Genetic divergence in snap bean based on agronomic traits and resistance to bacterial wilt

The objectives of this research were to estimate the genetic divergence among genotypes of bush snap beanwith based on morphoagronomic descriptors and evaluation of resistance to bacterial wilt; to determine the relative importanceof the distinguishing traits of genotypes and to indicate potential parents to establish a snap bean breeding program forresistance to bacterial wilt. Two experiments were conducted, the first in the field and the second in a greenhouse, both with 15genotypes in a randomized block design with three replications. Seven traits were studied in the field experiment: days toflowering; days to harvest; mean pod length; number of pods; number of pods per plant; total pod weight and number of seedsper pod. In the greenhouse, the reaction of bacterial wilt was assessed based on two variables, one based on a descriptivegrade scale and the other based on the Area Under the Disease Progress Curve (AUDPC). For the evaluation of genotyperesistance to bacterial wilt the isolate Feij – 2634 of Curtobacterium flaccumfaciens pv. flaccumfaciens was inoculated. Thestatistics of pseudo t2 indicated the formation of four groups by the UPGMA method, the same number of groups as indicatedby the use of canonical variables. The traits that contributed most to genetic divergence were days to harvest, pod length, poddiameter and AUDPC

Agrobiodiversity in Cucurbita spp. landraces collected in Rio de Janeiro assessed by molecular markers

Diversity and genetic relationship in forty landraces of Cucurbita spp. collected at small farms in Rio de Janeiro, Brazil, were analyzed by RAPD and ISSR markers, using 20 and 15 primers, respectively. Both markers were efficient to cluster the accessions separating among species, but not so much to the detection of intra-specific variability, considering the event of different pairs of accessions comprising null genetic distances observed for both markers in C. moschata. Low values observed for genetic distance among the C. moschata landraces showed that most likely genetic losses is in progress in that region of cultivation due to anthropic and market pressure, which are stimulating the small farmers to abandon their local varieties in order to use commercial seeds, including hybrids, which is causing risk of genetic erosion

CRISPR-transient expression in soybean for simplified gRNA screening in planta

O objetivo deste trabalho foi desenvolver um método para criar e validar sistemas CRISPR-Cas e diferentes gRNAs em embriões de soja (Glycine max). Dois genes modelo foram usados para mutação simples com um gRNA ou deleção parcial do gene com dois guias. Os gRNAs foram inseridos nos vetores de transformação CRISPR por uma enzima de restrição do tipo IIS ou por subclonagem e inserção do promotor + gRNA2 no vetor de transformação final, com uso do método clássico de clonagem por enzimas de restrição. Os vetores foram construídos com sucesso para um e dois gRNAs. A transformação transiente de soja por Agrobacterium foi realizada para testar a qualidade dos gRNAs e do próprio sistema (cassete de expressão). Detectaram-se mutação simples e deleção gênica nos embriões transformados após o enriquecimento do DNA por digestão seguida de reação em cadeia da polimerase e sequenciamento, o que indica que o sistema CRISPR-Cas e os guias estavam funcionando. Este protocolo pode ser usado para acelerar as estratégias de edição de genoma baseadas em CRISPR, para transformação genética em soja.The objective of this work was to develop a method to create and validate CRISPR-Cas systems and different gRNAs in soybean (Glycine max) embryos. Two model genes were used for simple mutation with one gRNA or partial gene deletion with two guides. The gRNAs were inserted into the CRISPR transformation vectors by a type IIS restriction enzyme or by subcloning and inserting the promoter + gRNA2 in the final transformation vector using the classic restriction enzyme cloning method. The vectors were successfully constructed for one and two gRNAs. Agrobacterium-mediated transient transformation in soybean was carried out to test the quality of gRNAs and of the system itself (expression cassette). Simple mutation and gene deletion were detected in the embryos transformed after DNA enrichment by enzyme digestion followed by polymerase chain reaction and sequencing, which indicates that the CRISPR-Cas system and guides were working. This protocol can be used to accelerate CRISPR-based genome editing strategies for genetic transformation in soybean

Brazilian maize landraces variability under high and low phosphorus inputs

Landraces are considered important sources of abiotic stress tolerance. Among the different abiotic stresses, phosphorous (P) deficiency is considered one of the limiting factors in tropical and subtropical soils. Thus, the aim of the present work is to evaluate and compare P acquisition and use efficiency in landraces and improved varieties of maize in Brazil and classify varieties based on their performance (yield) under low (efficient versus inefficient)and high (responsive versus non-responsive) P supplementation. It also investigates the relationship among variables in regards to P use efficiency(PUE) and agronomic traits and evaluates genetic diversity among varieties. Thirteen landraces varieties and five improved varieties were evaluated in two P-contrasting experiments (with and without P application during sowing) in two counties (Londrina and Maringá), Paraná, Brazil. There was a wide genetic variability among the varieties for the agronomic and P efficiency traits. P acquisition efficiency(PAE) showed high correlation with PUE and grain yield (GY). On the other hand, no correlation was detected between PUE and GY for P use internal efficiency(PUTE). In the experiment without P at sowing, the improved variety ST0509 showed high values for PUE and GY, whereas, among the landraces, the varieties Amarelão, Caiano and Caiano 2 stood out, being considered promising varieties for future PUE breeding programs

Harvest season and seed physiological potential of ‘dedo-de-moça BRS Mari’ hot peppers

The cultivation of chili peppers (Capsicum spp.) plays a key role in the fresh vegetable, condiment, and preserve markets. The determination of the harvest season suitable for seed production is crucial to obtain high-quality seeds and ensure production success. Therefore, this study aimed to determine the harvest season of ‘dedo-de-moça BRS Mari’ hot peppers that provides the maximum seed physiological potential. The flowers in anthesis were labeled daily and the fruits were harvested 25, 40, 55, 70, 85, and 100 days after anthesis (DAA) and classified as green, yellowish green, orange, red, extreme red, and intense red, respectively. The seed physiological potential was determined by using the water content, dry matter, germination, first germination count, germination rate index, and accelerated aging tests. The seed dry matter increased steadily until 55 DAA (3.95 mg per seed), then increased slightly to 70 DAA (4.05 mg per seed), and stabilized from 85 to 100 DAA. The harvested seeds began to germinate at 55 DAA with approximately 40% germination, which peaked at 70 DAA with 87% germination; this value was maintained until 100 DAA. The highest values of the germination rate index were found at 70, 85, and 100 DAA. An increase in seed vigor was observed, based on the accelerated aging test, which peaked at 85 DAA and subsequently decreased. The peppers were harvested between 70 and 85 DAA and red to extreme red were found to be the most recommended colors to obtain ‘dedo-de-moça BRS Mari’ hot pepper seeds with high physiological potential

Quantification of the diversity among common bean accessions using Ward-MLM strategy

O objetivo deste trabalho foi avaliar a divergência de acessos de feijoeiro-comum por suas características agronômicas, morfológicas e moleculares, com base no procedimento Ward-MLM. Uma coleção de 57 acessos do banco de germoplasma da Universidade Federal do Espírito Santo foi utilizada neste estudo, dos quais: 31 acessos locais, pertencentes à comunidade Fortaleza, no Município de Muqui, ES; 20 acessos fornecidos pela Embrapa Trigo; e 6 cultivares comerciais. Foram avaliados cinco caracteres agronômicos (ciclo da planta, número de sementes por vagem, número de vagens por planta, peso de 100 grãos e produtividade de grãos), cinco caracteres morfológicos (hábito de crescimento, porte da planta, formato da semente, cor da semente e grupo comercial) e 16 iniciadores microssatélites. Detectou-se ampla variabilidade genética pelos dados morfológicos, agronômicos e moleculares nos 57 acessos de feijão. O procedimento Ward-MLM mostrou que cinco foi o número ideal de grupos, de acordo com os critérios do pseudo F e pseudo t2 . Os acessos de origem andina tiveram sementes mais pesadas do que os outros e ficaram em um mesmo grupo. O procedimento Ward-MLM é uma técnica útil para detectar divergência genética e agrupar genótipos pelo uso simultâneo de descritores morfológicos, agronômicos e moleculares.The present work aimed at evaluating the divergence among common bean accessions by their agronomic, morphological and molecular traits, based on the Ward-MLM procedure. A collection of 57 accessions from the gene bank of Universidade Federal do Espírito Santo was used in this study, from which: 31 were landraces belonging to the community Fortaleza, in the municipality of Muqui, ES, Brazil; 20 accessions were provided by Embrapa Trigo; and 6 were commercial cultivars. Five agronomic traits (plant cycle, number of seeds per pod, number of pods per plant, weight of 100 seeds, and grain yield), five morphological traits (growth habit, plant size, seed shape, seed color, and commercial group) and 16 microsatellite primers were evaluated. High genetic variability was detected considering morphological, agronomic and molecular traits in the 57 common bean accessions studied. The Ward-MLM procedure showed that the ideal number of groups was five, according to the pseudo F and pseudo t2 criteria. The accessions from Andean origin had heavier seeds than others and formed a cluster. The Ward-MLM statistical procedure is a useful technique to detect genetic divergence and to cluster genotypes by simultaneously using morphological, agronomic and molecular data