Direct Defense or Ecological Costs: Responses of Herbivorous Beetles to Volatiles Released by Wild Lima Bean (Phaseolus lunatus)

In response to feeding damage, Lima bean releases herbivore-induced plant volatiles (HIPV), which are generally assumed to attract carnivorous arthropods as an indirect defense. While many studies have focused on such tritrophic interactions, few have investigated effects of HIPV on herbivores. I used natural herbivores of wild Lima bean and studied their responses to jasmonic acid-induced plants in an olfactometer and in feeding trials. Both Cerotoma ruficornis and Gynandrobrotica guerreroensis (Chrysomelidae) significantly preferred control plants to induced ones in the olfactometer, and they avoided feeding on induced plants. In contrast, Curculionidae significantly preferred HIPV of the induced plant to those of the control in one plant pair and did not choose in the case of a second pair. In feeding trials, no choice occurred in the first plant pair, while control leaves were preferred in the second. Release of HIPV deterred Chrysomelid herbivores and, thus, acted as a direct defense. This may be an important addition to indirect defensive effects. Whether or not HIPV released by induced plants attracted herbivorous Curculionidae, thus incurring ecological costs, varied among plants. Such differences could be related to various HIPV blends released by individual plants.     

Quantitative Effects of Leaf Area Removal on Indirect Defense of Lima Bean (Phaseolus lunatus) in Nature

Plants employ a diverse array of defensive traits against multiple enemies. While many plant defenses are well-studied, quantitative feedback effects of leaf area loss on the expression of defensive traits remain little understood. Extrafloral nectar (EFN; an indirect defense acting via the attraction of carnivorous arthropods) is generally considered ‘cheap’ as it is composed mainly of photosynthates. However, to what extent EFN secretion is related to the amount of intact photosynthetic leaf area is unknown. In this study, we measured the production of EFN, ant attraction, and herbivore damage in response to a gradient of leaf area removal in wild lima bean (Phaseolus lunatus) under natural conditions in southern Mexico. EFN production and ant recruitment were significantly decreased with increasing leaf area removal. Consequently, EFN production was inversely correlated with leaf area loss, which suggests that EFN is metabolically more expensive than previously thought. Further, we found increased herbivory in plants with reduced EFN secretion indicating additive negative feedback effects of leaf area loss. Our study is one of the first showing a quantitative negative impact of leaf damage on EFN secretion—one of the most widely distributed defensive traits in the plant kingdom.     

Co-Variation of Chemical and Mechanical Defenses in Lima Bean (Phaseolus lunatus L.)

Plants usually express multiple chemical and mechanical defenses simultaneously. The interplay of these defenses is still poorly understood, as predictions range from negative associations such as allocation tradeoffs to positive correlations forming synergistic defense syndromes. Surprisingly, little empirical evidence exists on the co-variation of multiple plant defenses. In the present study, we analyzed different genotypes of lima bean (Phaseolus lunatus L.) for the expression of two direct chemical defenses [cyanogenic potential (constitutive), polyphenol oxidase activity (inducible)], two indirect chemical defenses [volatiles (VOCs) and extrafloral nectar (EFN; both inducible)] and a constitutive mechanical defense (hook-shaped trichomes). While the occurrence of trichomes was positively correlated with cyanogenesis, these traits showed a tradeoff with polyphenol oxidase activity, release of VOCs, and secretion of EFN. Hook-shaped trichomes were abundantly present in four of 14 genotypes investigated, and were found only in one monophyletic group of an AFLP-based tree, thus indicating a single evolutionary origin within the species. Our findings show that different lima bean genotypes express either one of two defense systems: 1) high constitutive defense via cyanogenesis and trichomes or 2) high inducible defense via VOCs, EFN, and PPO activity.     

Oviposition Choice of Mexican Bean Beetle (Epilachna varivestis) Depends on Host Plants Cyanogenic Capacity

The choice of insect females as to where to lay their eggs strongly affects progeny survival and, thus, fitness. We conducted choice experiments with female Mexican bean beetles, which were offered lima bean plants differing in their cyanogenic capacity (HCNc), i.e., in the intensity of hydrogen cyanide release per time unit from damaged plant tissue. Females preferred to lay their eggs on plants with low HCNc. In contrast, the mere concentration of cyanide-containing precursors (the cyanogenic potential, HCNp) did not affect oviposition choices. Plant cyanogenesis occurs after tissue damage, which brings specific β-glucosidases in contact with their substrates, cyanogenic glycosides, from which they are separated by compartmentation in the intact plant tissue. Plants commonly store toxic compounds in an inactive form. Our results demonstrate that for cyanogenesis, which is widespread in plants, it is the toxic product itself rather than the precursor that affects oviposition choices of a specialized herbivore.     

Symptomless Endophytic Fungi Suppress Endogenous Levels of Salicylic Acid and Interact With the Jasmonate-Dependent Indirect Defense Traits of Their Host,Lima Bean (Phaseolus lunatus)

Symptomless ‘type II’ fungal endophytes colonize their plant host horizontally and exert diverse effects on its resistance phenotype. Here, we used wild Lima bean (Phaseolus lunatus) plants that were experimentally colonized with one of three strains of natural endophytes (Bartalinia pondoensis, Fusarium sp., or Cochliobolus lunatus) to investigate the effects of fungal colonization on the endogenous levels of salicylic acid (SA) and jasmonic acid (JA) and on two JA-dependent indirect defense traits. Colonization with Fusarium sp. enhanced JA levels in intact leaves, whereas B. pondoensis suppressed the induction of endogenous JA in mechanically damaged leaves. Endogenous SA levels in intact leaves were significantly decreased by all strains and B. pondoensis and Fusarium sp. decreased SA levels after mechanical damage. Colonization with Fusarium sp. or C. lunatus enhanced the number of detectable volatile organic compounds (VOCs) emitted from intact leaves, and all three strains enhanced the relative amount of several VOCs emitted from intact leaves as well as the number of detectable VOCs emitted from slightly damaged leaves. All three strains completely suppressed the induced secretion of extrafloral nectar (EFN) after the exogenous application of JA. Symptomless endophytes interact in complex and strain-specific ways with the endogenous levels of SA and JA and with the defense traits that are controlled by these hormones. These interactions can occur both upstream and downstream of the defense hormones.     

Biochemical and nutritional value of seeds of the lima bean (Phaseolus lunatus) in comparison with those of the common bean (Phaseolus vulgaris)

Composition in nutrients and antinutritional factors, digestibility and growth in rats fed diets prepared with raw and cooked beans of Ph. vulgaris, cultivar "Tacarigua", and Ph. lunatus cultivar "Tapiramo", are compared. Grains from both cultivars are similar in appearance, taste, nutritional value, and acceptability. Protein and phosphorus contents were greater in Ph. vulgaris than in Ph. lunatus seeds. The chemical score and availability of lysine were better in Ph. lunatus. Diets prepared with raw beans from Ph. lunatus resulted non toxic for the rats during a 12-day period of feeding. All rats fed with raw beans from Ph. Vulgaris died in the same period of time. Protein efficiency was better with cooked beans of Ph. lunatus. The cultivar "Tapiramo" (Ph. lunatus) is recommended for autoconsumption by small farmers.     

Salinity-Induced Variation in Biochemical Markers Provides Insight into the Mechanisms of Salt Tolerance in Common (Phaseolus vulgaris) and Runner (P. coccineus) Beans

The evaluation of biochemical markers is important for the understanding of the mechanisms of tolerance to salinity of Phaseolus beans. We have evaluated several growth parameters in young plants of three Phaseolus vulgaris cultivars subjected to four salinity levels (0, 50, 100, and 150 mM NaCl); one cultivar of P. coccineus, a closely related species reported as more salt tolerant than common bean, was included as external reference. Biochemical parameters evaluated in leaves of young plants included the concentrations of ions (Na⁺, K⁺, and Cl⁻), osmolytes (proline, glycine betaine, and total soluble sugars), and individual soluble carbohydrates. Considerable differences were found among cultivars, salinity levels, and in their interaction for most traits. In general, the linear component of the salinity factor for the growth parameters and biochemical markers was the most important. Large differences in the salinity response were found, with P. vulgaris cultivars “The Prince” and “Maxidor” being, respectively, the most susceptible and tolerant ones. Our results support that salt stress tolerance in beans is mostly based on restriction of Na⁺ (and, to a lesser extent, also of Cl⁻) transport to shoots, and on the accumulation of myo-inositol for osmotic adjustment. These responses to stress during vegetative growth appear to be more efficient in the tolerant P. vulgaris cultivar “Maxidor”. Proline accumulation is a reliable marker of the level of salt stress affecting Phaseolus plants, but does not seem to be directly related to stress tolerance mechanisms. These results provide useful information on the responses to salinity of Phaseolus.     

Introgression Between Cultivars and Wild Populations of Momordica charantia L. (Cucurbitaceae) in Taiwan

The landrace strains of Momordica charantia are widely cultivated vegetables throughout the tropics and subtropics, but not in Taiwan, a continental island in Southeast Asia, until a few hundred years ago. In contrast, the related wild populations with smaller fruit sizes are native to Taiwan. Because of the introduction of cultivars for agricultural purposes, these two accessions currently exhibit a sympatric or parapatric distribution in Taiwan. In this study, the cultivars and wild samples from Taiwan, India, and Korea were collected for testing of their hybridization and evolutionary patterns. The cpDNA marker showed a clear distinction between accessions of cultivars and wild populations of Taiwan and a long divergence time. In contrast, an analysis of eight selectively neutral nuclear microsatellite loci did not reveal a difference between the genetic structures of these two accessions. A relatively short divergence time and frequent but asymmetric gene flows were estimated based on the isolation-with-migration model. Historical and current introgression from cultivars to wild populations of Taiwan was also inferred using MIGRATE-n and BayesAss analyses. Our results showed that these two accessions shared abundant common ancestral polymorphisms, and the timing of the divergence and colonization of the Taiwanese wild populations is consistent with the geohistory of the Taiwan Strait land bridge of the Last Glacial Maximum (LGM). Long-term and recurrent introgression between accessions indicated the asymmetric capacity to receive foreign genes from other accessions. The modern introduction of cultivars of M. charantia during the colonization of Taiwan by the Han Chinese ethnic group enhanced the rate of gene replacement in the native populations and resulted in the loss of native genes.     

Microsatellite Variation in the Most Devastating Beetle Pests (Coleoptera: Curculionidae) of Agricultural and Forest Crops

Weevils, classified in the family Curculionidae (true weevils), constitute a group of phytophagous insects of which many species are considered significant pests of crops. Within this family, the red palm weevil (RPW), Rhynchophorus ferrugineus, has an integral role in destroying crops and has invaded all countries of the Middle East and many in North Africa, Southern Europe, Southeast Asia, Oceania, and the Caribbean Islands. Simple sequence repeats (SSRs), also termed microsatellites, have become the DNA marker technology most applied to study population structure, evolution, and genetic diversity. Although these markers have been widely examined in many mammalian and plant species, and draft genome assemblies are available for many species of true weevils, very little is yet known about SSRs in weevil genomes. Here we carried out a comparative analysis examining and comparing the relative abundance, relative density, and GC content of SSRs in previously sequenced draft genomes of nine true weevils, with an emphasis on R. ferrugineus. We also used Illumina paired-end sequencing to generate draft sequence for adult female RPW and characterized it in terms of perfect SSRs with 1–6 bp nucleotide motifs. Among weevil genomes, mono- to trinucleotide SSRs were the most frequent, and mono-, di-, and hexanucleotide SSRs exhibited the highest GC content. In these draft genomes, SSR number and genome size were significantly correlated. This work will aid our understanding of the genome architecture and evolution of Curculionidae weevils and facilitate exploring SSR molecular marker development in these species.     

Effect of the seed coat on the hardening of common beans (Phaseolus vulgaris)

Samples of cotyledons and whole black beans (Phaseolus vulgaris), Tamazulapa variety were stored during six weeks at 37 degrees C and 90% relative humidity to establish chemical and physical changes which occur during storage, and to determine the role played by the seed coat in the hard-to-cook phenomenon. After the storage period, samples of whole beans were divided in two subsamples, with and without the seed coat. These two samples and the cotyledons were analyzed for cooking time, water absorption, dietary fiber, tannic acid, soluble pectins and phytic acid. Cooking time of the whole beans increased from 99 to more than 480 minutes in the six-weeks period; for the cotyledons this value increased from 45 to 111 minutes. Cooking time of the dehulled bean, stored as whole bean, increased from 45 to 111 minutes. Cooking time of the dehulled bean, stored as whole bean, increased from 45 to 103 minutes. Water absorption in the whole beans and the cotyledons decreased, although in the cotyledons it was higher, due perhaps to the great absorption capacity to the seed coat. No changes were observed in the dietary fiber content of the cotyledons nor in the beans dehulled after storage. However, in the whole grains neutro-detergent fiber decreased, while acid detergent fiber, cellulose and lignin did not present significant changes. On the other hand, soluble pectates decreased in the whole bean and in the cotyledons; nevertheless the tannin content (as tannic acid) decreased only in the whole beans (from 3.28 to 1.64 mg/g). The data obtained suggest that the seed coat plays a significant role in the hard-to-cook process of hardening of the bean, before and during storage.     

Effect of Roasting on Physicochemical Properties of Wild Almonds (Amygdalus scoparia)

Roasting enhances sensory quality of wild almonds (Amygdalus scoparia). The aim of the study was to evaluate the use of microwaves (480 W for 3 or 4 min) in roasting of wild almonds in comparison with traditional Spanish (165 °C for 20 min) and Iranian (soaking in 20 % NaCl in water for 30 min, drying at 60 °C for 2 h and roasting at 135 °C for 20 min) hot‐air processes. The influence of roasting wild almonds on moisture and oil contents, crispness, fatty acid profile, volatile compounds, and odour intensity was investigated. Roasting causes changes in appearance, texture and flavour, due to dehydration, browning, lipid oxidation, and diverse structural changes. The moisture content and hardness of the samples significantly decreased with all roasting methods. Roasting resulted in higher amounts of characteristics aroma compounds and only microwave roasting increased the oil content. The final recommendation is that microwave roasting at 480 W for 4 min led to roasted almonds of high physicochemical [dark and intense colour (L*44.9, a*8.4, and b*19.6), the highest content of total volatile compounds (132 mg kg^?1), 85.2 % of unsaturated fatty acids], and sensory (high intensity of “roasted almond” aroma) quality. Microwaves can be used for roasting wild almond as a quick, safe, and economical method.     

Effect of pectinase and cellulase addition on in vitro digestibility of common bean (Phaseolus vulgaris)

Effect of commercial pectinase and cellulase addition on in vitro digestibility of two common bean (Phaseolus vulgaris) varieties, black (Brunca) and red (Chirripó), was measured. Constant conditions of pH (6.3-6.4), time (60 min), and temperature (40 degrees C) were held, and three enzyme concentrations were tested: 0.25%, 0.5% and 1.0% m/m. In vitro digestibility increases for black beans were 6.9%; 9.5% and 12.3% (p < 0.05), and for red beans were 8.9%; 10.2% and 12.9% (p < 0.05), with increasing pectinase concentration. Effects of cellulase were dependent upon both, enzyme concentration and bean variety. In vitro digestibility of red beans increased by 5.7%; 9.2% and 12.0% with increasing cellulase concentration; digestibility of black beans increased by less than 5%. No significant difference (p > 0.05) in general acceptance of enzyme treated beans (black or red) or nontreated beans was noted.     

Performance of an Herbivorous Leaf Beetle (Phratora vulgatissima) on Salix F2 Hybrids: the Importance of Phenolics

The genotype of the plant determines, through the expression of the phenotype, how well it is suited as food for herbivores. Since hybridization often results in profound genomic alterations with subsequent changes in phenotypic traits, it has the potential to significantly affect plant-herbivore interactions. In this study, we used a population of F2 hybrids that originated from a cross between a Salix viminalis and a Salix dasyclados genotype, which differed in both phenolic content and resistance to the herbivorous leaf beetle Phratora vulgatissima. We screened for plants that showed a great variability in leaf beetle performance (i.e., oviposition and survival). By correlating leaf phenolics to the response of the herbivores, we evaluated the importance of different phenolic compounds for Salix resistance to the targeted insect species. The performance of P. vulgatissima varied among the F2 hybrids, and two patterns of resistance emerged: leaf beetle oviposition was intermediate on the F2 hybrids compared to the parental genotypes, whereas leaf beetle survival demonstrated similarities to one of the parents. The findings indicate that these life history traits are controlled by different resistance mechanisms that are inherited differently in the hybrids. Salicylates and a methylated luteolin derivative seem to play major roles in hybrid resistance to Phratora vulgatissima. Synergistic effects of these compounds, as well as potential threshold concentrations, are plausible. In addition, we found considerable variation in both distributions and concentrations of different phenolics in the F2 hybrids. The phenolic profiles of parental genotypes and F2 hybrids differed significantly (e.g., novel compounds appeared in the hybrids) suggesting genomic alterations with subsequent changes in biosynthetic pathways in the hybrids.     

Effect of various solvents on the extraction of protein fractions of beans (Phaseolus vulgaris)

A study was carried out to determine the effect of different solvents on the extraction of protein fractions in beans. Black bean protein was extracted with the following solvents: distilled water, 0.01 M sodium hydroxide, 0.05 M sodium chloride, and 70% ethanol. By using each solvent under different conditions, it was possible to establish the optimum ones for the best extraction and fractionation of proteins from leguminous seeds. These conditions were the following: one hour agitation at room temperature, three successive extractions with the same solvent, and a ratio of solid to solvent of 1:20 W/V. The effect of 24 different sequences of solvents upon the extraction of protein was also investigated. From the extraction point of view, the best sequence of solvents for extracting the protein was that where NaOH constituted the first solvent used; this sequence, however, has the disadvantage of extracting all the protein from the seed, making it impossible to separate other protein fractions by another solvent. If the purpose of the extraction is to separate different protein fractions, the best sequence of solvents is distilled water or sodium chloride in the first place, followed by ethanol and sodium hydroxide. The need for using standardized methodology for the fractionation of protein from seeds in order to obtain comparable data between research laboratories is emphasized.     

HRT对IC反应器运行性能的影响

为改善厌氧内循环反应器(IC反应器)的运行性能,在水力停留时间(HRT)分别为8.6 h、10 h、12 h、14 h、20 h的情况下,对系统运行性能进行研究。在适当的范围内,随着HRT的增加,反应器内部始终维持着良好的厌氧环境;系统COD去除率总体呈现逐渐增加的趋势,且始终维持在90%以上;系统产气总量和甲烷产量均呈现先增加后降低的趋势,在HRT为10h时,系统产气总量及甲烷产量均达到最大值277L/d和162 L/d,反应器的运行效果最佳。     

纳米SiO_2对P(MMA-co-MAA)自脆裂剥离性能的影响

将硅烷偶联剂KH560改性的纳米二氧化硅(SiO_2)与甲基丙烯酸甲酯-甲基丙烯酸共聚物[P(MMA-coMAA)]乳液进行复配。采用红外光谱(FTIR)、热重(TG)、X射线衍射仪(XRD)、扫描电镜(SEM)对复合乳液的结构和性能进行了测定。结果表明,加入纳米SiO_2后使得P(MMA-co-MAA)的聚集态结构发生了改变,造成乳液自脆化形貌发生变化。主要表现为:随着纳米SiO_2含量的增加,脆片有变大的趋势,同时,收缩卷曲更加明显,提高了P(MMA-co-MAA)的自脆裂剥离性能。这种性能在去除设备表面的放射性污染的废物机械回收中更具备优势。     

Genetic Variation of the Endangered Gentiana lutea L. var. aurantiaca (Gentianaceae) in Populations from the Northwest Iberian Peninsula

Gentiana lutea L. (G. lutea L.) is an endangered plant, patchily distributed along the mountains of Central and Southern Europe. In this study, inter-simple sequence repeat (ISSR) markers were used to investigate the genetic variation in this species within and among populations of G. lutea L. var. aurantiaca of the Cantabrian Mountains (Northwest Iberian Peninsula). Samples of G. lutea L. collected at different locations of the Pyrenees and samples of G. lutea L. subsp. vardjanii of the Dolomites Alps were also analyzed for comparison. Using nine ISSR primers, 106 bands were generated, and 89.6% of those were polymorphic. The populations from the Northwest Iberian Peninsula were clustered in three different groups, with a significant correlation between genetic and geographic distances. Gentiana lutea L. var. aurantiaca showed 19.8% private loci and demonstrated a remarkable level of genetic variation, both among populations and within populations; those populations with the highest level of isolation show the lowest genetic variation within populations. The low number of individuals, as well as the observed genetic structure of the analyzed populations makes it necessary to protect them to ensure their survival before they are too small to persist naturally.     

碳包覆对LiFe0.8Mn0.2PO4性能的影响

为保证锂离子电池的正极材料磷酸亚铁锂具有优良的电化学性能,采用了碳包覆和锰元素掺杂的方法提高初始容量和充放电性能.以醋酸锰为Mn源,葡萄糖为C源,采用高温固相法合成碳包覆的LiFe0.8Mn0.2PO4/C,用XRD、恒流充放电研究了材料的结构和电化学性能.结果表明:包覆后的材料仍然具有橄榄石型晶体结构,并且包覆碳后材...     

Effect of Spatial Variation on Defensive Substances of Constrictotermes Cyphergaster Soldiers (Blattaria,Isoptera)

Journal of Chemical Ecology - The composition of chemical weaponry of termite soldiers show interspecific and intraspecific variation. However, spatial effects on the qualitative and quantitative...