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Global concerns over environmental and social issues in agrifood value chains have increased and are reflected in a number of voluntary sustainability standards and regulatory initiatives. However, these initiatives are often based on poor knowledge of production realities, creating a disconnect between producing and consuming countries. Through narrative analysis, this paper reveals asymmetries in the responsibilities of the various actors participating in Ecuadorian banana value chains, providing clear problem- and solution-framings. Despite the broad range of actors interviewed, our analysis reveals convergence in two main narratives that reflect asymmetries amongst local actors in terms of their ability to participate, ability to maintain participation, and adaptation strategies in view of changing external factors. One narrative relates to sustainability adaptations, the cost of which is not shared among all value chain actors. This is combined with a downward trend in the price of bananas and the lack of a differentiated price to account for losses and costs arising from increasing sustainability standards. Another narrative reflects a value chain structure that threatens small-farm survival. It highlights the urgency of protecting small-farm activity by enforcing national regulation and developing new market segments/models that understand small-scale producer reality. Study results show that the multitude of standards is not seen as beneficial and that downstream actors rather wish for common minimum standards to reduce business costs. Compatibility between standards and local realities should be a priority for global sustainability standards adoption. Building on the problems and solution-framings of local value chain links, we give voice to local actors, and link their perceptions to existing literature and discursive politics while contributing to social transparency and addressing the democratic deficit in agrifood value chains.

Key message Calmodulin-like-proteins (CML) belong to a family of calcium-sensing proteins that are unique for plants and involved in many different developmental and stress-related reactions. In defense against herbivory, some pathogens and drought, CML37 acts as a positive and CML42 as a negative regulator, respectively. We provide evidence that both CMLs act antagonistically in the regulation of induced defense responses. A double knock-out line, cml37 x cml42, thus shows wild-type phenotypes upon all kind of stresses we used. Abstract A transient increase in the cytosolic calcium concentration is one of the first reactions that can be measured in plant cells upon abiotic as well as biotic stress treatments. These calcium signals are sensed by calcium binding proteins such as calmodulin-like proteins (CMLs), which transduce the sensed information into appropriate stress responses by interacting with downstream target proteins. In previous studies, CML37 has been shown to positively regulate the plants’ defense against both the insect herbivore Spodoptera littoralis and the response to drought stress. In contrast, CML42 is known to negatively regulate those two stress responses. Here, we provide evidence that these two CMLs act antagonistically in the regulation of induced responses directed against drought and herbivory stress as well as in the defense against the necrotrophic pathogen Alternaria brassicicola. Both CMLs shape the plant reactions by altering the phytohormone signaling. Consequently, the phytohormone-regulated production of defensive compounds like glucosinolates is also antagonistically mediated by both CMLs. The finding that CML37 and CML42 have antagonistic roles in diverse stress-related responses suggests that these calcium sensor proteins represent important tools for the plant to balance and fine-tune the signaling and downstream reactions upon environmental stress.

The discovery in tomato of systemin, the first plant peptide hormone1,2, was a fundamental change for the concept of plant hormones. Numerous other peptides have since been shown to play regulatory roles in many aspects of the plant life, including growth, development, fertilization and interactions with symbiotic organisms3-6. Systemin, an 18 amino acid peptide derived from a larger precursor protein 7 , was proposed to act as the spreading signal that triggers systemic defence responses observed in plants after wounding or attack by herbivores1,7,8. Further work culminated in the identification of a leucine-rich repeat receptor kinase (LRR-RK) as the systemin receptor 160 (SR160)9,10. SR160 is a tomato homologue of Brassinosteroid Insensitive 1 (BRI1), which mediates the regulation of growth and development in response to the steroid hormone brassinolide11-13. However, a role of SR160/BRI1 as systemin receptor could not be corroborated by others14-16. Here, we demonstrate that perception of systemin depends on a pair of distinct LRR-RKs termed SYR1 and SYR2. SYR1 acts as a genuine systemin receptor that binds systemin with high affinity and specificity. Further, we show that presence of SYR1, although not decisive for local and systemic wound responses, is important for defence against insect herbivory.

Ureases catalyze the hydrolysis of urea into ammonia and carbon dioxide and, thus, are involved in the metabolism and bioavailability of nitrogen. Ureases occur in plants, fungi, and bacteria. In plants, besides their enzymatic activity, ureases as proteins play a role in defense against insect and phytopathogenic fungi. Little is known about the regulation of urease in plants under stress and whether or not phytohormones may be involved. In this study, we addressed the regulation of ubiquitous urease (ubSBU) gene expression after phytohormone applications, insect herbivory, and mechanical damage in soybean (Glycine max cv. Williams 82). Stress-related phytohormones were applied. In addition, Spodoptera littoralis feeding and mechanical damage by MecWorm were performed. Ureolytic activity and transcripts for ubSBU and UreG were quantified. Roots and leaves showed the highest levels of ubSBU transcripts. The results show a significant increase of ubSBU transcripts upon jasmonic acid application and after herbivory, but downregulation after MecWorm treatment. UreG transcripts were downregulated after MecWorm, S. littoralis, and application of gibberellic acid, but upregulated by jasmonic acid. However, the ureolytic activities in leaves were influenced neither by phytohormones nor by herbivory and MecWorm. We conclude that the enzymatic activity of ureases is constitutive and basal levels of the enzyme are sufficient to perform the ureolytic activities in defense against insects and fungi. The defense role of ureases, which does not require the ureolytic activity, may underlie their differential regulation in response to different stress stimuli.

Wild edible fruits hold great potential for improving human diets, especially in agricultural societies of the developing world. In Africa, a well-known supplier of such fruits is the baobab (Adansonia digitata L., Malvaceae), one of the most remarkable trees of the world. Several studies in different African countries have highlighted this indigenous fruit tree as a priority species for domestication and expanded use. However, internationally available information on baobab in East Africa, particularly in Sudan and Kenya, remains scarce. This review aims to shed light on the ecology, diversity and current level of utilization of baobab in East Africa in order to facilitate domestication and conservation of the species. A list of priority research areas is provided at the end of the review to encourage further studies and investment in this unique plant taxon.

Carnivory, the ability of plants to attract, catch, kill and digest insects to obtain nutrients, has evolved independently several times in plant evolution. A comprehensive analysis of the genome, transcriptome and proteome of prey digestion in a pitcher plant shows how carnivory in plants is the product of convergent evolution.

The conjugates of 6-substituted 1-oxoindanoyl carboxylic acids with L-isoleucine are mimics of the plant hormone (+)-7-iso-JA-L-Ile (3) that controls and regulates secondary metabolism and stress responses. In order to generate ligands that can be used as hormone-like compounds possessing different biological activities, an efficient and short synthesis of 6-bromo-1-oxoindane-4-carboxylic acid opens a general route to 6-Br-1-oxoindanoyl L-isoleucine conjugate (Br-In-L-Ile) (9a) as a key intermediate for several bioactive 6-halogen-In-L-Ile analogs (7a, 8a, 10a). The 6-ethynyl-In-L-Ile analog (11a) might be a valuable tool to localize macromolecular receptor molecules by click-chemistry. The activities of In-Ile derivatives were evaluated by assays inducing the release of volatile organic compounds (VOCs) in lima bean (Phaseolus lunatus). Each compound showed slightly different VOC induction patterns. To correlate such differences with structural features, modeling studies of In-Ile derivatives with COI-JAZa/b/c co-receptors of P. lunatus were performed. The modeling profits from the rigid backbone of the 1-oxoindanonoyl conjugates, which allows only well defined interactions with the receptor complex.

A study to determine the species richness and spatial distribution of five meliponine bee species in three different habitats in the Kakamega forest was undertaken for the first time. Two forest (indigenous and mixed indigenous) and two grassland (with Eucalyptus spp. trees and indigenous trees) types, along with homesteads (in the vicinity of mixed indigenous forest and indigenous forest, respectively), were surveyed. Line transect methods were used in the nest survey in each habitat. The highest number of species was recorded in the indigenous forest, while no nest was discovered in the grassland with Eucalyptus spp. trees. The mean number of nests per transect was higher in homesteads followed by the indigenous forest. The nesting pattern of almost all species nesting in the indigenous forest, mixed indigenous forest (Meliponula bocandei [Spinola]) and grassland with indigenous tree species (Meliponula ferruginea [Lepeletier] reddish brown) was dispersed. The nesting pattern of M. ferruginea (reddish brown) and Hypotrigona gribodoi (Magretti) changed from a dispersed and random pattern, respectively, to a clumped nesting pattern when nesting in homesteads. The degree of nest clustering was low for M. ferruginea (reddish brown) and high for H. gribodoi. Differences in average nearest-neighbour distance were observed within species nesting in a dispersed or clumped pattern. This study reveals that habitat type in the Kakamega forest influences the species richness and nesting pattern of the five stingless bee species.

Pesticide handling practices have a strong bearing on the exposure of toxic effects to target and nontarget organism. A clear understanding of determinants of pesticide handling practices is a precondition in the design and implementation of policy intervention. To accomplish this, a household survey of 425 respondents was conducted in 2008. Majority of the farmers (85 %) had inappropriately handled pesticides, mainly through, unsafe storage (23 %), unsafe disposal of leftover in either sprays solutions, or rinsate and empty pesticide containers (40 %), failure to wear the required minimum protective gear (68 %), or overdosed pesticides (27 %). However, majority of those farmers were aware of the risks of pesticide use, with over 81 % expressing the view that pesticides have harmful effects on human health, livestock, beneficial arthropods, and on water. Econometric models showed that pesticide handling practices were significantly influenced by variation in record keeping, main source advice on pesticide use, toxicity of pesticide, and geographical location. Pesticide risk perception and negative impacts experiences had no association with handling practices. The study recommends policymakers to design effective, participatory, and location targeted outreach programmes, which deal specifically on promotion of record keeping and reduction in use of harmful pesticides.

Insect herbivory on plants is a complex incident consisting of at least two different aspects, mechanical damage and chemical factors. Only the combination of both is able to induce the respective plant defenses. Thus, diverse plant species emit volatile organic compounds (VOCs) in response to herbivory (HW), whereas mechanical damage inflicted as single wounding event (MD) does not induce increased VOC emissions. In contrast, a robotic worm (MecWorm, MW) allowed demonstrating that continuous mechanical damage is sufficient to induce volatile emission in Lima bean. However, the induced VOC blends remain characteristic for the respective stimulus. In order to identify putative differences in plant signaling leading to defenses, we compared time courses of early signals induced by wounding in Lima bean. Neither MD nor MW alone was able to induce plasma membrane (V m) depolarization, as observed after Spodoptera littoralis HW, but V m depolarization occurred in both treatments when used in combination with herbivore-derived oral secretions. A significant increase in cytosolic Ca2+ concentrations was observed only after HW, whereas MD and MW did not affect this second messenger. H2O2 was generated within 2–3 h after leaf damage by HW and MW, whereas MD induced only half of the H2O2 levels compared to the other treatments. Both HW and MW induced a marked accumulation of NO, but with distinct temporal patterns. NO production after MD followed the same trend but reached significantly lower values. The results indicate that chemical signals from the herbivores are responsible for the induction of the earliest signaling events. These changes appear to be characteristic for the reaction to herbivory.

Proline/hydroxyproline-rich glycoprotein (P/HRGP) level in pearl millet genotypes resistant to downy mildew increase after inoculation with the oomycete pathogen Sclerospora graminicola. Using purified P/HRGPs from pearl millet cell walls, polyclonal antibodies (Pab-P/HRGP) were raised in rabbit. Based on this antiserum, an enzyme immunoassay was developed that displays a linearity detection range from 0.01 to 10 μg P/HRGP. Western blot analysis, confirming the induction of three marker P/HRGPs in the infected resistant genotype, and immunocytochemical studies on P/HRGP localization either in epidermal peelings or in suspension-cultured cells demonstrated the specificity of the antiserum. Besides its characterization, Pab-P/HRGP was employed to screen various genotypes of pearl millet for fast, sensitive and specific detection of induced P/HRGPs upon infections. The results presented are discussed with presumed importance to downy mildew disease and the use of this new antiserum in pearl millet screening for disease resistance.

Plants recognize microbial pathogens by discriminating pathogen-associated molecular patterns from self-structures. We study the non-host disease resistance of soybean (Glycine max L.) to the oomycete, Phytophthora sojae. Soybean senses a specific molecular pattern consisting of a branched heptaglucoside that is present in the oomycetal cell walls. Recognition of this elicitor may be achieved through a beta-glucan-binding protein, which forms part of a proposed receptor complex. Subsequently, soybean mounts a complex defense response, which includes the increase of the cytosolic calcium concentration, the production of reactive oxygen species, and the activation of genes responsible for the synthesis of phytoalexins. We now report the identification of two mitogen-activated protein kinases (MAPKs) and one MAPK kinase (MAPKK) that may function as signaling elements in triggering the resistance response. The use of specific antisera enabled the identification of GmMPKs 3 and 6 whose activity is enhanced within the signaling pathway leading to defense reactions. Elicitor specificity of MAPK activation as well as the sensitivity against inhibitors suggested these kinases as part of the beta-glucan signal transduction pathway. An upstream GmMKK1 was identified based on sequence similarity to other plant MAPKKs and its interaction with the MAPKs was analyzed. Recombinant GmMKK1 interacted predominantly with GmMPK6, with concomitant phosphorylation of the MAPK protein. Moreover, a preferential physical interaction between GmMKK1 and GmMPK6 was demonstrated in yeast. These results suggest a role of a MAPK cascade in mediating beta-glucan signal transduction in soybean, similar to other triggers that activate MAPKs during innate immune responses in plants.

Rural people in Africa periodically rely on wild fruits to supplement their diet and to generate cash income. However, scientific evidence on the economics of using indigenous fruit tree (IFT) products is scarce. The objective of the study was to fill in some of the gaps for which farm-household surveys were conducted in Zimbabwe during 1999–2000. Gross margins and returns to labour in collection, use and sale of products of Uapaca kirkiana (Muell. Arg., Wild Loquat), Strychnos sp. (S. cocculoides (Baker) and S. spinosa (Lam.), Monkey Orange) and Parinari curatellifolia (Planch. ex. Benth., Fever Tree) were compared with other farming activities. A random sample of over three hundred households in the Murehwa Communal and the Takawira Resettlement Areas was interviewed to gather income and expenditure data. Additionally, income, expenditure and labour allocation of 39 households were closely monitored for one year. Results indicated that the majority of rural households benefited from consumption and sale of indigenous (IF), although the extent varied among households. Within the households, children were the main consumers of fruits. Marketing of IF are carried out by women who used the receipts to purchase household goods. While U. kirkiana fruits were more important in generating cash income than others, fruits of P. curatellifoliawere important for home consumption during periods of food shortages. The gross margins for collection of IFT products were lower than for livestock and crop production. However, returns to labour from collection and use of IFT products were considerably greater than from other activities including gardening and livestock rearing. The study indicates that collection of IFT products is an efficient labour allocation strategy in Zimbabwe.

Due to the involvement of calcium as a main second messenger in the plant signaling pathway, increasing interest has been focused on the calcium signatures supposed to be involved in the patterning of the specific response associated to a given stimulus. In order to follow these signatures we described here the practical approach to use the non-invasive method based on the aequorin technology. Besides reviewing the advantages and disadvantages of this method we report on results showing the usefulness of aequorin to study the calcium response to biotic (elicitors) and abiotic stimuli (osmotic shocks) in various compartments of plant cells such as cytosol and nucleus.

Transgenic soybean (Glycine max L.) cells expressing aequorin were used to monitor changes in cytosolic Ca2+ concentrations in response to treatment with fungal elicitors. After an apparent lag phase of about 60 s, both chitin fragments and β-glucan elicitors caused a rapid increase in cytosolic Ca2+ concentration, which peaked within 2–2.5 min of treatment. The Ca2+ concentration then decreased and reached the basal level after about 5 min in the case of the treatment with chitin fragments, while a second rise in the Ca2+ concentration with a maximum occurring after about 7–8 min was observed in the case of β-glucan treatment. Calibration of the signals showed that the elicitors enhanced the cytosolic Ca2+ concentration from resting concentrations as low as 0.1 lM to highest levels of about 2 lM. Dose-response experiments showed that the concentration of elicitors giving a Ca2+ response at the 50% level was 0.4 nM for the chitin fragment and 28 lM and 72 lM, respectively, for a synthetic hepta-β-glucoside and a fungal β-glucan fraction. The β-glucan- or N,N′,N′′,N′′′-tetraacetyl chitotetratose (CH4)-induced Ca2+ signals were inhibited by both the Ca2+ chelator 1,2-bis-(2-aminophenoxy) ethane-N,N,N′,N′-tetraacetic acid (BAPTA) and by the Ca2+-channel inhibitor La3+. Neomycin, whose target in plant cells has not yet been clearly identified, reduced predominantly the expression of the second peak of the biphasic Ca2+ curve following β-glucan treatment. Bacterial cyclic β-glucans known to suppress β-glucan-induced phytoalexin production were also found to function as a suppressor for the Ca2+ response that was elicited by the fungal β-glucans. The results clearly show that the increase in the cytosolic Ca2+ concentration is an early and rapid event in the elicitor-sensing mechanism of soybean cells, and is probably connected with the subsequent activation of defence responses.

Plants successfully use inducible defence mechanisms to combat potential pathogens. Elicitors are signaling compounds that stimulate any of such defence responses. Recent progress in the isolation of pure elicitors has made possible investigations on elicitor-binding proteins which might function as receptors in signal transduction pathways that ultimately activate the defences. The elicitor-binding sites studied so far show a high degree of ligand specificity, as do the candidate binding proteins identified for some of the ligands. Following elicitor perception, a number of rapid reactions are detectable in plant cells, including enhanced ion fluxes across the plasma membrane, formation of reactive oxygen intermediates, changes in protein phosphorylation, and lipid oxidation. Intriguing questions arising from these observations are whether the elicitor-binding proteins constitute receptors in plant defence signaling and whether any of the rapid events participate in signal transduction during defence activation.

Pancreatic abscess is one of the infectious complications of acute pancreatitis. It is a collection principally containing pus, but it may also contain variable amounts of semisolid necrotic debris. Most of these abscesses evolve from the progressive liquefaction of necrotic pancreatic and peripancreatic tissues, but some arise from infection of peripancreatic fluid or collections elsewhere in the peritoneal cavity. Included also are abscesses found after surgical débridement and drainage of pancreatic necrosis. Although open surgical treatment of infected necrosis is the established treatment of choice, percutaneous drainage of abscesses is successful in some circumstances. We used percutaneous catheter drainage in 39 patients during 1987-1995. Only 9 of 29 (31%) attempts at primary therapy were successful; 2 patients died, and 18 required subsequent surgical drainage. On the other hand, 14 of 14 patients with recurrent or residual abscesses after surgical drainage were successfully drained percutaneously. Percutaneous catheter drainage of pancreatic abscesses may be useful for initial stabilization of septic patients, drainage of further abscesses after surgical intervention (especially when access for reoperation will be difficult), associated abscesses remote from the pancreas, and selected unilocular collections at a sufficient interval after necrotizing pancreatitis to have allowed essentially complete liquefaction.

Ultrahigh-molecular dextran (500 000 DA) has been shown to prevent pancreatic necrosis when given 30 min after induction of pancreatitis. This study should clarify the following: (a) are dextrans still effective after prolongation of the therapy-free interval? (b) what is the impact of the molecular weight of the dextrans? and (c) is their effect influenced by the dextran concentration or by the addition of hypertonic saline? Acute pancreatitis was induced in 70 male dextran-tolerant Wistar rats using intraductal bile-salt infusion and intravenous hyperstimulation. After 3 h, animals were assigned to one of seven groups (n=10 per group) receiving either Ringer solution or different dextrans (10%) including 70 000 Da (DEX-70), 160 000 Da (DEX-160), 300 000 Da (DEX-300) or 500 000 Da (DEX-500). Additional groups included DEX-70 (6%) and DEX-70 (10%) in combination with hypertonic NaCl (7.5%) (HHS-70). Ringer solution was given at 24 ml/kg and all dextrans at 8 ml/kg. Trypsinogen activation peptides (TAP) were quantified in ascites and acinar necrosis after death or sacrifice at 9 h. As an index of less pathological trypsinogen activation, the mean TAP levels in ascites were significatly lower in DEX-70 and DEX-160 compared to Ringer controls (p

A case is presented of a tibial plateau fracture after previous anterior cruciate ligament reconstruction using patellar tendon autograft. The tibial plateau fracture occurred through the transosseous tibial tunnel and followed a torsional injury to the involved extremity. The stress riser effect of the transosseous tibial tunnel and the anatomic location of the cortical defect probably facilitated development of the fracture. Minimally invasive fixation of the fracture was effective in preserving knee stability without need for revision anterior cruciate ligament reconstruction.

The production of antimicrobial phytoalexins is one of the best-known inducible defence responses following microbial infection of plants or treatment with elicitors. In the legume soybean (Glycine max L.), 1,3-1,6-β-glucans derived from the fungal pathogen Phytophthora sojae have been identified as potent elicitors of the synthesis of the phytoalexin, glyceollin. Recently it has been reported that during symbiotic interaction between soybean and the nitrogen-fixing bacterium Bradyrhizobium japonicum USDA 110 the bacteria synthesize cyclic 1,3-1,6-β-glucans. Here we demonstrate that both the fungal and the bacterial β-glucans are ligands of β-glucan-binding sites which are putative receptors for the elicitor signal compounds in soybean roots. Whereas the fungal β-glucans stimulate phytoalexin synthesis at low concentrations, the bacterial cyclic 1,3-1,6-β-glucans appear to be inactive even at relatively high concentrations. Competition studies indicate that increasing concentrations of the bacterial 1,3-1,6-β-glucans progressively inhibit stimulation of phytoalexin synthesis in a bioassay induced by the fungal 1,3-1,6-β-glucans. Another type of cyclic β-glucan, a 1,2-β-glucan from Rhizobium meliloti, that does not nodulate on soybean, seems to be inactive as elicitor and as ligand of the β-glucan-binding sites. These results may indicate a novel mechanism for a successful plant-symbiont interaction by suppressing the plant's defence response.