especies: Medicago polymorpha, Trifolium glomeratum y T. subterraneum. Estas especies presentan además semillas de muy pequeño tamaño que dificultan los tratamientos de escarificación. Se utilizaron diversos tratamientos de escarificación que incluían el lijado de las semillas y tratamientos térmicos (frío, calor o cambios bruscos de temperatura). Los mejores tratamientos variaron con las especies y se pudo determinar aquellos que dieron los mejores resultados en las cuatro poblaciones estudiadas, de forma que la germinación aumentó desde un 0-10 % de las semillas control a 84-100 % en las escarificadas. Mediante el equipo Texture Analyzer TAXTPLUS se midió la dureza de las semillas, en relación a su resistencia a la rotura. Se observó una gran variabilidad dentro de cada población y entre poblaciones. La contribución en la reducción de la dureza de las cubiertas del mejor tratamiento de escarificación varió entre especies y entre poblaciones. Se discute la utilidad del estudio previo de la dureza de las semillas para determinar el mejor tratamiento a emplear. Agradecimientos: Proyecto RF2012-00014-C02-0

O gênero Hypnea (Cystocloniaceae, Rhodophyta) no litoral do estado da Bahia, Brasil

A detailed morpho-anatomical study of the genus Hypnea from the state of Bahia is presented. Eight species have been recognized: H. cenomyce, H. cervicornis, H. cornuta, H. musciformis, H. nigrescens, H. platyclada, H. spinella and H. valentiae. An identification key, as well as descriptions, illustrations, comparisons with related taxa and maps of distribution in Bahia for each species, are presented.É apresentado um estudo morfoanatômico detalhado do gênero Hypnea no estado da Bahia. Foram reconhecidas oito espécies: H. cenomyce, H. cervicornis, H. cornuta, H. musciformis, H. nigrescens, H. platyclada, H. spinella e H. valentiae. É apresentada uma chave de identificação, além de descrições, ilustrações, comparações com táxons relacionados e mapas de distribuição na Bahia para cada espécie

Genetic diversity of Passiflora setacea in different regions of Bahia, Brazil, through SSR markers

Passiflora setacea DC. is a wild species of passion fruit popularly known as ‘maracujá-do-sono’ or ‘sururuca’. It has been recognized for its potential in passion fruit genetic improvement, due to its resistance to several phytopathogens. The purpose of this study was to evaluate the genetic diversity among and within wild populations of P. setacea DC. from different regions of Bahia state, Brazil, revealed by SSR markers. In this regard, 147 samples of plants were collected from 18 localities and six different identity territories in the state. Six pairs of primers were able to amplify polymorphic loci for all individuals. We performed principal coordinates analysis (PCoA) and molecular variance analysis (AMOVA) using Nei genetic distances between individuals of each locations. In addition, we performed two Bayesian analyzes, using Structure and Structurama softwares. High levels of genetic differentiation between populations were observed, as well as the absence of correlation between genetic and geographic distances using the Mantel test. The populations have moderate polymorphism and diverge into two groups: one including populations from the southwestern distribution range, while the other contains all other populations. The existence of two genetic groups was supported by both Bayesian analyses of genetic structure. These results indicate that these populations should be considered for conserving the diversity of P. setacea in germplasm banks, as well as the use in genetic improvement programs of passion fruit

Variação Cromossômica em Cactáceas

http://dx.doi.org/10.5902/2179460X13189The Cactaceae family has 1500-1800 species grouped into 4 subfamilies. Although the amount of cytogenetic studies have not yet cover a significant part of the family, some chromosomal aspects can be highlighted. Family presents basic number n = 11, with variations in ploidy in all four subfamilies, but in a limited number of genus. The phenomenon is more common in Opuntioideae, which presents pronounced vegetative reproduction. Similarly, other groups, many of polyploid also reproduce asexually. Some taxa may show interspecific variation, with different levels of ploidy. The karyotypes are symmetrical, showing little structural change in chromosomes that are small, in most cases not exceeding 3 micrometers. There are records of interspecific hybrids and even partially fertile intergeneric which denotes a reasonable homology of chromosomes, and in some polyploid high level of bivalent formation was detected.A família Cactaceae possui entre 1500-1800 espécies agrupadas em 4 subfamílias. Embora a quantidade de estudos citogenéticos não cubra ainda parte significativa da família, alguns aspectos cromossômicos podem ser destacados. A família apresenta número básico n = 11, com variações em ploidia em todas as quatro subfamílias, mas em um número limitado de gêneros. O fenômeno é mais comum em Opuntioideae, que apresenta reprodução vegetativa acentuada. Da mesma maneira, em outros grupos, muitos dos poliploides também reproduzem assexuadamente. Alguns táxons podem mostrar variação interespecífica, com diferentes ploidias. Os cariótipos são simétricos, denotando pouca alteração estrutural nos cromossomos que são pequenos, na maioria dos casos não excedendo 3μm. Existem registros de híbridos interespecíficos e mesmo intergenéricos parcialmente férteis o que denota uma razoável homologia dos cromossomos, e em alguns poliploides foi detectado alto nível de formação de bivalentes

Analysis Of The Ergosterol Biosynthesis Pathway Cloning, Molecular Characterization And Phylogeny Of Lanosterol 14 α-demethylase (erg11) Gene Of Moniliophthora Perniciosa.

The phytopathogenic fungus Moniliophthora perniciosa (Stahel) Aime & Philips-Mora, causal agent of witches' broom disease of cocoa, causes countless damage to cocoa production in Brazil. Molecular studies have attempted to identify genes that play important roles in fungal survival and virulence. In this study, sequences deposited in the M. perniciosa Genome Sequencing Project database were analyzed to identify potential biological targets. For the first time, the ergosterol biosynthetic pathway in M. perniciosa was studied and the lanosterol 14α-demethylase gene (ERG11) that encodes the main enzyme of this pathway and is a target for fungicides was cloned, characterized molecularly and its phylogeny analyzed. ERG11 genomic DNA and cDNA were characterized and sequence analysis of the ERG11 protein identified highly conserved domains typical of this enzyme, such as SRS1, SRS4, EXXR and the heme-binding region (HBR). Comparison of the protein sequences and phylogenetic analysis revealed that the M. perniciosa enzyme was most closely related to that of Coprinopsis cinerea.37683-9

Aspectos atuais da realização de testes moleculares para a doença de Huntington em centros de pesquisa e laboratórios brasileiros

Introdução: a doença de Huntington (DH) é uma enfermidade neurodegenerativa e de desenvolvimento tardio, autossômica dominante. Declínio cognitivo, coréia, disfunção motora severa e óbito no estágio final, são sintomas que caracterizam a doença. Atualmente, testes moleculares para diagnóstico pré-sintomático estão acessíveis à população em risco, porém implicações éticas permeiam esse tipo de exames. Objetivo: avaliar aspectos atuais da realização de testes genéticos para DH no Brasil por meio de estudo analítico de amostra de laboratórios. Metodologia: foram utilizados questionários semiestruturados enviados a 19 laboratórios que ofereciam testes diagnósticos e preditivos para a doença em suas paginas virtuais, por meio de correio eletrônico, a fim de obter informações sobre a metodologia empregada para os testes, infraestrutura, composição da equipe técnica, sexo dos indivíduos atendidos, percentagem de resultados positivos e cuidados oferecidos ao indivíduo/família antes e após a realização dos exames. Resultados: os laboratórios que aceitaram participar do estudo e responderam ao questionário informaram dispor de uma infraestrutura excelente, em termos de pessoal e equipamentos, atendendo aos requisitos básicos para a realização dos exames utilizando principalmente a técnica da Reação em Cadeia da Polimerase (PCR), na metodologia molecular. O percentual de resultado positivo para DH nos laboratórios pesquisados variou de 30 a 90%, sendo que este último percentual foi apresentado pelo laboratório vinculado a Instituto Público de Ensino Superior que era o único a oferecer acompanhamento psicológico e/ou psiquiátrico antes e após os exames. Conclusão: para promover a ampliação do acesso a esse tipo de teste à população acometida pela doença de Huntington, deve ser estimulada a criação de laboratórios com tecnologia de ponta e a formação de recursos humanos especializados

Dormancy breaking and germination of Adenocarpus desertorum, Astragalus gines-lopezii and Hippocrepis grosii (Fabaceae) seeds, three threatened endemic Spanish species

The effectiveness of different presowing treatments for removing hardseededness in Adenocarpus desertorum, Astragalus gines-lopezii and Hippocrepis grossi, three endemic and threatened perennial leguminous species of Spain, was evaluated. Untreated seeds of all three species were germinated over a range of constant (15, 20 and 25°C) and alternating temperatures (15/25 and 20/30°C) under a 16-hour light photoperiod. A considerable fraction of these seeds had physical dormancy caused by a water-impermeable seed coat. Germination was studied for seeds subjected to different presowing treatments: dry heat, hot water, ultra-low freezing, liquid nitrogen, freeze-thaw and mechanical scarification. The most effective method for promoting germination of Adenocarpus desertorum (two populations) and Astragalus gines-lopezii (two populations) was mechanical scarification with pliers. The highest germination percentages of H. grosii were reached by seeds mechanically scarified and also by seeds stored in an ultra-low freezer for 24 hours. Our data provided useful information in germination protocols for ex situ propagation of these three endemic and threatened species, being the first report on seed germination behaviour of Adenocarpus desertorum and Hippocrepis grosii

Coalescent-Based Species Delimitation in Herbaceous Bamboos (Bambusoideae, Olyreae) from Eastern Brazil: Implications for Taxonomy and Conservation in a Group with Weak Morphological Divergence Coupled with Low Genetic Diversity

Species delimitation in herbaceous bamboos has been complex and, in some genera, a great part of its diversity has been confirmed only based on genetic information, as is the case of the genus Raddia. It includes nine species, all occurring in Brazil, but only R. portoi predominates in dry forests of the Northeast associated with the Caatinga phytogeographic domain. This species is morphologically close to R. angustifolia, which is known for a single location in the Atlantic Forest in Southern Bahia, and is considered to be threatened by extinction. Besides problems with taxonomic focus, actions for its conservation are complicated because it is not certain if it must be considered an independent species or included in the more widespread R. portoi. In this study, we used coalescent multispecies (MSC) theory approaches combined with genetic structure analyses in an attempt to delimit these two species. Different analyses were congruent and the species delimitation using MSC inferred distinct lineages supporting their recognition as two species. These results solved the taxonomic doubts and also showed the power of these approaches to delimit species as lineages, even in groups with weak morphological divergence and low genetic variability, and also impacting our knowledge for conservation purposes