Characterization of genetic variability among common bean genotypes by morphological descriptors

The purpose of this study was to characterize the genetic variability in 100 genotypes of the Active Germplasm Bank of common bean of the Federal University of Viçosa, by morphological descriptors, classify them in groups of genetic similarity and to identify the degree of relevance of descriptors of genetic divergence. The genotypes were evaluated based on 22 quantitative and qualitative morphological descriptors. The high-yielding genotypes V 7936, Gold Gate, LM 95103904, 1829 S 349 Venezuela, and PF 9029975, CNFC 9454 and Fe 732015, with upright growth, have potential for use as parents in common bean breeding programs. By genetic divergence analysis, the genotypes were clustered in eight groups of genetic dissimilarity. By methods of principal components, 9 of the 22 descriptors were eliminated, for being redundant or little variable, suggesting that 10-20 morphological descriptors can be used in studies of characterization of genetic variation

Introgression and pyramiding into common bean market class fabada of genes conferring resistance to anthracnose and potyvirus

Anthracnose and bean common mosaic (BCM) are considered major diseases in common bean crop causing severe yield losses worldwide. This work describes the introgression and pyramiding of genes conferring genetic resistance to BCM and anthracnose local races into line A25, a bean genotype classified as market class fabada. Resistant plants were selected using resistance tests or combining resistance tests and marker-assisted selection. Lines A252, A321, A493, Sanilac BC6-Are, and BRB130 were used as resistance sources. Resistance genes to anthracnose (Co-2 ( C ), Co-2 ( A252 ) and Co-3/9) and/or BCM (I and bc-3) were introgressed in line A25 through six parallel backcrossing programs, and six breeding lines showing a fabada seed phenotype were obtained after six backcross generations: line A1258 from A252; A1231 from A321; A1220 from A493; A1183 and A1878 from Sanilac BC6-Are; and line A2418 from BRB130. Pyramiding of different genes were developed using the pedigree method from a single cross between lines obtained in the introgression step: line A1699 (derived from cross A1258 × A1220), A2438 (A1220 × A1183), A2806 (A1878 × A2418), and A3308 (A1699 × A2806). A characterization based on eight morpho-agronomic traits revealed a limited differentiation among the obtained breeding lines and the recurrent line A25. However, using a set of seven molecular markers linked to the loci used in the breeding programs it was possible to differentiate the 11 fabada lines. Considering the genetic control of the resistance in resistant donor lines, the observed segregations in the last backcrossing generation, the reaction against the pathogens, and the expression of the molecular markers it was also possible to infer the genotype conferring resistance in the ten fabada breeding lines obtained. As a result of these breeding programs, genetic resistance to three anthracnose races controlled by genes included in clusters Co-2 and Co-3/9, and genetic resistance to BCM controlled by genotype I + bc-3 was combined in the fabada line A3308

Genetic diversity analysis of common beans based on molecular markers

A core collection of the common bean (Phaseolus vulgaris L.), representing genetic diversity in the entire Mexican holding, is kept at the INIFAP (Instituto Nacional de Investigaciones Forestales, Agricolas y Pecuarias, Mexico) Germplasm Bank. After evaluation, the genetic structure of this collection (200 accessions) was compared with that of landraces from the states of Oaxaca, Chiapas and Veracruz (10 genotypes from each), as well as a further 10 cultivars, by means of four amplified fragment length polymorphisms (AFLP) +3/+3 primer combinations and seven simple sequence repeats (SSR) loci, in order to define genetic diversity, variability and mutual relationships. Data underwent cluster (UPGMA) and molecular variance (AMOVA) analyses. AFLP analysis produced 530 bands (88.5% polymorphic) while SSR primers amplified 174 alleles, all polymorphic (8.2 alleles per locus). AFLP indicated that the highest genetic diversity was to be found in ten commercial-seed classes from two major groups of accessions from Central Mexico and Chiapas, which seems to be an important center of diversity in the south. A third group included genotypes from Nueva Granada, Mesoamerica, Jalisco and Durango races. Here, SSR analysis indicated a reduced number of shared haplotypes among accessions, whereas the highest genetic components of AMOVA variation were found within accessions. Genetic diversity observed in the common-bean core collection represents an important sample of the total Phaseolus genetic variability at the main Germplasm Bank of INIFAP. Molecular marker strategies could contribute to a better understanding of the genetic structure of the core collection as well as to its improvement and validation

Contribution of the universities to the development of field crop cultivars

Public and private research institutions employ their best efforts to produce new cultivars, which are intended to ensure productivity, reduce ecological footprint and present characteristics that meet consumer expectations. Some Brazilian universities, which are usually originated from schools of higher education in agriculture, have contributed to the breeding of some crops. These universities also aimed to solve the problems of the Brazilian agricultural sector, and became essential tool to make Brazil an important player in the agribusiness world. In the last decades, regarding the five species presented here, the universities have developed 35 oat cultivars and made the country self-sufficient in this grain; they have also developed cultivars of common beans (27), sugarcane (59), soybean (62), and wheat (03), besides countless corn hybrids, since works in this species date before the establishment of the national cultivar registration system.Inúmeras instituições, públicas e privadas, empregam seus melhores esforços para produzir novas cultivares, as quais têm por objetivo garantir a produtividade, reduzir insumos e apresentar características que atendam às expectativas dos consumidores. Algumas universidades brasileiras, em geral originadas de escolas de ensino superior de agricultura, têm contribuído para o melhoramento genético de algumas culturas. Essas universidades também visavam resolver os problemas do setor agropecuário brasileiro, e se tornaram instrumento fundamental para alçar o Brasil como um respeitável ator do agronegócio mundial. Nas últimas décadas, considerando as cinco espécies aqui apresentadas, as Universidades desenvolveram 35 cultivares de aveia branca e tornaram o país autossuficiente nesse grão; desenvolveram 27 cultivares de feijoeiro, 59 de cana-de-açúcar, 62 de soja, 03 de trigo, além de inúmeras e incontáveis cultivares de milho, pois os trabalhos nesta espécie datam muito antes dos registros nacionais de cultivares

The distribution of benefits from public international germplasm banks: the case of beans in Latin America

The unrestricted international flow of genetic resources from international genebank collections is the source of perhaps one of the greatest impacts of international agricultural research. This paper examines the distribution across countries in Latin America of benefits generated from bean genetic resources held by the International Center for Tropical Agriculture (CIAT). The genealogies of commercial bean cultivars released since 1976, containing materials from the collection, are analysed to calculate for each country the source of the genetic resources used. All countries in the region are shown to be heavily dependent on imported genetic resources for their commercial cultivars. From the available information on the economic impact of these improved bean varieties, the share of economic productivity benefits associated with imported germplasm by country of origin is calculated. The benefits received by each country from improved bean germplasm are compared with the contribution of that country's germplasm to other countries. Some of the patterns in the flow and use of genetic resources are analysed. © 2003 Elsevier B.V. All rights reserved