Plant Cyanogenesis of <Emphasis Type="Italic">Phaseolus lunatus</Emphasis> and its Relevance for Herbivore–Plant Interaction: The Importance of Quantitative Data

Quantitative experimental results on the antiherbivorous effect of cyanogenesis are rare. In our analyses, we distinguished between the total amount of cyanide-containing compounds stored in a given tissue [cyanogenic potential (HCNp)] and the capacity for release of HCN per unit time (HCNc) from these cyanogenic precursors as a reaction to herbivory. We analyzed the impact of these cyanogenic features on herbivorous insects using different accessions of lima beans (Phaseolus lunatus L.) with different cyanogenic characteristics in their leaves and fourth instars of the generalist herbivore Schistocerca gregaria Forskål (Orthoptera, Acrididae). Young leaves exhibit a higher HCNp and HCNc than mature leaves. This ontogenetic variability of cyanogenesis was valid for all accessions studied. In no-choice bioassays, feeding of S. gregaria was reduced on high cyanogenic lima beans compared with low cyanogenic beans. A HCNp of about 15 μmol cyanide/g leaf (fresh weight) with a corresponding HCNc of about 1 μmol HCN released from leaf material within the first 10 min after complete tissue disintegration appears to be a threshold at which the first repellent effects on S. gregaria were observed. The repellent effect of cyanogenesis increased above these thresholds of HCNp and HCNc. No repellent action of cyanogenesis was observed on plants with lower HCNp and HCNc. These low cyanogenic accessions of P. lunatus were consumed extensively—with dramatic consequences for the herbivore. After consumption, locusts showed severe symptoms of intoxication. Choice assays confirmed the feeding preference of locusts for low over high cyanogenic leaf material of P. lunatus. The bioassays revealed total losses of HCN between 90 and 99% related to the estimated amount of ingested cyanide-containing compounds by the locusts. This general finding was independent of the cyanogenic status (high or low) of the leaf material.     

Rheological properties and gel strength of Phaseolus lunatus protein/carboxymethylated flamboyant gum systems

The rheological behaviour and gel strength of hydrocolloid mixture systems (HMSs) of carboxymethylated flamboyant gum (CFG) with protein hydrolysates (PHs) of Phaseolus lunatus were examined to evaluate the influence of the protein/polysaccharide ratio (2:1 and 3:1), pH (3 and 9) and concentration of solids, according to a 2³ factorial design. The protein concentrate of P. lunatus was hydrolysed with pepsin–pancreatin enzymes. The flow curve results were fitted to the Ostwald–de Waele model. The flow behaviour index (0.66–0.78) for all conditions studied was indicative of the shear‐thinning behaviour. For the HMS, the consistency index (k) values ranged from 0.4 Pa sⁿ to 1.2 Pa sⁿ. The analyses of variance showed that the ratio of PH/CFG and pH were the main variables that had significant effect on k values (P < 0.05). Only PH system presented a weak gel‐like viscoelastic behaviour. Both functional properties were affected by the protein degree of hydrolysis (DH).     

Isolation and Characterization of 13 New Polymorphic Microsatellite Markers in the Phaseolus vulgaris L. (Common Bean) Genome

In this study, 13 polymorphic microsatellite markers were isolated from the Phaseolus vulgaris L. (common bean) by using the Fast Isolation by AFLP of Sequence COntaining Repeats (FIASCO) protocol. These markers revealed two to seven alleles, with an average of 3.64 alleles per locus. The polymorphic information content (PIC) values ranged from 0.055 to 0.721 over 13 loci, with a mean value of 0.492, and 7 loci having PIC greater than 0.5. The expected heterozygosity (H_E) and observed heterozygosity (H_O) levels ranged from 0.057 to 0.814 and from 0.026 to 0.531, respectively. Cross-species amplification of the 13 prime pairs was performed in its related specie of Vigna unguiculata L. Seven out of all these markers showed cross-species transferability. These markers will be useful for future genetic diversity and population genetics studies for this agricultural specie and its related species.     

豆类双歧杆菌发酵饮料的研制

以糊化赤豆和去腥大豆浆为原料，添加１％的葡萄糖和２％的乳糖等成分，用双歧杆菌、保加利亚乳杆菌和嗜热乳酸链球菌作混合发酵剂，接种量为３％，发酵后可制得含有活菌的豆类发酵饮料。赤豆和大豆的产地对产品质量无影响     

Chemical analysis of French beans (Phaseolus vulgaris L.) by headspace solid phase microextraction (HS-SPME) and simultaneous distillation/extraction (SDE)

Headspace Solid Phase Microextraction (HS-SPME) involving divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fibre and simultaneous distillation/extraction (SDE) techniques were applied to study the volatile and semi volatile compounds of thawed and cooked Phaseolus vulgaris L. A total of 104 compounds were detected by GC and GC/MS. Thereof, 76 compounds were identified for the first time in this species. The major differences between HS-SPME and SDE were found in the content of identified alcohols (23.62% SDE versus 62.20% SPME), terpenoids (39.15% SDE versus 2.45% SPME), heterocyclic compounds (13.78% SDE versus 1.21% SPME), hydrocarbons (2.22% SDE versus 13.87% SPME) and esters (0.98% SDE versus 12.98% SPME). The SPME technique was found to be useful for rapid and routine quality controls of thawed French beans, while SDE is favourable to study the entire set of flavour volatiles in the corresponding cooked samples.     

The inhibitory effect of the natural seed storage protein arcelin on the development of Acanthoscelides obtectus

To protect stored beans from attack by Acanthoscelides obtectus and other bruchids by non-toxic means of control, it is desirable to combine mutually compatible methods in an integrated approach. A combination of an optimal level of host–plant resistance based on the natural storage protein arcelin and a larval parasitoid has been suggested as a promising two-component strategy. While a dose–response to arcelin is evident in the bruchid Zabrotes subfasciatus, the effects of different arcelin concentrations on A. obtectus are still virtually unknown, even though they might be important for the success of the proposed integrated control system. The current investigation quantified the effect of different arcelin-based resistance levels of beans on the development of A. obtectus in a series of bioassays. Our findings show that all seven tested bean lines with markedly different levels of arcelin-based resistance against Z. subfasciatus consistently prolonged development of A. obtectus. Results provide clear evidence that arcelin acts as a growth inhibitor on first instar larvae. Furthermore, arcelin affected bruchid female fitness through its effect on body mass, which was significantly reduced on all arcelin-containing bean lines. This study demonstrates that, irrespective of its relative concentration, arcelin holds the potential to affect development of A. obtectus sufficiently to support the proposed two-component integrated pest management system.     

不同辐照剂量对红豆分离蛋白结构及特性的影响

采用Lowery法、ANS荧光探针法、圆二色光谱、荧光光谱等方法分别对不同辐照处理的红豆分离蛋白溶解度、表面疏水性、蛋白质二级、三级结构、流体动力学半径进行分析。结果表明:随着辐照剂量的增加,红豆分离蛋白的二级结构中α-螺旋结构向无规则卷曲结构的转变,Trp残基所处微环境极性先增强后减弱,这与其表面疏水性呈现正相关,蛋白颗粒大小随着辐照剂量的增加先减小后增大,在5 k Gy辐照剂量处理时达到最小,这与其溶解性呈现负相关。     

Enzymatic changes in pectic polysaccharides related to the beneficial effect of soaking on bean cooking time

BACKGROUND: Cooking time decreases when beans are soaked first. However, the molecular basis of this decrease remains unclear. To determine the mechanisms involved, changes in both pectic polysaccharides and cell wall enzymes were monitored during soaking. Two cultivars and one breeding line were studied. RESULTS: Soaking increased the activity of the cell wall enzymes rhamnogalacturonase, galactanase and polygalacturonase. Their activity in the cell wall was detected as changes in chemical composition of pectic polysaccharides. Rhamnose content decreased but galactose and uronic acid contents increased in the polysaccharides of soaked beans. A decrease in the average molecular weight of the pectin fraction was induced during soaking. The decrease in rhamnose and the polygalacturonase activity were associated (r = 0.933, P = 0.01, and r = 0.725, P = 0.01, respectively) with shorter cooking time after soaking. CONCLUSION: Pectic cell wall enzymes are responsible for the changes in rhamnogalacturonan I and polygalacturonan induced during soaking and constitute the biochemical factors that give bean cell walls new polysaccharide arrangements. Rhamnogalacturonan I is dispersed throughout the entire cell wall and interacts with cellulose and hemicellulose fibres, resulting in a higher rate of pectic polysaccharide thermosolubility and, therefore, a shorter cooking time. Copyright © 2011 Society of Chemical Industry     

Variability in the major lipid components of four market classes of dry edible beans

The lipid composition of dry edible beans (Phaseolus vulgaris L) was characterised and the variability between four US market classes (navy, dark red kidney, pinto and Black Turtle Soup) was determined. The total lipid content of the beans ranged from 1–8 to 2–6 g per 100 g dry weight. Triacylglycerol esterified sterified glucoside and phosphatidylcholine were identified as the major lipid class components of the neutral lipid, glycolipid and phospholipid fractions, respectively. The fatty acids were highly unsaturated: linolenic acid was the major fatty acid. Three sterols, campesterol, stigmasterol and β-sitosterol, were identified. The lipid and fatty acid contents of the bean classes were significantly ( P <0–05) different. Principal component analysis of the total lipid components resulted in the extraction of four factors, which accounted for 93.3% of the variability of the data set. These factors were characterised as the (I) fatty acid. (II) sterol. (III) lipid class, and (IV) oleic acid factors.