Genetic Diversity of Common Bean (Phaseolus vulgaris L.) Landraces Based on Morphological Traits and Molecular Markers.

The objective of this study was to evaluate the genetic diversity among traditional common bean accessions through morphological descriptors and molecular markers. Sixty-seven common bean accessions from the Germplasm bank of the Instituto Federal of Espírito Santo-Campus de Alegre were evaluated. For this, 25 specific morphological descriptors were used, namely 12 quantitative and 13 qualitative ones. A diversity analysis based on morphological descriptors was carried out using the Gower algorithm. For molecular characterization, 23 ISSR primers were used to estimate dissimilarity using the Jaccard Index. Based on the dendrograms obtained by the UPGMA method, for morphological and molecular characterization, high genetic variability was observed between the common bean genotypes studied, evidenced by cophenetic correlation values in the order of 0.99, indicating an accurate representation of the dissimilarity matrix by the UPGMA clustering. In the morphological characterization, high phenotypic diversity was observed between the accessions, with grains of different shapes, colors, and sizes, and the accessions were grouped into nine distinct groups. Molecular characterization was efficient in separating the genotypes in the Andean and Mesoamerican groups, with the 23 ISSR primers studied generating an average of 6.35 polymorphic bands. The work identified divergent accessions that can serve different market niches, which can be indicated as parents to form breeding programs in order to obtain progenies with high genetic variability.

Diversity of vegetable landraces in the Pampa biome of Brazil and Uruguay: utilization and conservation strategies.

The historical meeting between originally American people, European colonizers, and slaved peoples from Africa in the biome Pampa in South Brazil and Uruguay involved a cultural syncretism and a great genetic diversity of landraces of cultivated species. Genetic richness evolved by selection and cultural processes in response to different environments, cultural backgrounds, and needs. This review summarized the knowledge on vegetable and maize landraces in South Brazilian and Uruguayan Pampa biome, to design a strategy towards the rediscovery, conservation, and sustainable use. Landraces diversity maintained in situ and ex situ is described, specific case studies are presented, and the main problems and tools towards landraces re-valorization are discussed. We show that traditional family farming systems maintain diverse vegetable species, mainly squashes (Cucurbita spp.), sweet potato (Ipomoea batatas), beans (Phaseolus spp.), onion (Allium cepa), peppers (Capsicum spp.), tomato (Solanum lycopersicum), next to leafy vegetables and maize, among others. We propose the priority of systematic surveys as a basis for monitoring genetic erosion, increasing complementariness between in situ and ex situ conservation, and implementing sustainable conservation and utilization. The case studies highlight genetic diversity within each cultivated species, with different crop physiological responses; disease resistances, different quality traits and associated uses, from animal feeding in maize to a range of culinary uses linked to traditional culture in maize and vegetable species, and ornamental uses of specific Capsicum and Cucurbita. Some landraces were the basis for breeding, where improved cultivars allowed the competitiveness of landrace germplasm in the markets. Renewed industrialized products allowed the competitive and sustainable use of Capsicum landraces in Brazilian farmers communities. Strategies towards in situ conservation improvements and valorization are discussed; emphasizing the role played by agroecology, community seed banks and custodian farmers, participatory plant breeding, promotion of landraces specialties among consumers, and the need of research and capacity building, among others. Farmers' participation in the decisions is a key factor, along with the academia and the public sector. Landraces and associated knowledge are treasures to be used to benefit from farmers to consumers, directing the course of agriculture towards sustainable directions.

Chromosomic studies in Zephyranthes citrina baker (Amaryllidaceae), a polyploid ornamental / Estudios cromosómicos en Zephyranthes citrina baker (Amaryllidaceae), un poliploide ornamental

ABSTRACT Zephyranthes citrina is an ornamental American bulbous plant used as an ornamental garden crop for the aesthetic qualities of its yellow perigonium. The objective of this work was to characterize the species by classical chromosome staining and fluorochrome banding. A sporophytic chromosome number of 2n=8x=48 chromosomes was observed, being the karyotypic formula 20 m + 26 sm + 2 st. Satellites were detected in the short arm of metacentric chromosomes 8, 9, 11 and 12, which colocalized with constitutive heterochromatin CMA+/DAPI-/0 bands. The karyotype comprised chromosome pairs with terminal constitutive heterochromatin bands that included satellites and heteromorphic clusters indicating that it is an allooctoploid. These results will be used as a tool for monitoring genetic improvement, in interspecific crosses and its progenies and in biotechnological procedures by in vitro culture.

RESUMEN Zephyranhtes citrina es una planta bulbosa americana, ornamental, utilizada en jardines por las cualidades estéticas de su perigonio amarillo. El objetivo de este trabajo fue caracterizar citogenéticamente la especie con tinción clásica convencional y bandeo cromosómico. Se observó un número cromosómico esporofítico de 2n=8x=48, siendo la fórmula cariotípica 20 m + 26 sm + 2st. Se detectaron satélites en el brazo corto de los cromosomas metacéntricos 8, 9, 11 y 12, que co-localizaron con bandas de heterocromatina constitutiva CMA+/DAPI-. El cariotipo comprendió pares de cromosomas con bandas de heterocromatina constitutivas terminales que incluyeron satélites y grupos heteromórficos que indican que es un alooctoploide. Estos resultados serán usados como herramientas en el monitoreo del mejoramiento genético, en análisis de cruzamientos interespecíficos y progenies y en procedimientos biotecnológicos de cultivo in vitro.

Patterns of Traditional and Modern Uses of Wild Edible Native Plants of Chile: Challenges and Future Perspectives.

Wild Edible Plants (WEPs) still play a vital role in the subsistence of many traditional communities, while they are receiving increasing recognition in tackling food security and nutrition at the international level. This paper reviews the use patterns of native WEPs in Chile and discusses their role as future crops and sources of food products. We conducted an extensive literature review by assessing their taxonomic diversity, life forms, consumption and preparation methods, types of use (traditional and modern), and nutritional properties. We found that 330 native species were documented as food plants, which represent 7.8% of the total flora of Chile. These species belong to 196 genera and 84 families. The most diverse families are Asteraceae (34), Cactaceae (21), Fabaceae (21), Solanaceae (20) and Apiaceae (19), and the richest genera in terms of number of species are Solanum (9), Ribes (8), Berberis (7), Hypochaeris (7) and Oxalis (6). Perennial herbs are the predominant life form (40%), followed by shrubs (35%), trees (14%), and annual and biannual herbs (11%). Fruits (35.8%), roots (21.5%) and leaves (20.0%) are the parts of plants consumed the most. Nine different food preparation categories were identified, with 'raw' forming the largest group (43%), followed by 'beverages' (27%), 'savoury preparations' (27%), and 'sweet' (13%). Almost all native Chilean WEPs have reported traditional food uses, while only a few of them have contemporary uses, with food products mainly sold in local and specialised markets. Species' richness, taxonomic diversity and family representation have similar patterns to those observed for the world flora and other countries where surveys have been carried out. Some Chilean native WEPs have the potential to become new crops and important sources of nutritious and healthy products in the food industry. However, there are still many gaps in knowledge about their nutritional, anti-nutritional and biochemical characteristics; future research is recommended to unveil their properties and potential uses in agriculture and the food industry.

Crop genetic erosion: understanding and responding to loss of crop diversity.

Crop diversity underpins the productivity, resilience and adaptive capacity of agriculture. Loss of this diversity, termed crop genetic erosion, is therefore concerning. While alarms regarding evident declines in crop diversity have been raised for over a century, the magnitude, trajectory, drivers and significance of these losses remain insufficiently understood. We outline the various definitions, measurements, scales and sources of information on crop genetic erosion. We then provide a synthesis of evidence regarding changes in the diversity of traditional crop landraces on farms, modern crop cultivars in agriculture, crop wild relatives in their natural habitats and crop genetic resources held in conservation repositories. This evidence indicates that marked losses, but also maintenance and increases in diversity, have occurred in all these contexts, the extent depending on species, taxonomic and geographic scale, and region, as well as analytical approach. We discuss steps needed to further advance knowledge around the agricultural and societal significance, as well as conservation implications, of crop genetic erosion. Finally, we propose actions to mitigate, stem and reverse further losses of crop diversity.

Seed longevity of maize conserved under germplasm bank conditions for up to 60 years.

BACKGROUND AND AIMS: The long-term conservation of seeds of plant genetic resources is of key importance for food security and preservation of agrobiodiversity. Nevertheless, there is scarce information available about seed longevity of many crops under germplasm bank conditions. METHODS: Through germination experiments as well as the analysis of historical monitoring data, we studied the decline in viability manifested by 1000 maize (Zea mays subsp. mays) seed accessions conserved for an average of 48 years at the CIMMYT germplasm bank, the largest maize seedbank in the world, under two cold storage conditions: an active (-3 °C; intended for seed distribution) and a base conservation chamber (-15 °C; for long-term conservation). KEY RESULTS: Seed lots stored in the active chamber had a significantly lower and more variable seed germination, averaging 81.4 %, as compared with the seed lots conserved in the base chamber, averaging 92.1 %. The average seed viability detected in this study was higher in comparison with that found in other seed longevity studies on maize conserved under similar conditions. A significant difference was detected in seed germination and longevity estimates (e.g. p85 and p50) among accessions. Correlating seed longevity with seed traits and passport data, grain type showed the strongest correlation, with flint varieties being longer lived than floury and dent types. CONCLUSIONS: The more rapid loss of seed viability detected in the active chamber suggests that the seed conservation approach, based on the storage of the same seed accessions in two chambers with different temperatures, might be counterproductive for overall long-term conservation and that base conditions should be applied in both. The significant differences detected in seed longevity among accessions underscores that different viability monitoring and regeneration intervals should be applied to groups of accessions showing different longevity profiles.

Genetic variation for tolerance to the downy mildew pathogen Peronospora variabilis in genetic resources of quinoa (Chenopodium quinoa).

BACKGROUND: Quinoa (Chenopodium quinoa Willd.) is an ancient grain crop that is tolerant to abiotic stress and has favorable nutritional properties. Downy mildew is the main disease of quinoa and is caused by infections of the biotrophic oomycete Peronospora variabilis Gaüm. Since the disease causes major yield losses, identifying sources of downy mildew tolerance in genetic resources and understanding its genetic basis are important goals in quinoa breeding. RESULTS: We infected 132 South American genotypes, three Danish cultivars and the weedy relative C. album with a single isolate of P. variabilis under greenhouse conditions and observed a large variation in disease traits like severity of infection, which ranged from 5 to 83%. Linear mixed models revealed a significant effect of genotypes on disease traits with high heritabilities (0.72 to 0.81). Factors like altitude at site of origin or seed saponin content did not correlate with mildew tolerance, but stomatal width was weakly correlated with severity of infection. Despite the strong genotypic effects on mildew tolerance, genome-wide association mapping with 88 genotypes failed to identify significant marker-trait associations indicating a polygenic architecture of mildew tolerance. CONCLUSIONS: The strong genetic effects on mildew tolerance allow to identify genetic resources, which are valuable sources of resistance in future quinoa breeding.

Climatic adaptation and ecological descriptors of wild beans from Mexico.

Despite its economic, social, biological, and cultural importance, wild forms of the genus Phaseolus are not well represented in germplasm banks, and they are at great risk due to changes in land use as well as climate change. To improve our understanding of the potential geographical distribution of wild beans (Phaseolus spp.) from Mexico and support in situ and ex situ conservation programs, we determined the climatic adaptation ranges of 29 species and two subspecies of Phaseolus collected throughout Mexico. Based on five biotic and 117 abiotic variables obtained from different databases-WorldClim, Global-Aridity, and Global-PET-we performed principal component and cluster analyses. Germplasm was distributed among 12 climatic types from a possible 28. The general climatic ranges were as follows: 8-3,083 m above sea level; 12.07-26.96°C annual mean temperature; 10.33-202.68 mm annual precipitation; 9.33-16.56 W/m2 of net radiation; 11.68-14.23 hr photoperiod; 0.06-1.57 aridity index; and 10-1,728 mm/month of annual potential evapotranspiration. Most descriptive variables (25) clustered species into two groups: One included germplasm from semihot climates, and the other included germplasm from temperate climates. Species clustering showed 45% to 54% coincidence with species previously grouped using molecular data. The species P. filiformis, P. purpusii, and P. maculatus were found at low-humidity locations; these species could be used to improve our understanding of the extreme aridity adaptation mechanisms used by wild beans to avoid or tolerate climate change as well as to introgress favorable alleles into new cultivars adapted to hot, dry environments.

La diversidad genética y la variabilidad genética: dos conceptos diferentes asociados al germoplasma y al mejoramiento genético vegetal / Genetic diversity and genetic variability: two different concepts associated to plant germplasm and breeding

En este trabajo se diferencian a los recursos fitogenéticos in situ y ex situ para protección y conservación, de aquellos recursos que colecciona, mantiene y utiliza el hombre para su subsistencia desarrollando variedades cultivadas obtenidas por cualquier método de selección artificial. La imprecisión, confusión y distorsión encontradas en muchos trabajos relacionados al tema aquí planteado, con respecto a la terminología, su significado, sus alcances y sus consecuencias, motivaron el desarrollo de este trabajo de opinión. En mejoramiento, las colecciones de trabajo son utilizadas como una fuente de variabilidad y adaptación. En ese proceso de obtención de cultivares, indefectiblemente, se utiliza sólo una parte de la variabilidad genética del inicio, que se restringe en cada ciclo selectivo. La confusión mencionada con respecto a la pérdida de variabilidad genética se debe a que las mayores probabilidades de éxito en un programa de mejoramiento estarán asociadas a la disponibilidad de una amplia variabilidad genética en la colección de trabajo base del mejoramiento y no en el cultivar obtenido. La diversidad genética se conserva y protege en otro ámbito y con otras disciplinas. La variabilidad genética se re-utiliza y elimina selectivamente para obtener nuevos cultivares en los procesos de selección artificial. El hombre, al obtener variedades primitivas o nuevos cultivares modernos, siempre perdió variabilidad genética con respecto a la población que le dio origen, como consecuencia del mismo proceso selectivo. Ante ese contexto, respetando la biodiversidad, se puede mantener la productividad agrícola a largo plazo con el aporte concreto del mejoramiento genético.

This paper differentiates plant genetic resources maintained in situ and ex situ for protection and conservation, from those resources that man collects, maintains and uses for his subsistence by developing cultivated varieties through any artificial selection method. The imprecision, confusion and distortion found in many papers related to the issue raised here with respect to terminology, its meaning, its scope and its consequences, motivated the development of this opinion work. In plant breeding working collections are used as a source of variability and adaptation. In this process, unfailingly, only a part of the genetic variability is used, which is restricted in each selective cycle since the purpose of this process is to obtain new cultivars. In the selection process there is always a loss of genetic variability with respect to the population that gave rise to it. The confusion mentioned with respect to the loss of genetic variability resides in the following: the greater probabilities of success in a plant breeding program will be associated to the availability of a wide genetic variability in the starting elite collection and not in the obtained cultivar. One of the reiterated concepts attributes the loss of genetic variability to the advent of new cultivars and the narrow genetic base that they represent. The loss of genetic variability is a consequence of the achievement of genetic progress in plant breeding. In this context, the respect for diversity in protected areas and agrobiodiversity in agricultural areas, is the way for producing profitable yields while maintaining the long-term productivity as a result of the implementation of plant breeding.

Increasing homogeneity in global food supplies and the implications for food security.

The narrowing of diversity in crop species contributing to the world's food supplies has been considered a potential threat to food security. However, changes in this diversity have not been quantified globally. We assess trends over the past 50 y in the richness, abundance, and composition of crop species in national food supplies worldwide. Over this period, national per capita food supplies expanded in total quantities of food calories, protein, fat, and weight, with increased proportions of those quantities sourcing from energy-dense foods. At the same time the number of measured crop commodities contributing to national food supplies increased, the relative contribution of these commodities within these supplies became more even, and the dominance of the most significant commodities decreased. As a consequence, national food supplies worldwide became more similar in composition, correlated particularly with an increased supply of a number of globally important cereal and oil crops, and a decline of other cereal, oil, and starchy root species. The increase in homogeneity worldwide portends the establishment of a global standard food supply, which is relatively species-rich in regard to measured crops at the national level, but species-poor globally. These changes in food supplies heighten interdependence among countries in regard to availability and access to these food sources and the genetic resources supporting their production, and give further urgency to nutrition development priorities aimed at bolstering food security.

Teor e composição do óleo essencial de quatro acessos e duas cultivares de manjericão (Ocimum basilicum L. ) / Essential oil composition and content of different accessions and cultivars of basil (Ocimum basilicum L. )

O objetivo desse estudo foi avaliar o teor e a composição química dos óleos essenciais de quatro acessos silvestres de manjericão (Ocimum basilicum L.), provenientes de diferentes regiões geográficas, e duas cultivares comerciais cultivados sob as mesmas condições edafoclimáticas. As sementes dos acessos foram coletadas nos município de Gurupi-TO (GUR) e de Monte Alegre-GO (MAL, MVE e FPS) e as sementes da cultivar comercial manjericão roxo (MR) foram adquiridas no comércio de Gurupi e da cultivar Maria Bonita (MB) foram fornecidas pelo Horto de Plantas Medicinais da Universidade Federal de Lavras. O plantio foi realizado em vasos com capacidade de dez litros utilizando-se como substrato: solo de barranco e esterco bovino na proporção 2:1. O óleo essencial foi obtido por hidrodestilação em aparelho tipo Clevenger e a identificação e a porcentagem relativa dos compostos do óleo essencial foi realizada por Cromatografia à Gás acoplada a Detector de Espectrometria de Massas. Foram identificados trinta e nove substâncias nos óleos essenciais obtidos, abrangendo monoterpenos, sesquiterpenos e fenilpropanoides. Nas cultivares MB e MR o composto majoritário foi o linalol, enquanto nos acessos silvestres (MAL, GUR, FPS e MVE) o composto em maior quantidade foi o (E)-cinamato de metila. O maior teor de óleo essencial foi obtido na cultivar Maria Bonita (3,77%).

The objective of this study was to evaluate the essential oil chemical composition and content of four wild accessions of basil (Ocimum basilicum L.), from different geographical regions, and two commercial cultivars grown under the same edaphoclimatic conditions. The seeds of the accessions were collected in the municipality of Gurupi, state of Tocantins (GUR), and Monte Alegre, state ofGoiás (MAL, MVE and FPS), and the seeds of the commercial cultivar of purple basil (MR) were acquired in the Gurupi market and the seeds of the commercial cultivar Maria Bonita (MB) were provided by the Garden of Medicinal Plants of the Federal University of Lavras. The seeds were planted in pots with a capacity of ten liters using as substrate soil from earth works and cattle manure in the proportion of 2:1. The essential oil was obtained by hydrodistillation using a Clevenger-type apparatus, and the identification and the relative percentage of the compounds of the essential oil were performed by Gas Chromatography coupled to Mass Spectrometry Detector. Thirty-nine compounds were identified in the essential oils obtained, which were divided into monoterpenes, sesquiterpenes and phenylpropanoids. In the cultivars MB and MR, the major compound was linalool, and in the wild accessions (MAL, GUR, FPS and MVE) it was the (E)-methyl cinnamate. The highest content of essential oil was obtained from the cultivar Maria Bonita (3.77%).

Diversidad y dittribución de las passifloraceae en el departamento del huila en Colombia / Diversity and Distribution of Passifloraceae in the Department of Huila in Colombia

Colombia es el país con mayor diversidad de Passifloraceae con 170 especies reportadas, tanto en formas silvestres como cultivadas. Sin embargo, existen zonas en el país donde esta riqueza ha sido poco explorada, como el departamento del Huila en el suroriente de la zona andina. Por esta razón, se revisaron las listas de inventarios con el objetivo de actualizar y establecer la distribución espacial de las especies en esta región con base en registros de herbario, literatura y datos de campo, para proponer estrategias de conservación. Un total de 26 especies pertenecientes al género Passiflora L. son registradas en el Huila entre los 1500 y 2500 msnm. Ocho de las especies son cultivadas y las otras 18 silvestres, se localizan principalmente en bordes de caminos y bosques secundarios. El bajo número de registros y de especies presentes en este departamento es el reflejo de la carencia de iniciativas de investigación sobre la biodiversidad florística. Lo anterior sugiere que esta región puede ser el escenario de muchas especies desconocidas en zonas poco o no exploradas. Por esta razón, la conservación in situ y de sus hábitats es una tarea urgente, al igual que la caracterización y evaluación de los recursos genéticos, lo que permitirá conocer los atributos de las especies silvestres y cultivadas para un mejor uso de la biodiversidad.

Colombia is the country with the greatest Passifloraceae diversity with 170 reported species of both wild and cultivated forms. However, there are areas in the country where this wealth has slightly been explored such as the department of Huila in the South East of the Andes. For this reason, inventory lists were reviewed in order to update and establish the spatial distribution of the species in this region based on herbarium records, literature and field data, and propose conservation strategies. A total of 26 species belonging to the genus Passiflora L. are recorded in Huila between 1500 and 2500 masl. Eight species are cultivated and the others 18 that are wild are found mainly along roadsides and in secondary forests. The low number of species records in this department reflects the lack of research initiatives on floristic biodiversity. This suggests that this region may harbor many unknown species in little or unexplored areas. For this reason, conservation of these species and their habitat is an urgent task, as well as the characterization and evaluation of these genetic resources.

A method for seedling recovery in Jatropha curcas after cryogenic exposure of the seeds

Actually, the germplasm of Jatropha spp. is conserved as whole plants in field collections. Under this storage method, the genetic resources are exposed to disease, pest and natural hazards such as human error, drought and weather damage. Besides, field genebanks are costly to maintain and with important requirements of trained personnel. Thus, the development of efficient techniques to ensure its safe conservation and regeneration is therefore of paramount importance. In this work we describe a method for Jatropha curcas seeds cryoexposure and seedling recovery after thawed. In a first experiment, an efficient protocol for in vitro plant recovery was carried out using zygotic embryo or seeds with or without coat. In a second experiment, desiccated seeds with or without coat were exposed to liquid nitrogen and evaluated after cryoexposure. Germination percentages were variable among treatments, and seeds demonstrated tolerance to liquid nitrogen exposure under certain conditions. Seeds of J. curcas presented up to 99.6% germination after seed coat removal. Seeds with coat cultured in vitro did not germinate, and were 60% contaminated. The germination of the zygotic embryos was significantly higher in the ½ MS medium (93.1%) than in WPM medium (76.2%), but from zygotic embryo, abnormal seedlings reached up to 99%. Seeds with coat exposed to liquid nitrogen showed 60% germination in culture after coat removal with good plant growth, and seeds cryopreserved without coat presented 82% germination, but seedlings showed a reduced vigor and a significant increase in abnormal plants. Seeds cultured in vitro with coat did not germinate, independently of cryoexposure or not. This study reports the first successful in vitro seedling recovery methodology for Jatropha curcas seeds, after a cryopreservation treatment, and is recommended as an efficient procedure for in vitro plant recovery, when seeds are conserved in germplasm banks by low or cryotemperatures.

Actualmente, el germoplasma de las especies de Jatropha ssp. se conserva como plantas enteras en las colecciones de campo. Bajo este método de almacenamiento, los recursos genéticos están expuestos a enfermedades, plagas y desastres naturales tales como el error humano, la sequía y las inclemencias del tiempo. Además, los bancos de germoplasma de campo son costosos de mantener y requieren bastante personal capacitado. Por lo tanto, el desarrollo de técnicas eficientes para asegurar su conservación segura así como su regeneración, es de suma importancia. En este trabajo se describe un método de recuperación para semillas y plántulas crioexpuestas de Jatropha curcas después de descongeladas. En un primer experimento, se llevó a cabo un protocolo eficiente para la recuperación de plantas in vitro mediante el uso de embriones cigóticos o semillas con o sin testa. En un segundo experimento, las semillas disecadas, con o sin testa fueron expuestas a nitrógeno líquido y se evaluaron después de la crioexposición. Los porcentajes de germinación fueron variables entre los tratamientos, y las semillas demostraron tolerancia a la exposición del nitrógeno líquido bajo ciertas condiciones. Las semillas de J. curcas presentaron hasta un 99.6% de germinación después de la eliminación de la testa. Las semillas con la testa cultivadas in vitro no germinaron, y el 60% se contaminaron. La germinación de los embriones cigóticos fue significativamente alta en el medio ½ MS (93.1%) en comparación con el medio WPM (76.2%), pero desde los embriones zigóticos, las plántulas anormales alcanzaron más del 99%. Semillas con la testa inmersa en nitrógeno líquido mostraron un 60% de germinacion en cultivos despúes de la remoción de la testa con un buen crecimiento de la planta, y las semillas criopreservadas sin testa presentaron un 82% de germinación, pero las plántulas mostraron un reducido vigor y un incremento significativo de plantas anormales. Semillas con testa cultivadas in vitro no germinaron, independientemente de la criopreservación o no. Este estudio reporta el primer éxito in vitro de una metodología de recuperación de plántulas para semillas de Jatropha curcas, después de un tratamiento de criopreservación, que se recomienda como un procedimiento eficaz para la recuperación de plantas in vitro, cuando las semillas se conservan en bancos de germoplasma a bajas o crio-temperaturas.

Estudo da divergência genética por características morfológicas entre acessos de mentrasto (Ageratum conyzoides L. ) coletados no estado do Tocantins em diferentes épocas / Genetic divergence study by morphologic traits among mentrasto (Ageratum conyzoides L. ) accessions collected in the state of Tocantins in different period

Este trabalho objetivou avaliar a divergência genética entre nove acessos de mentrasto (Ageratum conyzoides) por métodos multivariados utilizando caracteres morfológicos, em quatro épocas de colheita. Os nove acessos de mentrasto foram obtidos de plantas que ocorrem naturalmente nas cinco regiões climáticas do Estado do Tocantins. Em cada época de colheita foram avaliadas as características como biomassa fresca da parte aérea, biomassa seca, área foliar, número de folhas, floração e altura. Pela análise de agrupamento (método de Tocher) foram formados dois grupos na primeira e quarta épocas de colheita, três grupos na segunda época e quatro grupos na terceira época de colheita. Observou-se variação na constituição dos grupos pelos acessos nas épocas de colheita. A divergência genética entre acessos de mentrasto, avaliada por caracteres morfológicos, foi influenciada pelo estádio de desenvolvimento da espécie. A existência de variabilidade entre os acessos coletados em diferentes localidades fornece subsídio para a coleta sistematizada de germoplasma em A. conyzoides no Estado do Tocantins.

This study aimed to analyze the genetic divergence among nine mentrasto (Ageratum conyzoides) accessions by multivariate methods using morphologic traits for four harvesting periods. The nine accessions of mentrasto were obtained from plants that occur naturally in five climatic regions of the state of Tocantins. At each harvesting period, the following traits were evaluated: fresh biomass of the aerial part, dry biomass, leaf area, number of leaves, flowering and height. The grouping analysis (Tocher's method) identified two groups, in the first and fourth harvest periods, three groups in the second harvest period and four groups in the third harvest period. Variation was observed for the group constitutions among the different harvesting periods. The genetic divergence among mentrasto accessions, evaluated by morphologic traits, was influenced by developmental stage of specie. The existence of genetic variability among accessions from different regions supports the systematic collection of A. conyzoides germplasm in the state of Tocantins.