ABSTRACT. Macrophomina phaseolina (Tassi) Goid is the causal agent of charcoal rot and vine decline in cucurbits such as watermelon. Molecular methods have been used for rapid identification. However, a large number of steps used reduces its applicability. This study aimed to detect M. phaseolina in watermelon from producing areas in Northeastern Brazil by direct PCR. Plant tissue samples were collected from seven producing areas and the DNA was extracted using the CTAB method. Amplifications were performed by direct PCR using the MpKFI/MpKRI primers, then the PCR products were subjected to agarose gel electrophoresis and sequenced. Amplicons of 350 bp were observed in stem tissue samples from three areas. The identity of the samples was confirmed by sequencing. This study represents the first molecular diagnosis of M. phaseolina associated with watermelon in Northeastern Brazil. The methodology presented here can be applied for a reliable and simple diagnosis of the pathogen in other crops.

RESUMO A manga (Mangifera indica L.) é uma fruta tropical de grande importância no mundo. No entanto, as perdas pós-colheita dos frutos são causadas pela antracnose, doença causada principalmente por fungos fitopatogênicos do gênero Colletotrichum. Assim, este trabalho teve como objetivo estudar a morfologia, similaridade genética e patogenicidade de isolados de Colletotrichum spp. de manga no estado do Rio Grande do Norte, Brasil. A avaliação morfológica de 28 isolados, com base na cor da colônia, tamanho dos conídios e apressórios e taxa de crescimento, mostrou que os isolados pertencem à espécie C. gloeosporioides. Posteriormente, foi confirmado com oligonucleotídeos específicos para a espécie. Além disso, a avaliação combinada com RAPD (Random Amplified Polymorphic DNA) e ISSR (Inter Simple Sequence Repeats) mostrou uma similaridade genética de 0,23 entre os Isolados 12 e 21, e 0,71 entre os Isolados 2 e 4, um indicativo de alta variabilidade entre os isolados, com dissimilaridade acima de 75%. Além disso, o dendrograma gerado pelo método UPGMA indicou que os isolados foram dispostos em oito grupos, os quais não se correlacionaram com o local de coleta. Com base na patogenicidade, embora a maioria dos isolados tenha apresentado baixa virulência para a cultivar Tommy Atkins, alguns deles se mostraram altamente agressivos (Isolados 9, 15, 20, 21, 24, 26 e 27). Além disso, a patogenicidade não se correlacionou com os aglomerados. Concluindo, os resultados revelaram alta variabilidade genética e patogênica em C. gloeosporioides isolado de cultivares de manga em uma das principais regiões exportadoras do Brasil.

ABSTRACT Mango (Mangifera indica L.) is a tropical fruit of great importance in the world. However, fruit postharvest losses are caused by anthracnose, a disease caused mainly by phytopathogenic fungi from the Colletotrichum genus. Thus, this work aimed to study morphology, genetic similarity, and pathogenicity of Colletotrichum spp. isolates from mango in Rio Grande do Norte state, Brazil. Morphological evaluation of 28 isolates, based on colony color, size of conidia and appressoria, and growth rate, showed that the isolates belong to the C. gloeosporioides species. It was later confirmed with species-specific oligonucleotides. Also, combined evaluation with RAPD (Random Amplified Polymorphic DNA) and ISSR (Inter Simple Sequence Repeats) showed a genetic similarity of 0.23 between Isolates 12 and 21, and 0.71 between Isolates 2 and 4, an indication of high variability among isolates, with dissimilarity over 75%. Moreover, the dendrogram generated by the UPGMA method indicated that the isolates were arranged in eight groups, which did not correlate with the collection site. Based on pathogenicity, although most isolates showed low virulence for Tommy Atkins cultivar, some of them proved to be highly aggressive (Isolates 9, 15, 20, 21, 24, 26, and 27). Also, pathogenicity did not correlate with clusters. In conclusion, the results revealed high genetic and pathogenic variability in C. gloeosporioides isolated from mango cultivars in one of the main exporting regions in Brazil.

Abstract: Background and Aims: Cashew (Anacardium occidentale) is a native Brazilian tree, cultivated in various warm climates across the world. The cashew kernels production has been an important economic activity for many tropical countries, providing a variety of food with great nutrition value. The genetic diversity among the early dwarf cultivars used to production is poorly understood, as is the nutritional composition among nuts from those plants. This work aimed to evaluate the physicochemical characteristics of cashew kernels and to study genetic diversity among twelve cultivars to indicate superior genotypes for future breeding programs. Methods: Cashew kernels from twelve cultivars were evaluated for pH, titratable acidity, moisture, ash, lipids and proteins. The genetic variability was assessed using RAPD and ISSR molecular markers. Data from molecular and physicochemical analyses were used to estimate the genetic distances and Mantel test approach was applied to calculate Pearson’s correlation between the data. Key results: A high genetic variability was found among the cultivars. BRS 274 and BRS 275 were the closest genetically, while CCP 09 and BRS 189 were the most distant ones. On the other hand, EMBRAPA 51 and BRS 226 showed cashew kernels with more similar physicochemical characteristics, while BRS 189 and BRS 253 had the more different ones. Moreover, no correlation was found between the physicochemical and molecular results. Cashew kernels had pH close to neutrality, low acidity, considerable moisture content, and high lipid and protein contents. Conclusions: The cashew kernels from the cultivars studied here had low acidity and pH, considerable moisture and ash contents, and high protein and lipid contents. BRS 189, BRS 253, and CCP 1001 showed the best values for proteins, lipids, acidity, and pH. In addition, those cultivars have maximum distance genetic among them, which can be used as parents in future gene combinations in breeding programs.

Resumen: Antecedentes y Objetivos: El marañón (Anacardium occidentale) es un árbol nativo de Brasil y cultivado en varios climas cálidos en todo el mundo. La producción de nueces de marañón ha sido una actividad económica importante para muchos países tropicales, proporcionando una variedad de alimentos con un gran valor nutricional. La diversidad genética entre los primeros árboles de marañón enanos utilizados para la producción es poco conocida, así como la composición nutricional entre los frutos secos de estas plantas. Este trabajo tuvo como objetivo evaluar las características fisicoquímicas de los granos de marañón y estudiar la diversidad genética entre doce cultivares para indicar genotipos superiores para futuros programas de mejoramiento. Métodos: Se evaluó el pH, acidez titulable, humedad, ceniza, lípidos y proteínas de los granos de marañón de doce cultivares. La variabilidad genética se evaluó mediante marcadores moleculares RAPD e ISSR. Se utilizaron datos de análisis moleculares y fisicoquímicos para estimar las distancias genéticas y se aplicó el método de prueba de Mantel para calcular la correlación de Pearson entre los datos. Resultados clave: Se encontró una alta variabilidad genética entre los cultivares. BRS 274 y BRS 275 fueron los más cercanos genéticamente, mientras que CCP 09 y BRS 189 fueron los más distantes. Por otro lado, EMBRAPA 51 y BRS 226 mostraron granos con características fisicoquímicas más similares, mientras que BRS 189 y BRS 253 tuvieron los más diferentes. Además, no se encontró correlación entre los resultados fisicoquímicos y moleculares. Los granos de marañón tenían un pH cercano a la neutralidad, baja acidez, considerable contenido de humedad y alto contenido de lípidos y proteínas. Conclusiones: Los granos de marañón de los doce cultivares estudiados aquí tenían baja acidez y pH, contenido considerable de humedad y cenizas, y alto contenido de proteínas y lípidos. BRS 189, BRS 253 y CCP 1001 mostraron los mejores valores de proteínas, lípidos, acidez y pH. Además, esos cultivares tienen una distancia genética máxima entre ellos, que pueden usarse como progenitores en futuras combinaciones de genes en programas de mejoramiento genético.

RESUMO Macrophomina pseudophaseolina foi recentemente relatada em áreas produtoras de melão em associação com plantas daninhas na região Nordeste. Espécies do gênero são agentes da podridão radicular e declínio das ramas (PRDR) do meloeiro, doença que reduz sua produtividade. O conhecimento da diversidade genética do patógeno é importante no desenvolvimento de métodos de controle eficientes. Nesse contexto, o objetivo desse trabalho foi analisar a variabilidade genética de isolados de M. pseudophaseolina coletados das plantas daninhas Trianthema portulacastrum L. e Boerhavia diffusa L. por meio dos marcadores moleculares ISSR e RAPD. Para isto, 41 isolados de M. pseudophaseolina foram submetidos à amplificação com cinco iniciadores ISSR e dez RAPD. A similaridade genética foi analisada através do coeficiente de Jaccard e o agrupamento obtido com o método UPGMA. Com a combinação dos dados dos marcadores os 41 isolados foram agrupados em 8 grupos principais. Não foi observado, para grande maioria dos grupos gerados, a relação do agrupamento de acordo com hospedeiro ou local de coleta. A similaridade genética entre os isolados variou de 0,15 a 0,87. A maior dissimilaridade genética (85%) foi observada entre o isolado MpBr11, coletado de T. portulacastrum no município de Icapuí/CE, do isolado MpBr65, coletado de B. diffusa em Assú/RN. Estas informações podem ser úteis para auxiliar programas de melhoramento genético na seleção de fontes de resistência e/ou em testes de métodos de controle contra PRDR do melão.

ABSTRACT Macrophomina pseudophaseolina has recently been reported in association with weeds in melon producing areas in Northeastern Brazil. Species from this genus are the causal agents of root rot and vine decline (RRVD) in melon, reducing its productivity. It is needed to know the genetic variability of the pathogen to develop effective control methods. Thus, this work aimed to assess the genetic diversity among M. pseudophaseolina isolates collected from the weeds Trianthema portulacastrum L. and Boerhavia diffusa L. using ISSR and RAPD markers. For this, 41 M. pseudophaseolina isolates were submitted to amplification with five ISSR and ten RAPD primers. Genetic similarity was analyzed using the Jaccard’s coefficient and cluster analysis was performed by the UPGMA method. Combining data from both markers, the 41 isolates were separated into eight groups. Most groups were not arranged according to geographical origin and host of the pathogen. The genetic similarity among isolates ranged from 0.15 to 0.87. On the other hand, the highest genetic dissimilarity (85%) was observed between the isolate MpBr11, collected from T. portulacastrum in Icapuí (CE), and MpBr65, collected from B. diffusa in Assú (RN). Results obtained herein can assist breeding programs for the selection of resistance sources and the development of effective control methods against RRVD in melon.