A. M. De Ron

Allozyme evidence supporting southwestern Europe as a secondary center of genetic diversity for the common bean.

Abstract.Genetic diversity within a common bean (Phaseolus vulgaris L.) collection, comprising 343 accessions from the Iberian Peninsula, was examined using six allozyme markers. Two major clusters corresponding to the Andean and Mesoamerican gene pools were identified. Both gene pools were characterized by specific alleles, with the former exhibiting Skdh100, Me100, Rbcs100 or 98 and Diap-1100, and the latter exhibiting Skdh103, Me100, Rbcs100 and Diap-195. Some accessions from both clusters, deviating from these allozyme patterns, exhibited Skdh100, Me100, Rbcs100 and Diap-195 or Skdh103, Me100, Rbcs100 and Diap-1100 allozyme profiles and were considered as putative hybrids.The levels of genetic variation has not been eroded since the introduction of the common bean from the American centers of domestication to the Iberian Peninsula. Instead, obvious signs of introgression between the two gene pools were observed, mainly among white-seeded genotypes. The intermediate forms adapted to the Iberian Peninsula could have emerged from initial recombination between Mesoamerican and Andean gene pools. The Iberian common bean germplasm is therefore more complex than previously thought, and contains additional diversity that remains to be explored for genetic and breeding purposes. The Iberian Peninsula could be considered as a secondary center of genetic diversity of the common bean, especially the large white-seeded genotypes.

A core collection of common bean from the Iberian peninsula

Characterization of crop germplasm from specific regions helps understand the patterns of genetic variation that facilitates further germplasm collection, characterization, management and their more efficient utilization in genetics, breeding and other studies. Common bean (Phaseolus vulgaris L.) is a traditional crop in the Iberian Peninsula (Spain and Portugal) where subsistence farmers have been growing and maintaining their own cultivars since their introductions from the Americas in the sixteenth century. Our objectives were to: (i) characterize diversity in the landraces collected from the Iberian Peninsula and (ii) form a core collection. Of 388 landraces from the major production regions characterized for 34quantitative and 13 qualitative characters, including morphological, agronomic and biochemical traits, 74.7% had an Andean origin, 16.8% a Mesoamerican origin and 8.4% had seed mixtures or were recombinants between the two gene pools. Landraces of indeterminate climbing growth habit Type IV(47.2%) and bush determinate Type I(26.4%) with large (52.9%) and medium(27.4%) seeds of white (38.8%) and cream(25.9%) colour were predominant. Similarly, the ‘T’ phaseolin pattern and common bean race Nueva Granada were the most frequent(51%). Some exceptionally large-seeded landraces of Andean (e.g., PHA-0917 with119 g 100-seed weight-1) and Mesoamerican (e.g., PHA-0399 with 66 g100-seed weight-1) were found. These and other possible recombinants between the two gene pools merit further investigation. Fifty two landraces (13%) were chosen to form a core collection representing the genetic diversity in the Iberian Peninsula.

Interactions of bush bean intercropped with field and sweet maize

Abstract Common bean, Phaseolus vulgaris L., is traditionally intercropped with maize by small-scale farmers in northwest Spain. Interactions of genotypes of beans with cropping systems and seasons were studied to determine if selection of bean in sole cropping would be a valid approach to genetic improvement for intercropping. In this experiment, 10 dry bush bean varieties were evaluated in sole cropping and intercropping with two types of maize (field and sweet maize) at two locations for 2 years. The performance of bean genotypes in each cropping system was compared with respect to developmental plant characteristics, seed yield and yield components and food quality traits. A significant bean genotype×cropping system interaction was found for period of flowering and seed yield, and there were significant differences between cropping systems for pods per plant, seed length and seed coat proportion. Intercropping with field maize reduced bean yield by 55% and intercropping with sweet maize reduced bean yield by 44%. Significant and high correlations of bean yields were obtained between sole cropping and intercropping with maize. Mean yields were used to calculate the land equivalent ratios (LERs), which averaged 1.12 for intercropping with field maize and 0.93 for intercropping with sweet maize. Specific variety combinations reached LER values greater than one. Net income was higher for some intercrop patterns than for bush bean sole crop. The most competitive bean varieties yielded the most when intercropped with maize but those varieties were not necessarily the highest yielding in sole cropping. The most competitive bean varieties were the latest to flower. The evaluation of bush bean genotypes for agronomic and food quality traits under sole cropping provides sufficient information to select varieties efficiently for the field maize-bean and sweet maize-bean intercropping systems. Greatest net income was realized when bush beans intercropped with sweet maize, provided a system with higher added value compared to intercropping with field maize.

Numerical taxonomy of Iberian pea landraces based on quantitative and qualitative characters

SummaryA multivariate statistical method was applied on 19 quantitative and 11 qualitative traits in order to classify 105 pea landraces from the Northwest of the Iberian Peninsula. Ten elite cultivars were used as controls. The eleven qualitative characters were transformed by special coding. A procedure of data analyzed based on the combined resemblance matrix as a result of the joint resemblance matrix for quantitative and qualitative traits was constructed and described. The 105 pea landraces display a wide diversity at the infraspecific level for the 19 quantitative traits, however, just ten of them plus one qualitative trait could be considered as good descriptors for the pea landraces studied. The grouping patterns of the landraces did not reflect geographical origin, but provided taxonomically useful results, since it shows the possible use of six groups, vis. Group I (12 landraces), includes accessions which could be used for green and canned consumption, Group IV (18 landraces) includes edible-podded types and Group V (12 landraces) could be used for field pea (dry seed cultivars), Groups VI and VIII (each with 26 accessions) are also extremely interesting because of their heterogeneity.

Genetic diversity in pod and seed quality traits of common bean populations from northwestern Spain

Common bean (Phaseolus vulgaris L.) is an important food in the northwest of Spain where it is consumed as either green pods or dry seeds after cooking. Quality properties play a major role in cultivar acceptance by processors and consumers. To determine if sufficient variation in important culinary and nutritional traits exists within common bean, fifty-nine populations (plus five commercial cultivars) were grown in the northwest of the Iberian Peninsula in three different environments and evaluated for sixteen fresh pod and dry seed quality traits. Populations showed significant differences for pod curvature, length/width and width/thickness ratios of pod and seed, pod and seed texture, volume, hardness, seed coat percentage and water absorption of seed, crude protein, crude fat, crude fiber, toal sugars and starch content. Genotype × environment interaction was significant for fresh pod traits such as curvature, length/width and width/thickness ratios, and texture, and for dry seed traits such as length/width and width/thickness ratios, volume, hardness and water absorption. Estimates of heritabilities and constancies (genotypic/environmental variance) were higher than 0.5 and 1.0 respectively for pod curvature, length/width and width/thickness ratios of pod and seed, seed volume and seed water absorption. There were high correlations of pod texture with seed length/width and width-thickness ratios, seed coat percentage, seed water absorption, crude fat, total sugars, starch content and crude fiber. Pod texture could be used as an important parameter for evaluating both seed culinary and nutritional quality. In addition, 17 populations showed promise as parental material in a breeding program for pod and seed culinary quality and protein content. The culinary and nutritional quality potential of the accessions such as PHA-0171, PHA-0253 and PHA-0257 which are known as Alubias de riñón could be the base material in a breeding program to obtain accessions with a good seed quality.

2-DE-based proteomic analysis of common bean (Phaseolus vulgaris L.) seeds

Common bean (Phaseolus vulgaris L.) is the most important grain legume for direct human consumption. Proteomic studies in legumes have increased significantly in the last years but few studies have been performed to date in P. vulgaris. We report here a proteomic analysis of bean seeds by two-dimensional electrophoresis (2-DE). Three different protein extraction methods (TCA-acetone, phenol and the commercial clean-up kit) were used taking into account that the extractome can have a determinant impact on the level of quality of downstream protein separation and identification. To demonstrate the quality of the 2-DE analysis, a selection of 50 gel spots was used in protein identification by mass spectrometry (MALDI-TOF MS and MALDI-TOF/TOF). The results showed that a considerable proportion of spots (70%) were identified in spite of incomplete genome/protein databases for bean and other legume species. Most identified proteins corresponded to storage protein, carbohydrate metabolism, defense and stress response, including proteins highly abundant in the seed of P. vulgaris such as the phaseolin, the phytohemagglutinin and the lectin-related α-amylase inhibitor.

Food and feed potential breeding value of green, dry and vegetable pea germplasm

Pea is an important grain legume and vegetable in the South of Europe where it is grown on small farms and gardens using traditional varieties and methods during the winter. Variability in old, unimproved varieties needs to be determined in order to create useful genetic variation for broadening the narrow genetic base of commercial cultivars and for making efficient use of available resources. One hundred and four unimproved pea varieties and ten elite cultivars were evaluated in 1991 and 1992 at two locations for seed and vegetable quality, canopy and agronomic traits. Significant genotype by environment (G × E) interactions were found for protein concentration, fresh seed size and weight, canopy traits, pod length and weight, days to flowering, and days to fresh seed and pod maturity. There were significant differences between unimproved pea varieties for all traits studied except for seed soluble sugars and seed tenderness. Most of the significant differences for seed and vegetable quality traits were...

Breeding Annual Grain Legumes for Sustainable Agriculture: New Methods to Approach Complex Traits and Target New Cultivar Ideotypes

Although yield and total biomass produced by annual legumes remain major objectives for breeders, other issues such as environment-friendly, resource use efficiency including symbiotic performance, resilient production in the context of climate change, adaptation to sustainable cropping systems (reducing leaching, greenhouse gas emissions and pesticide residues), adaptation to diverse uses (seeds for feed, food, non-food, forage or green manure) and finally new ecological services such as pollinator protection, imply the need for definition of new ideotypes and development of innovative genotypes to enhance their commercialization. Taken as a whole, this means more complex and integrated objectives for breeders. Several illustrations will be given of breeding such complex traits for different annual legume species. Genetic diversity for root development and for the ability to establish efficient symbioses with rhizobia and mycorrhiza can contribute to better resource management (N, P, water). Shoot architectures and phenologies can contribute to yield and biotic constraint protection (parasitic weeds, diseases or insects) reducing pesticide use. Variable maturity periods and tolerance to biotic and abiotic stresses are key features for the introduction of annual legumes to low input cropping systems and for enlarging cultivated area. Adaptation to intercropping requires adapted genotypes. Improved health and nutritional value for humans are key objectives for developing new markets. Modifying product composition often requires the development of specific cultivars and sometimes the need to break negative genetic correlations with yield. A holistic approach in legume breeding is important for defining objectives with farmers, processors and consumers. The cultivar structures are likely to be more complex, combining genotypes, plant species and associated symbionts. New tools to build and evaluate them are important if legumes are to deliver their exciting potential in terms of agricultural productivity and sustainability as well as for feed and food.

Effect of intercropping bush bean populations with maize on agronomic traits and their implications for selection

Abstract The effect of intercropping bush bean with maize on several agronomic traits was studied for 25 populations of bush bean. These populations were grown in two field trials in the northwest of Spain in two consecutive years. Population means differed little between cropping systems. Significant differences among populations were found for all characters except end of flowering, period of flowering and pod yield. There were neither cropping system nor populations × cropping system effects for the characters studied. There were significant environment × population interactions in some cases, and this could cause difficulties for future breeding programs. The results suggest that under these environmental conditions, selection under either cropping system would be effective for both.

Diversity of common bean (Phaseolus vulgaris L.) germplasm from Portugal

Common bean (Phaseolus vulgarisL.) is a traditional crop in Portugal, where farmers growvarieties selected and maintained by themselves. A collection of 88landraces of common bean was evaluated for 17 quantitative andqualitative traits and the biochemical marker phaseolin to displaythe degree of variation of this germplasm. Agronomic data weresubjected to cluster analysis and several groups were identified,with three groups clustering most of the landraces. Regardingphaseolin variation the C and T banding patterns are the mostfrequent ones, so the origin of the Portuguese beans is thus probablythe Andean region of South America. These results give informationabout the origin, diversity and breeding value of the Portuguesegermplasm, that could be useful to widen the genetic base ofcurrently cultivated bean varieties in Europe.