Marker-assisted selection in faba bean (Vicia faba L.)

Among the multiple applications of DNA markers in breeding, the most promising for cultivar development is marker-assisted selection (MAS). Genetic improvement by MAS has been carried out with success in several legume crops such as soybean, common bean and pea, however, in other species such as faba bean it is still in its early stages. This article provides an overview of the genomic resources and molecular markers currently available in faba bean, with an emphasis on development and application of MAS for genetic improvement of the crop. In general, genetically simple traits have received more attention than genetically complex characters encoded by multiple genes. Research has mainly focussed on developing molecular markers for selecting resistance to a parasitic weed and other major diseases. As a result, molecular breeding for resistance to crenate broomrape, ascochyta blight, rust and chocolate spot is underway, and promising results have been obtained. Recently, markers linked to a gene controlling growth habit or to select against traits affecting the nutritional value of seeds (tannins, vicine and convicine content) have also been reported, which may facilitate a more efficient selection of new cultivars free of anti-nutritional compounds. In the near future, molecular markers should be developed for many other highly sought-after traits that are difficult to breed conventionally such as frost or drought tolerance. Comparative genomics and synteny analyses with closely related legumes, together with extensive mapping of resistance gene analogs (RGAs), will reveal new candidate genes and selectable markers for use in MAS. Finally genomic tools such as macro- and microarrays may eventually become available for use in faba crop improvement.     

Epidemiology and control of chocolate spot (Botrytis fabae) on winter field beans (Vicia faba)

Dispersal of Botrytis fabae spores and the development of chocolate spot lesions were monitored in crops of winter-sown field beans during the 1980/81, 1981/82 and 1982/83 seasons. The greatest numbers of B. fabae spores collected on horizontal sticky slides exposed in crops were associated with periods of heavy rain and numbers declined if weather was dry. Amounts of chocolate spot developing on leaves of young potted plants exposed in crops near the slides followed the same trends as spore numbers. When numerous spores were collected, abundant chocolate spot developed on the leaves of tagged plants in the crops. Benomyl sprays were applied (at 0·5 kg a.i./ha) either after peaks in numbers of spores collected or according to crop growth stages. Sprays applied in January–April generally gave no increase in yield whether or not timed according to spore peaks. The greatest yields were obtained from plots sprayed in late May, at the midflowering stage of crop growth.     

An effect of rust (Uromyces viciae-fabae) on the yield of spring-sown field beans (Vicia faba) in the UK

Rust (Uromyces viciae-fabae) has recently been noted with increased frequency and earliness on spring-sown beans (Vicia faba) at Rothamsted. In 1982 an experiment was made to assess the damage and yield loss, if any, being caused by the disease. Plots received benomyl sprays to control chocolate spot (Botrytis fabae) or not, maneb plus mancozeb (protective) or propiconazole (systemic) fungicide applied twice or three times to control rust, or no fungicide at all. Rust was first found on 7 July and sprays were applied from 9 July but by 19 August plants of all treatments were dead. Fungicides controlled disease development during July and at harvest overall yields were 4·51 and 5·43 t/ha in unsprayed and sprayed treatments respectively. The difference was accounted for by the weight of individual grains and not by the number of pods per plant or grains per pod. Previously rust has been considered unimportant in the UK but its potential for damage is considerable.     

Nutritional value of faba bean (Vicia faba L.) seeds for feed and food

Faba bean (Vicia faba L.) is a protein-rich legume seed well adapted to most climatic areas of Europe and widely used for feed and food. Even if the seed is generally recognized to be of good nutritional value, existing genetic variability for seed composition offers possibilities for improvement of this trait by breeding. Four major quality types must be distinguished according to the presence or absence of tannins in the integuments and of vicine (V) and convicine (C) in the cotyledons. The nutritional value of diets containing varying amounts of different faba bean cultivars characterized by high or low levels of tannins, and high or low levels of vicine + convicine (VC), has been examined in monogastric animals and ruminants. Low-tannin content generally results in higher protein and energy digestibility for monogastric animals and low VC content has a positive effect on laying hen and broiler production performances. V and C, inactive precursors of divicine and isouramil are redox compounds potentially toxic to human carriers of a widespread genetic deficiency of the erythrocyte (red blood cell, RBC) enzyme glucose-6-phosphate dehydrogenase (G6PD). Ingestion of faba beans by these deficient individuals may cause a severe, potentially lethal hemolytic anemia (favism). The mechanism of action of divicine and isouramil in the G6PD-deficient RBC is discussed.     

Study of faba bean (Vicia faba L.) winter-hardiness and development of screening methods

In cool-temperate regions, faba bean (Vicia faba L.) is mainly grown as a spring crop despite the higher yield potential of the winter type, because of the insufficient winter-hardiness of the present winter genotypes. The objective of this study was to assess winter-hardiness and frost tolerance, to quantify the hardening effect on physiological traits, and to identify auxiliary traits for winter-hardiness. To do so, 31 representative entries were tested in controlled frost tests for frost tolerance and in 12 European environments for winter-hardiness. Total fatty acid composition, proline content, and electrolyte leakage of leaves were analysed. Across all environments, five European winter genotypes were identified with superior winter-hardiness. Controlled frost tests indicated that frost tolerance is a significant, but not an exhaustive component of winter-hardiness (0.021 < |r| < 0.737**). These tests revealed the high frost tolerance of several poorly winter-hardy experimental lines and the limited frost tolerance of well-known winter types. Fatty acid changes due to hardening, proline content, and electrolyte leakage were more strongly correlated with frost tolerance than with field-based winter-hardiness. Although frost tolerance, fatty acid composition, proline content, and electrolyte leakage were significantly correlated with winter-hardiness, the rather low correlation values do not allow a general use of one of them alone to indirectly select for winter-hardiness.     

Diversity maintenance and use of Vicia faba L. genetic resources

The faba bean (Vicia faba L.) is an ancient crop that is represented in collections by cultivated forms only. Botanic and molecular data suggest that the wild ancestor of this species has not yet been discovered or has become extinct. This fact makes ex situ collections more crucial for the present and future breeding activities of this crop, especially when the modernization of agriculture reduces genetic diversity.     

Spatial distribution and temporal stability of crenate broomrape (Orobanche crenata Forsk) in faba bean (Vicia faba L.): A long-term study at two localities

Long-term field studies were conducted at two locations to describe the spatial distribution and temporal stability of Orobanche crenata infestation in faba bean. Spatial analysis with distance indices (SADIE) was used to provide aggregation indices for the distribution of O. crenata at different times. SADIE spatial association index was used to measure the spatial stability of O. crenata aggregation patterns through time.     

Local vs. formal breeding and inbred line vs. synthetic cultivar for organic farming: Case of Vicia faba L.

As organic farming refrains from the use of agrochemical inputs, it is characterized by large environmental heterogeneity. Genotype × location interaction is expected to be larger across organic cropping areas than across conventional ones. When breeding for organic farming, it is important to identify an adequate breeding approach and type of cultivar. The objective was to investigate in the case of faba bean (Vicia faba L.) the effectiveness of local breeding (exploiting local adaptation) vs. formal breeding (exploiting broad adaptation) for grain yield in organic farming and to compare the performance of two types of cultivars: inbred lines and synthetics. A set of 18 inbred lines, their polycross progenies and 13 checks was tested in five locations in Germany from 2004 to 2006. Due to the large genotype × location interaction, local breeding generated higher gains from selection than formal breeding. Based on estimates of genotypic performance and variance of inbred lines and polycross progenies, the best synthetic cultivar at generation Syn-1 and the best inbred line cultivar were predicted. Despite the large variance among inbred lines available in local breeding, the highest performing entry in both breeding strategies was a synthetic, due to its partial realization of heterosis.     

Identification and multi-environment validation of resistance to Botrytis fabae in Vicia faba

The aim of this work was to find new sources of resistance to chocolate spot disease, and to validate their stability across different environments. In order to do so, a collection of 307 accessions of Vicia faba was screened for resistance to Botrytis fabae under field conditions; stability of resistance of the 40 most-resistant accessions was tested in a multi-location experiment in Austria, Chile, Egypt, France and Spain over two field seasons. Although complete resistance was not found, nine accessions showed interesting levels of incomplete resistance (ranging from 10 to 20% of average severity across environments, maximum average severity being 47.9%). Genotype × environment interaction accounted for 22% of the sum of squares of the multi-environment evaluation, revealing instability of the phenotypic expression across environments. This usually hampers the efficiency of selection and reduces the adaptability of the plant material. Three accessions stand out for their consistent resistance, both in terms of reduced disease severity and high stability, which make them good candidates for breeding programs. As for environments, those with the highest total severity mean were the most discriminant between accessions. In contrast, those with lower severity means were the most representative of the whole range of environments. It can be concluded that validation of resistance to chocolate spot in different environments is an essential step when screening for material of interest and should be taken into account for further works.     

Multiple-disease resistance in Vicia faba: Multi-environment field testing for identification of combined resistance to rust and chocolate spot

The aim of this work was to identify Vicia faba germplasm resistant both to rust and chocolate spot. A collection of 43 accessions of V. faba previously identified as chocolate-spot resistant was evaluated for rust and chocolate spot resistance in Egypt and in Spain. The genotype and genotype × environment (GGE) biplot analyses allowed the selection of 11 accessions resistant to both diseases in those locations. These 11 accessions were evaluated for rust in an additional field trial in Spain, all performing better than the susceptible check. The joint analysis of the 11 accessions in the four field trials where they had been evaluated revealed no significant effects either for genotype, environment or the genotype × environment interaction. They are hence promising sources of resistance, both for their low severities and their stable responses across the studied environments. This collection was also tested under controlled conditions against the Egyptian and the Spanish isolates of rust present in the field trials further underlining the stable performance of these genotypes. Finally, the effect of previous infection with chocolate spot on rust resistance was assessed under controlled conditions and no influence of it was found.     

Growth,PAR use efficiency,and yield components of field-grown Vicia faba L. under different temperature and photoperiod regimes

N-fixing legume crops may be a good component of a general plan to improve cropping system efficiency. For this purpose, crop suitability to specific environments must be established. To estimate the yield potential we examined the growth and yield response of faba bean (Vicia faba L.) crops to different thermal and photoperiod regimes. Irrigated field experiments were conducted in northwest Spain for 3 years (2004–2007) with cv. ‘Alameda’ sown on five different dates in each year from mid-autumn to mid-spring. Environmental conditions experienced by plants across sowing dates were largely different. Sowing date had a great influence on biomass, grain yield and its components. This effect was associated with changes in PAR captured, PAR use efficiency (PUE) and biomass allocation to the different organs. Critical leaf area index (LAI_cr) tended to increase and the extinction coefficient, k, to decrease as the sowing date was delayed. Earlier sowing dates intercepted more radiation over the whole season than the spring sowing dates. Greatest crop growth treatments (2nd and 3rd sowing dates) had the highest values of PAR use efficiency probably due to more adequate temperatures for photosynthesis and a large number of reproductive sinks. The highest grain yield (7733 kg ha⁻¹) was obtained with the mid-February sowing date, which produced the most pods and seeds per m², the largest harvest index (62.0%), and large maximum leaf area index (5.41). Low yields of mid-autumn (1st) and mid-spring (5th) sowing dates were associated with reduced pods and seeds per m². Temperature and photoperiod had a large impact on faba bean growth, development, and yield. Best yields were obtained when abundant assimilate supply and moderate temperatures were available during pod set.     

Conversion of starch from dry common beans (Phaseolus vulgaris L.) to ethanol

Dry common beans (Phaseolus vulgaris L.) were evaluated for potential conversion of starch to ethanol. Eight varieties of beans with average starch content of 46% (db) were assayed in a laboratory-scaled process based upon the commercial corn dry grind fermentation process. Ethanol yield was 0.43-0.51 g ethanol/g glucose (0.19-0.23 g ethanol/g beans). The average ethanol yield for the eight bean types was 92% of maximum theoretical yield, demonstrating that starch from beans could be efficiently converted to ethanol. Ethanol concentration obtained from 20% (w/w) solids loading was 3.5-4.4% (w/v). The residual fermentation solids contained, on a dry basis, 37.1-43.6% crude protein, 10.8-15.1% acid detergent fiber and 19.1-31.3% neutral detergent fiber.     

Storage-induced changes in einkorn (Triticum monococcum L.) and breadwheat (Triticum aestivum L. ssp. aestivum) flours

To assess the effect of ageing on alpha-amylase activity, falling number, pasting properties and SDS sedimentation volume, whole meal and white flours of einkorn (cv Monlis) and bread wheat (cv Serio) were stored in darkness at different temperatures and analysed several times up to 374 days. Pregerminated bread wheat flours (cv Blasco) were also evaluated.     

Review of grapes Vitis sp. as an occasional host for Queensland fruit fly Bactrocera. tryoni (Froggatt) (Diptera: Tephritidae)

The recognition of grapes as a host of Queensland fruit fly Bactrocera tryoni (Froggatt) (Qfly) has been inconsistent across Australian states due to the variable nature of reports. Here the current state of knowledge is reviewed. Grapes are not a preferred Qfly host and attacks are infrequent. Infestations were reported to be more common in coastal and subtropical areas or in periods of high rainfall associated with the low availability of preferred hosts. Egg survival appears to be low, although larval survival may be considerably higher. This review has identified a range of literature referring to grapes as a host of Qfly. A review of overseas literature also indicates that grapes are a host for several other fruit fly species.     

Quick-cooking beans (Phaseolus vulgaris L.): I. Investigations on quality

Soaking three beans cultivars (Phaseolus vulgaris L.: Great Northern, kidney, and pinto) in mixed salt solution (sodium chloride 2.5% + sodium bicarbonate 1.5% + sodium tripolyphosphate 1.0% + sodium carbonate 0.5%) resulted in 80%–85% reduction in cooking time over corresponding controls. Irradiation (-rays) at 500 krads of soaked and dehydrated beans caused a reduction of nearly 50% in cooking time. Water uptake and leaching losses for each treatment during soaking at 22°, 37°, and 45°C were investigated. High temperature (37° and 45°C) and pH (9.0) caused greater water imbibition and total solid loss than at room temperature (22°C). Organoleptic evaluation revealed that quick-cooking Great Northern beans appear to be more acceptable than kidney and pinto beans. Quick-cooking cooked beans had better in vitro protein digestibility than conventionally cooked beans. Phenolic content was found to be inversely related to in vitro digestibility.Utah Agricultural Experiment Station Journal article no. 2481.     

Studies on green beans (Phaseolus vulgaris L.)

The phytoalexins produced after the inoculation of green bean pods (Phaseolus vulgaris L.) with the spore suspension of three fungi viz.Fusarium solani, Penicillium patulum andPhytophthora megasperma were studied. Five phytoalexins were isolated and identified as phaseollin, coumestrol, kievitone, phaseollidin and 6--hydroxyphaseollin. Their identity was proved according to m.p., TLC, UV and MS by comparison with authentics. Moreover, the preliminary screening of their antifungal activity was carried out.     

Response of spring planted barley (Hordeum vulgare L.), oats (Avena sativa L.) and wheat (Triticum aestivum L.) to mesotrione

There is little information on the response of spring planted barley (Hordeum vulgare L.), oats (Avena sativa L.) and wheat (Triticum aestivum L.) to mesotrione under Ontario environmental conditions. Four field studies were conducted in Ontario, Canada over a two-year period (2008 and 2009) to evaluate the sensitivity of spring planted cereals (barley, oats, and wheat) to pre-emergence (PRE) and post-emergence (POST) applications of mesotrione at 50, 100, and 150 g ai ha⁻¹. Mesotrione applied PRE caused minimal visible injury at 3, 7, 14 and 28 days after emergence (DAE) and had no adverse effect on plant height or yield of barley, oats and wheat. Mesotrione applied POST caused as much 11% injury and reduced plant height as much as 6% in spring planted cereals. Injury was higher in wheat compared to barley or oats. Mesotrione applied POST had no adverse effect on the yield of barley or oats but decreased the yield of wheat as much as 14%. Based on this study, mesotrione applied PRE at 50, 100 or 150 g ai ha⁻¹ can be safely used in spring planted barley, oats, and wheat. Mesotrione applied POST at the proposed dose of 50, 100 or 150 g ai ha⁻¹ can also be safely used in spring planted barley and oats. However, mesotrione applied POST results in unacceptable injury in spring planted wheat.     

Conversion into bioethanol of insect (Sitophilus zeamais Motschulsky), mold (Aspergillus flavus Link) and sprout-damaged maize (Zea mays L.) and sorghum (Sorghum bicolor L. Moench)

The bioconversion into ethanol of insect (Sitophilus zeamais), mold (Aspergillus flavus) and sprout-damaged maize and sorghum was investigated. Kernel test weight losses due to insect damage in maize were almost twice compared to sorghum (18.6 vs. 10.7%). All damaged kernels lost some of the starch and increased soluble sugars, ash and crude fiber. The mold-damaged sorghum contained approximately five times more FAN compared to the control. The sprout-damaged kernels contained the highest amounts of reducing sugars prior (11 g/L) to and at the end (146.5 g/L) of liquefaction with α-amylase. Ethanol yields based on the already damaged grain indicated that sprout-damaged kernels yielded similar amounts compared to sound kernels (381.1 vs. 382.6 L/ton and 376.6 vs. 374.8 L/ton of sorghum or maize respectively). The insect-damaged maize and sorghum have reduced ethanol yields compared with the controls (29 and 23% respectively), and this negative result was mainly due to dry matter losses during the inadequate storage. Despite differences in ethanol yield, all treatments have similar conversion efficiencies (76.1–89.9%) indicating the robustness of yeast facing biotic-damaged feedstocks. This research demonstrates that the use of already damaged insect, mold or sprouted kernels is feasible and a good alternative for biorefineries.     

Abundance of Sitona lineatus L. (Col., Curculionidae) in peas (Pisum sativum L.): Effects on yield parameters and nitrogen balance

In a four-year study, we investigated the relationship between the damage to root nodules of organically produced pea (Pisum sativum L.) by the larvae of the pea leaf weevil (Sitona lineatus L.) and the abundance of adult weevils. In addition to studying natural infestations, we established artificial infestations within cages to assess the impact of different weevil densities on yield parameters and determinants of the nitrogen balance. Densities of 0.2 adult S. lineatus per plant (20 individuals per m²) reduced the number of seeds and pods per plant by 18% and 15%, respectively; seeds per pod and thousand-seed weight remained unaffected. A three-fold or five-fold increase in weevil abundance (13–40 or 20 to 100 individuals per m²) did not result in an additional reduction in yield. Moreover, the higher weevil abundance did not adversely affect the N-harvest index or soil nitrogen content. We suspect that the impact of adult S. lineatus on yield and nitrogen parameters is limited by the density-dependent mortality of the larvae. Survival of larvae in turn depends on the nodulation of the plants, which is largely regulated by the supply of water. The assumption that organic cropping systems are at specific risk from the pea leaf weevil was confirmed by increasing population densities during the study period. However, yield losses were independent of adult attack within a wide range of weevil abundance, which indicates the complexity of assessing larval damage based on adult infestation level. An enhanced intraspecific competition among larvae may account for the absence of linear relationships, considering that especially young instars failed to establish in root nodules at higher densities. We found that adult densities of 0.2 individuals per plant and subsequent larval densities of 7 individuals per plant resulted in destruction of 37% of the root nodules on primary roots, which was much below destruction values reported in other studies. In conclusion, we recommend an early monitoring of weevils and early initiation of control strategies because yield losses were caused by even low weevil densities. Finally, the tolerance of P. sativum to S. lineatus was influenced by the yield level, i.e., tolerance to S. lineatus decreased as yield increased.     

Arthropod communities related to different mixtures of oil (Glycine max L. Merr.) and essential oil (Artemisia annua L.) crops

Plants can host many herbivores and their natural enemies during their growth cycles. For this reason, changes in the relative abundance of crop and weed plants in a monocropping system as well as different crop plants in an intercropping system may produce great bottom up impacts in the specific and functional structure of spontaneous communities of arthropods. The hypothesis of this study was that the combination of two contrasting species, soybean (Glycine max, Fabaceae, N₂ fixing plant) and annual wormwood (Artemisia annua, Asteraceae, VOCs plant), would be related to different spontaneous communities of arthropods depending on the proportion of each species, and this would favor crop biodiversity without compromising crop production. The objectives of the study were: (a) to analyze the differences of spontaneous communities of arthropods related to different soybean (S)-annual wormwood (W) mixtures, using standard crop management for S production in Argentina, (b) to determine S and W total biomass and W essential oil content and yield and, (c) to analyze the relationship between arthropod communities and crop productivity. Factorial field experiments with 3 replications were done during 2006 and 2007. S density was kept constant (40 plants m⁻²) and different W densities (plants m⁻²) were added. Treatments were pure S, S + 2W, S + 4W, S + 8W and pure W (8 plants m⁻²). Arthropods were sampled at soybean full flowering and were classified in functional groups as herbivores and non-herbivores. S and W total and relative biomass and W essential oil content and yield from leaves and inflorescences were estimated in reproductive stage. Arthropod morphospecies abundance and richness were determined for each treatment. Data were analyzed using uni (ANOVA) and multivariate (CCA) techniques. Arthropods belonging to 7 orders presented a total richness of 48 morphospecies in 2006 and 36 in 2007, while total abundance was 379 in 2006 and 318 in 2007. The proportion of non-herbivores was higher than the proportion of herbivores. Different arthropod communities were observed according to each treatment. No differences were found among treatments in S + W and S total biomass production, while W total biomass and essential oil yield were both different among treatments. Relative biomass production of S and W was the main explanatory variable related to the contrast of arthropod communities between pure annual wormwood (W) and the rest of the treatments. Annual wormwood could be used as an accompanying essential oil crop or left as a weed in the densities tested in this work, favoring biodiversity and, eventually, pest management without compromising soybean crop yield.