Genetic Variability of Mineral Content in Different Grain Structures of Bean Cultivars from Mesoamerican and Andean Gene Pools.

Beans (Phaseolus vulgaris L.) are an important source of proteins, carbohydrates, and micronutrients in the diets of millions of people in Latin America and Africa. Studies related to genetic variability in the accumulation and distribution of nutrients are valuable for biofortification programs, as there is evidence that the seed coat and embryo differ in the bioavailability of essential nutrients. In this study, we sought to evaluate the genetic variability of total mineral content in the grain and its constituent parts (seed coat, cotyledon, and embryonic axis) of bean genotypes from Mesoamerican and Andean centers of origin. Grain samples of 10 bean cultivars were analyzed for the content of proteins and minerals (Mg, Ca, K, P, Mn, S, Cu, B, Fe, and Zn) in the whole grains and seed coat, cotyledons, and embryonic axis tissues. Genetic variability was observed among the cultivars for protein content and all evaluated minerals. Moreover, differential accumulation of minerals was observed in the seed coat, cotyledons, and embryonic axis. Except for Ca, which accumulated predominantly in the seed coat, higher percentages of minerals were detected in the cotyledons. Furthermore, 100-grain mass values showed negative correlations with the contents of Ca, Mg, P, Zn, Fe, and Mn in whole grains or in the different grain tissues. In general, the Mesoamerican cultivars showed a higher concentration of minerals in the grains, whereas Andean cultivars showed higher concentrations of protein.

Diversity of nutritional content in seeds of Brazilian common bean germplasm.

Mineral deficiency is worldwide one of the major problems associated with human health, and biofortification through breeding is considered an important strategy to improve the nutritional content of staple food in countries that face this problem. The assessment of genetic variability for seed nutrient contents is a first step in the development of a biofortified crop. From the germplasm bank IDR-IAPAR-EMATER, a set of 1,512 common bean accessions, consisting of local and commercial varieties and improved lines, was analyzed. High variability among the accessions was observed for all evaluated nutrient contents (P, K, Ca, Mg, Cu, Zn, Mn, Fe and S and protein). In the mean, the contents of the carioca and black market groups (Mesoamerican gene pool), were around 7% higher for the minerals Ca, Cu, Mn and Fe and between 2-4% higher for P, K, Mg and Zn than in the other groups with Mesoamerican and Andean common bean. Few differences were observed among the Mesoamerican accessions that belong to the carioca and black commercial groups. Wide variability was observed among the evaluated genotypes, and the concentrations of the best accessions exceeded the overall mean by 14-28%. Due to the high variability in the evaluated accessions, these results may contribute to the selection of promising parents for the establishment of mating blocks. The nutritional contents of many of the improved lines evaluated in this study were higher than those of the commercial cultivars, indicating the possibility of developing new biofortified cultivars.

Distinctness of Brazilian common bean cultivars with carioca and black grain by means of morphoagronomic and molecular descriptors.

Common bean (Phaseolus vulgaris L.) is one of the most important legumes for human consumption and is a staple food in the diet of the population of some countries of Latin America, Africa and Asia. The distinction between cultivars is based predominantly on morphological descriptors, which proved inefficient for the differentiation of some cultivars. This study had the objective of describing, distinguishing and evaluating the agronomic potential of 39 common bean cultivars of the carioca and black grain groups registered for cultivation in Brazil, based on 49 morphoagronomic descriptors and microsatellite (simple sequence repeat -SSR) markers. The morphoagronomic traits of each commercial group were characterized in four environments. Thirty-seven SSR markers were used for the molecular description. The morphological data, analyzed by the Shanonon-Weaver index, detected low variability among cultivars for qualitative data. On the other hand, the estimates of variance analysis, relative importance of the traits and hierarchical grouping analysis applied to the quantitative variables showed that the descriptors related to plant morphology were the most important for the carioca group, and those related to seed morphology were determining for the black group. The genetic parameters estimated for SSR markers by hierarchical and Bayesian cluster analysis identified 116 alleles, with 33 and 30 polymorphic loci and 24 and 22 private alleles for the carioca and black groups, respectively. The combined use of morphoagronomic and molecular descriptors improves the distinguishability of cultivars, contributing in a more efficient way to breeding and to the protection of cultivars.

Adaptabilidade e estabilidade produtiva em genótipos precoces defeijão no estado do Paraná / Agronomic performance and grain yield in early common bean genotypes in Paraná state

No desenvolvimento de cultivares de feijão precoce é imprescindível que este apresente elevadorendimento de grãos e comportamento previsível. O objetivo deste trabalho foi avaliar a adaptabilidadee a estabilidade fenotípica para rendimento de grãos em genótipos de feijão precoce. Na safra das águas2004/2005, foram conduzidos experimentos em: Londrina, Irati, Pato Branco e Capitão Leônidas Marques.Na safra da seca/2005, os experimentos foram conduzidos em Pato Branco e Ponta Grossa. O delineamentoexperimental utilizado foi o de blocos casualizados com três repetições e parcelas de duas fileiras de 5 mespaçadas 0,5 m e com uma população de 15 plantas por metro linear. No estádio de maturação fisiológica(R9), foi avaliado o rendimento total dos grãos por parcela sendo esses dados transformados para kg.ha-1 ecorrigidos para 13% de umidade. As análises de variância individuais e análise conjunta dos locaisrevelaram diferenças significativas entre os genótipos estudados. A interação genótipos por ambientefoi significativa a 1% de probabilidade, demonstrando que os genótipos avaliados apresentaram respostasdiferenciadas nos diversos ambientes em que foram avaliados. As linhagens LPSIA 04 103, LPSIA 04 105e LPSIA 04 107 foram consideradas promissoras por apresentarem ampla adaptabilidade (b1i=1), altaestabilidade (s2di=0) e boa produtividade de grãos.

In the development of early beans cultivars it is very important high grain yield and predictable behavior. The objective of this work was to assess adaptability and phenotypic stability grain yield in early common bean genotypes. The experiments were conducted in two cropping season in the following counties: Londrina, Irati, Pato Branco and Capitão Leonidas Marques (wet season 2004/2005); Pato Branco and Ponta Grossa (dry season 2005). Complete randomized block with three replications was used. In the maturation stage (R9) grain yield were assessed and the data were transformed to kg.ha-1 and corrected for 13% humidity. The individual and combined variance analyses indicated significant differences among genotypes. The genotype x environmental interaction was significant considering 1% probability, revealing that the genotypes evaluated performed differently according to the environment where the tests were done. The lines LPSIA 04 103, LPSIA 04 105 and LPSIA 04 107 showed general adaptability (b1i=1), high phenotypic stability (s2 di=0), and superior average yield.