Decomposition and nutrient release of green manure biomass in a passion fruit orchard in the brazilian semiarid region.

Green manure decomposition and nutrient recycling improve soil quality and productivity of different crops, but information on irrigated fruit orchards in the Brazilian semi-arid region is still scarce. Decomposition and nitrogen, phosphate, and potassium release from the cut biomass of three green manure legumes (sunn hemp, pigeon pea and jack bean) placed in litterbags, and spontaneous vegetation grown for 90 days in the rows of a passion fruit orchard were followed for 150 days. Biomasses decreased exponentially, reaching 12 (sunn hemp) to 25% (jack beans and spontaneous vegetation) after 150 days. K was rapidly released (< 21 and 4% of the original content remaining after 7 and 150 days, respectively), contrasting with more than half of the P and one third of the N remaining after 150 days. The amounts released were more influenced by the amounts of biomass produced (sunn hemp, 1583); (Jack bean 5152 kg ha-1); (Pigeon pea 822 kg ha-1); (Spontaneous plants 3175 kg ha-1); (spontaneous legumes 744 kg ha-1) than by variation in decomposition proportions among species. N release represented a liquid input to the soil, since more than 80% of the green manure and spontaneous vegetation contents came from N2-symbiotic fixation. Therefore, green manure is an effective technique to incorporate N and recycle K and P in irrigated orchards in the Brazilian semi-arid region.

Organic fertilization and mycorrhization increase copper phytoremediation by Canavalia ensiformis in a sandy soil.

Organic fertilization and mycorrhization can increase the phytoremediation of copper-contaminated soils. The time of vermicomposting alters the properties of vermicompost, which can affect copper's availability and uptake. Therefore, this study sought to evaluate the effect of different organic fertilizers and mycorrhization on copper-contaminated soil phytoremediation. The soil was contaminated with 100 mg Cu kg-1 dry soil and received mineral fertilizer (MIN), bovine manure (CM), and vermicompost produced in 45 days (V45) or 120 days (V120), all in doses equivalent to 40 mg kg-1 dry soil of phosphorus. Half of the jack bean (Canavalia ensiformis) plants were inoculated with the arbuscular mycorrhizal fungus Rhizophagus clarus. At plant flowering, the dry mass and concentrations of Cu, Zn, Mn, Ca, Mg, P, and K in the soil, solution, and plant tissue were determined, in addition to mycorrhizal colonization, nodulation, photosynthetic pigments, and oxidative stress enzyme activity. Organic fertilization increased plant growth and copper accumulation in aerial tissues. These effects were more evident with the V120, making it suitable for use in copper phytoextraction. Mycorrhization increased root and nodule dry mass, making it recommended for phytostabilization. C. ensiformis nodulation in Cu-contaminated soils depends on vermicompost fertilization and mycorrhization. Hence, the copper phytoremediation by C. ensiformis is increased by using organic fertilization and mycorrhization.

Computational Strategies Targeting Inhibition of Helicobacter pylori and Cryptococcus neoformans Ureases.

Helicobacter pylori and Cryptococcus ssp. are pathogenic ureolytic microorganisms that cause several disorders in the host organism and, in severe cases, lead to death. Both infections have the urease enzyme as a key virulence factor since they use its ability to produce ammonia to soften the inhospitable pH to which they are subjected. In this review, we describe two ureases as possible molecular targets for drug discovery and provide insights for developing potent inhibitors against ureases from these pathogenic microorganisms through computer-aided drug discovery approaches, such as structure-based drug design (SBDD) and structure-activity relationship (SAR). The SAR studies have indicated several essential subunits and groups to be present in urease inhibitors that are critical for inhibitory activity against H. pylori or Cryptococcus spp. Since the threedimensional structure of C. neoformans urease has yet to be determined experimentally, the plant urease of Canavalia ensiformis was used in this study due to its structural similarity. Therefore, in the SBDD context, FTMap and FTSite analyses were performed to reveal characteristics of the urease active sites in two protein data bank files (4H9M, Canavalia ensiformis, and 6ZJA, H. pylori). Finally, a docking-based analysis was performed to explore the best inhibitors described in the literature to understand the role of the ligand interactions with the key residues in complex ligand-urease stabilization, which can be applied in the design of novel bioactive compounds.

Canavalia ensiformis lectin induced oxidative stress mediate both toxicity and genotoxicity in Drosophila melanogaster.

Mannose/glucose-binding lectin from Canavalia ensiformis seeds (Concanavalin A - ConA) has several biological applications, such as mitogenic and antitumor activity. However, most of the mechanisms involved in the in vivo toxicity of ConA are not well known. In this study, the Drosophila melanogaster model was used to assess the toxicity and genotoxicity of different concentrations of native ConA (4.4, 17.5 and 70 µg/mL) in inhibited and denatured forms of ConA. The data show that native ConA affected: the survival, in the order of 30.6 %, and the locomotor performance of the flies; reduced cell viability to levels below 50 % (4.4 and 17.5 µg/mL); reduced nitric oxide levels; caused lipid peroxidation and increased protein and non-protein thiol content. In the Comet assay, native ConA (17.5 e 70 µg/mL) caused DNA damage higher than 50 %. In contrast, treatments with inhibited and denatured ConA did not affect oxidative stress markers and did not cause DNA damage. We believe that protein-carbohydrate interactions between ConA and carbohydrates of the plasma membrane are probably the major events involved in these activities, suggesting that native ConA activates mechanisms that induce oxidative stress and consequently DNA damage.

Entomotoxicity of jaburetox: revisiting the neurotoxic mechanisms in insects.

Ureases are metalloenzymes that hydrolyze urea to ammonia and carbamate. The main urease isoforms present in the seeds of Canavalia ensiformis (jack bean urease - JBU and canatoxin) exert a variety of biological activities. The insecticidal activity of JBU is mediated, at least in part, by jaburetox (Jbtx), a recombinant peptide derived from the JBU amino acid sequence. In this article, we review the neurotoxicity of Jbtx in insects. The insecticidal activity of Jbtx has been investigated in a variety of insect orders and species, including Blattodea (the cockroaches Blatella germânica, Nauphoeta cinerea, Periplaneta americana e Phoetalia pallida), Bruchidae (Callosobruchus maculatus - cowpea weevil), Diptera (Aedes aegypti - mosquito), Hemiptera (Dysdercus peruvianus - cotton stainer bug; Oncopeltus fasciatus - large milkweed bug, and the kissing bugs Rhodnius prolixus and Triatoma infestans), Lepidoptera (Spodoptera frugiperda - fall army worm) and Orthoptera (Locusta migratoria - locust). In N. cinerea, the injection of Jbtx induces marked alteration of locomotor and grooming behavior, whereas in T. infestans Jbtx causes leg paralysis, an extension of the proboscis and abnormal antennal movements. Electromyographical analysis showed that Jbtx causes complete neuromuscular blockade in P. pallida. The same treatment in N. cinerea and L. migratoria causes a decrease in the action potential firing rate. Jbtx forms membrane pore-channels compatible with cations in bilipid membranes. A study using B. germanica voltage-gated sodium (Nav1.1) channels that were heterologously expressed in Xenopus laevis oocytes correlated the entomotoxicity of Jbtx with the activation of these channels. Taken together, these findings demonstrate the potential of this peptide as a natural pesticide.

Schiff bases and their metal complexes as urease inhibitors - A brief review.

Schiff bases, an aldehyde- or ketone-like compounds in which the carbonyl group is replaced by an imine or azomethine, are some of the most widely used organic compounds. Indeed, they are widely used for industrial purposes and also exhibit a broad range of biological activities, including anti-urease activity. Ureases, enzymes that catalyze urea hydrolysis, have received considerable attention for their impact on living organisms' health, since the persistence of urease activity in human and animal cells can be the cause of some diseases and pathogen infections. This short review compiles examples of the most antiurease Schiff bases (0.23 µM < IC50 < 37.00 µM) and their metal complexes (0.03 µM < IC50 < 100 µM). Emphasis is given to ureases of Helicobacter pylori and Canavalia ensiformis, although the active site of this class of hydrolases is conserved among living organisms.

Dark Septate Endophytic Fungi Increase Green Manure-15N Recovery Efficiency, N Contents, and Micronutrients in Rice Grains.

An understanding of the interaction between rice and dark septate endophytic (DSE) fungi, under green fertilization, may lead to sustainable agricultural practices. Nevertheless, this interaction is still poorly understood. Therefore, in this study, we aimed to evaluate the accumulation of macro- and micronutrients, dry matter, and protein and N recovery efficiency from Canavalia ensiformis (L.)-15N in rice inoculated with DSE fungi. An experiment under greenhouse conditions was conducted in a randomized complete block design comprising split-plots, with five replicates of rice plants potted in non-sterilized soil. Rice (Piauí variety) seedlings were inoculated with DSE fungi, A101 and A103, or left uninoculated (control) and transplanted into pots containing 12 kg of soil, which had previously been supplemented with dry, finely ground shoot biomass of C. ensiformis enriched with 2.15 atom % 15N. Two collections were performed in the experiment: one at 54 days after transplanting (DAT) and one at 130 DAT (at maturation). Growth indicators (at 54 DAT), grain yield, nutrient content, recovery efficiency, and the amount of N derived from C. ensiformis were quantified. At 54 DAT, the N content, chlorophyll content, and plant height of inoculated plants had increased significantly compared with the control, and these plants were more proficient in the use of N derived from C. ensiformis. At maturation, plants inoculated with A103 were distinguished by the recovery efficiency and amount of N derived from C. ensiformis and N content in the grain and shoot being equal to that in A101 inoculation and higher than that in the control, resulting in a higher accumulation of crude protein and dry matter in the full grain and panicle of DSE-rice interaction. In addition, Fe and Ni contents in the grains of rice inoculated with these fungi doubled with respect to the control, and in A103 inoculation, we observed Mn accumulation that was three times higher than in the other treatments. Our results suggest that the inoculation of rice with DSE fungi represents a strategy to improve green manure-N recovery, grain yield per plant, and grain quality in terms of micronutrients contents in cropping systems with a low N input.

Dark Septate Endophytic Fungi Help Tomato to Acquire Nutrients from Ground Plant Material.

Dark septate endophytic (DSE) fungi are facultative biotrophs that associate with hundreds of plant species, contributing to their growth. These fungi may therefore aid in the search for sustainable agricultural practices. However, several ecological functions of DSE fungi need further clarification. The present study investigated the effects of DSE fungi inoculation on nutrient recovery efficiency, nutrient accumulation, and growth of tomato plants fertilized with organic and inorganic N sources. Two experiments were carried out under greenhouse conditions in a randomized blocks design, with five replicates of tomato seedlings grown in pots filled with non-sterile sandy soil. Tomato seedlings (cv. Santa Clara I-5300) inoculated with DSE fungi (isolates A101, A104, and A105) and without DSE fungi (control) were transplanted to pots filled with 12 kg of soil which had previously received finely ground plant material [Canavalia ensiformis (L.)] that was shoot enriched with 0.7 atom % 15N (organic N source experiment) or ammonium sulfate-15N enriched with 1 atom % 15N (mineral N source experiment). Growth indicators, nutrient content, amount of nitrogen (N) in the plant derived from ammonium sulfate-15N or C. ensiformis-15N, and recovery efficiency of 15N, P, and K by plants were quantified 50 days after transplanting. The treatment inoculated with DSE fungi and supplied with an organic N source showed significantly higher recovery efficiency of 15N, P, and K. In addition, the 15N, N, P, K, Ca, Mg, Fe, Mn, and Zn content, plant height, leaf number, leaf area (only for the A104 inoculation), and shoot dry matter increased. In contrast, the only positive effects observed in the presence of an inorganic N source were fertilizer-K recovery efficiency, content of K, and leaf area when inoculated with the fungus A104. Inoculation with A101, A104, and A105 promoted the growth of tomato using organic N source (finely ground C. ensiformis-15N plant material).

Development, productivity and quality of the fruits of the vine in consortium with cover crops / Desenvolvimento, produtividade e qualidade dos frutos da videira em consórcio com culturas de cobertura

The use of permanent or partial vegetative cover of the soil in the vineyards can influence the production and the quality of the grape. Thus, the objective of this work was to evaluate the development of the grapevine productivity as well as the qualitative characteristics of 'Isabel' grape, in consortium with soil cover plants. The experiment was conducted in the municipality of Itapuranga, GO, and consisted of six treatments established in a randomized block design, in a 3 x 2 factorial scheme, in five replications. The first factor consisted of a plant species cover the soil: Jack Beans (Canavalia ensiformis L. DC), lab-lab (Dolichos lab lab L.) and spontaneous plants. In the second factor, there were two pruning seasons of the grapevine crop, based on the sowing of the cover crops. In other words, the first pruning season in the vine was performed 25 days after sowing (DAS) of the cover plants and the second pruning season in the vine was performed at 55 DAS. In three crop cycles, the soil cover plants consortium with the grapevine does not influence the morphological variables, the productivity, the variables associated with the productivity and the qualitative characteristics of the grape. Different times of pruning influence the productivity and the associated variables in the grape crop. The pruning at 25 days after sowing of the cover plants presented better results for the morphological variables and qualitative characteristics of the grape. Therefore, for the local conditions and for the evaluated time, use of hedge plants did not influence the production of the vines as well as the quality of the grape. However pruning times can affect the development of the vine, reflecting its productivity and quality.(AU)

A utilização de cobertura vegetal permanente ou parcial do solo nos vinhedos pode influenciar a produção e a qualidade da uva. Assim, o objetivo desse trabalho foi avaliar o desenvolvimento da videira a produtividade, bem como as características qualitativas da uva 'Isabel', em consórcio com plantas de cobertura do solo. O experimento foi conduzido no município de Itapuranga, GO, e consistiu em seis tratamentos estabelecidos em delineamento de blocos ao acaso, no esquema fatorial 3 x 2, em cinco repetições. O primeiro fator consistiu em espécies de plantas cobertura do solo: feijão-de-porco (Canavalia ensiformis L. DC), lab-lab (Dolichos lab lab L.) e plantas espontâneas. No segundo fator, foram duas épocas de poda na cultura da videira, realizadas com base na semeadura das plantas de cobertura. Ou seja, a primeira época de poda na videira foi realizada 25 dias após a semeadura (DAS) das plantas de cobertura e a segunda época de poda na videira foi realizada aos 55 DAS. Em três ciclos de cultivo, as plantas de cobertura do solo consorciadas com a videira, não influenciam as variáveis morfológicas, a produtividade, as variáveis associadas a produtividade e as características qualitativas da uva. Diferentes épocas de poda influenciam a produtividade e as variáveis associadas na cultura da videira. A poda aos 25 dias após a semeadura, das plantas de cobertura, apresenta melhores resultados para as variáveis morfológicas e características qualitativas da uva. Portanto para as condições locais e pelo tempo avaliado, o uso de plantas de cobertura não influenciaram a produção das videiras bem como a qualidade da uva. Entretanto as épocas de poda podem afetar o desenvolvimento da videira, refletindo em sua produtividade e qualidade.(AU)

Development, productivity and quality of the fruits of the vine in consortium with cover crops / Desenvolvimento, produtividade e qualidade dos frutos da videira em consórcio com culturas de cobertura

The use of permanent or partial vegetative cover of the soil in the vineyards can influence the production and the quality of the grape. Thus, the objective of this work was to evaluate the development of the grapevine productivity as well as the qualitative characteristics of 'Isabel' grape, in consortium with soil cover plants. The experiment was conducted in the municipality of Itapuranga, GO, and consisted of six treatments established in a randomized block design, in a 3 x 2 factorial scheme, in five replications. The first factor consisted of a plant species cover the soil: Jack Beans (Canavalia ensiformis L. DC), lab-lab (Dolichos lab lab L.) and spontaneous plants. In the second factor, there were two pruning seasons of the grapevine crop, based on the sowing of the cover crops. In other words, the first pruning season in the vine was performed 25 days after sowing (DAS) of the cover plants and the second pruning season in the vine was performed at 55 DAS. In three crop cycles, the soil cover plants consortium with the grapevine does not influence the morphological variables, the productivity, the variables associated with the productivity and the qualitative characteristics of the grape. Different times of pruning influence the productivity and the associated variables in the grape crop. The pruning at 25 days after sowing of the cover plants presented better results for the morphological variables and qualitative characteristics of the grape. Therefore, for the local conditions and for the evaluated time, use of hedge plants did not influence the production of the vines as well as the quality of the grape. However pruning times can affect the development of the vine, reflecting its productivity and quality.

A utilização de cobertura vegetal permanente ou parcial do solo nos vinhedos pode influenciar a produção e a qualidade da uva. Assim, o objetivo desse trabalho foi avaliar o desenvolvimento da videira a produtividade, bem como as características qualitativas da uva 'Isabel', em consórcio com plantas de cobertura do solo. O experimento foi conduzido no município de Itapuranga, GO, e consistiu em seis tratamentos estabelecidos em delineamento de blocos ao acaso, no esquema fatorial 3 x 2, em cinco repetições. O primeiro fator consistiu em espécies de plantas cobertura do solo: feijão-de-porco (Canavalia ensiformis L. DC), lab-lab (Dolichos lab lab L.) e plantas espontâneas. No segundo fator, foram duas épocas de poda na cultura da videira, realizadas com base na semeadura das plantas de cobertura. Ou seja, a primeira época de poda na videira foi realizada 25 dias após a semeadura (DAS) das plantas de cobertura e a segunda época de poda na videira foi realizada aos 55 DAS. Em três ciclos de cultivo, as plantas de cobertura do solo consorciadas com a videira, não influenciam as variáveis morfológicas, a produtividade, as variáveis associadas a produtividade e as características qualitativas da uva. Diferentes épocas de poda influenciam a produtividade e as variáveis associadas na cultura da videira. A poda aos 25 dias após a semeadura, das plantas de cobertura, apresenta melhores resultados para as variáveis morfológicas e características qualitativas da uva. Portanto para as condições locais e pelo tempo avaliado, o uso de plantas de cobertura não influenciaram a produção das videiras bem como a qualidade da uva. Entretanto as épocas de poda podem afetar o desenvolvimento da videira, refletindo em sua produtividade e qualidade.

Number of leaves needed to model leaf area in jack bean plants using leaf dimensions / Número de folhas para modelar a área foliar de feijão de porco por dimensões foliares

Leaf area estimation models based on linear leaf dimensions are an important method because their application is not destructive to the leaves. For these models to be reliable, it is important that the estimation of model parameters is accurate, and for that to occur, the models must be generated using an adequate sample size (number of leaves). The objective of this study was to determine the number of leaves necessary to accurately model the leaf area of jack beans (Y), determined by digital photos, according to the width of the central leaflet (x), by a power model (Y = axb) generated through an iterative process. Accordingly, an experiment was performed in a 256 m2 area. A total of 745 leaves were randomly collected at six different crop development stages (29, 43, 57, 73, 87 and 101 days after emergence). Each leaf was comprised of a left, central and right leaflet. The width of the central leaflet (x) was measured on the 745 leaves. Leaf area (sum of the area of the left, central and right leaflets; Y) was then determined using a digital photo method. The number of leaves necessary for the estimation of the parameters a and b and the coefficient of determination (R2) of the power model were determined through resampling with replacement. The power model (Y = 4.2049x1.8215, R2 = 0.9701), based on the width of the central leaflet was determined to be adequate for estimating jack bean leaf area. Data collected from a sample of 200 leaves were determined to be sufficient for constructing an accurate power model for the leaf area of jack beans (Y) as a function of the width of the central leaflet (x), based on determinations of leaf area using digital photos.

Modelos de estimação de área foliar de plantas em função das dimensões lineares das folhas são importantes, principalmente, por não haver necessidade de destruição das folhas. Para modelos fidedignos, é importante que as estimativas de seus parâmetros sejam precisas, e, para isso, devem ser gerados a partir de um número adequado de folhas. O objetivo deste trabalho foi determinar o número de folhas necessário para modelar a área foliar de feijão de porco determinada por fotos digitais (Y) em função da largura do limbo do folíolo central da folha (x), por meio do modelo potência (Y = axb) gerado por processo iterativo. Para isso foi conduzido um experimento numa área de 256 m2, no qual, em seis períodos de desenvolvimento da cultura (29, 43, 57, 73, 87 e 101 dias após a emergência) foram coletadas, aleatoriamente, o total de 745 folhas. Cada folha é composta pelos folíolos esquerdo, central e direito. Nas 745 folhas foi mensurada a largura do limbo do folíolo central (x). A seguir, determinou-se a área foliar (soma da área dos folíolos esquerdo, central e direito) por meio do método de fotos digitais (Y). O número de folhas, necessário para a estimação dos parâmetros a e b do modelo potência e do coeficiente de determinação do modelo (R2), foi determinado por reamostragens, com reposição. Em feijão de porco, o modelo potência (Y = 4,2049x1,8215, R2 = 0,9701) da largura do limbo do folíolo central é adequado para estimar a área foliar obtida por fotos digitais. Mensurar 200 folhas é suficiente para construir modelos precisos do tipo potência, da área foliar de feijão de porco determinada por fotos digitais (Y) em função da largura do limbo do folíolo central da folha (x).

An overview on the potential of natural products as ureases inhibitors: A review.

Ureases, enzymes that catalyze urea hydrolysis, have received considerable attention for their impact on living organisms' health and life quality. On the one hand, the persistence of urease activity in human and animal cells can be the cause of some diseases and pathogen infections. On the other hand, food production can be negatively affected by ureases of soil microbiota that, in turn, lead to losses of nitrogenous nutrients in fields supplemented with urea as fertilizer. In this context, nature has proven to be a rich resource of natural products bearing a variety of scaffolds that decrease the ureolytic activity of ureases from different organisms. Therefore, this work compiles the state-of-the-art researches focused on the potential of plant natural products (present in extracts or as pure compounds) as urease inhibitors of clinical and/or agricultural interests. Emphasis is given to ureases of Helicobacter pylori, Canavalia ensiformis and soil microbiota although the active site of this class of hydrolases is conserved among living organisms.

Pliable natural biocide: Jaburetox is an intrinsically disordered insecticidal and fungicidal polypeptide derived from jack bean urease.

Jaburetox is a polypeptide derived from jack bean (Canavalia ensiformis) urease and toxic to a broad spectrum of insects, phytopathogenic filamentous fungi and yeasts of medical importance. The elucidation of the structural basis for the mode of action of Jaburetox is the focus of this multifaceted study. Jaburetox in solution is a monomer of 11.0 kDa featuring a large hydrodynamic radius, suggestive of a disordered polypeptide. The intrinsically disordered nature of Jaburetox was theoretically predicted by a comprehensive bioinformatics analysis and experimentally confirmed by light scattering as well as by circular dichroism and NMR spectroscopy. NMR signal assignment provided backbone secondary chemical shifts that indicated that Jaburetox has a low propensity to assume a stable secondary structure. (15)N relaxation studies revealed significant backbone mobility, especially in the N-terminal portion of the polypeptide. The solution structure of Jaburetox shows the presence of an α-helical motif close to the N terminus, together with two turn-like structures situated in the central portion of the protein and close to the C terminus. Similar regions were predicted as potential protein-protein interaction sites using computational tools. The knowledge of the structural properties of Jaburetox in solution is a key step to correlate its structural and biological activities.

Cadmium accumulation by jack-bean and sorghum in hydroponic culture.

Among the technologies used to recuperate cadmium (Cd) contaminated soils, phytoextraction are particularly important, where the selection of suitable plants is critical to the success of the soil remediation. Thus, the objectives of this study were to evaluate the responses of jack-bean and sorghum to Cd supply and to quantify Cd accumulation by these species grown in hydroponic culture. The plants were subjected to 0, 15, 30, or 60 µmol Cd L(-1) in the nutrient solution, and gas exchange, plant growth and Cd accumulation were measured at 25 days after starting Cd treatments. The Cd supply severely reduced growth of shoots and roots in both species. In jack-bean, Cd decreased photosynthesis by 56-86%, stomatal conductance by 59-85% and transpiration by 48-80%. The concentrations and amounts of Cd accumulated in the plant tissues were proportional to the metal supply in the nutrient solution. Sorghum was more tolerant than jack-bean to Cd toxicity, but the latter showed a greater metal concentration and accumulation in the shoot. Therefore, jack-bean would be more suitable than sorghum for use in Cd phytoremediation programs based on phytoextraction.

Tamanho de parcela e número de repetições em feijão de porco / Plot size and number of replicates in jack bean

Os objetivos deste trabalho foram determinar o tamanho ótimo de parcela e o número de repetições para avaliar caracteres de feijão de porco (Canavalia ensiformis). Foram realizados seis ensaios de uniformidade de 5m×5m (25m2). Cada ensaio foi dividido em 25 unidades experimentais básicas (UEB) de 1m×1m, totalizando 150UEB. Foi pesada a massa verde de vagens (MVV) e a massa verde de parte aérea sem vagens (MVPASV) e calculada a massa verde de parte aérea (MVPA=MVV+MVPASV) das plantas de cada UEB. Foi determinado o tamanho ótimo de parcela e comparadas as médias entre os caracteres MVV, MVPASV e MVPA. Após, foi calculado o número de repetições. Os tamanhos ótimos de parcela para avaliar a massa verde de vagens, a massa verde de parte aérea sem vagens e a massa verde de parte aérea são, respectivamente, 8,59m2, 6,14m2 e 5,85m2. Quatro repetições, para avaliar até 50 tratamentos, no delineamento blocos ao acaso, são suficientes para identificar, como significativas a 5% de probabilidade, pelo teste de Tukey, diferenças entre médias de tratamentos de 55,48%, 39,66% e 37,78% das médias de massa verde de vagens, de massa verde de parte aérea sem vagens e de massa verde de parte aérea do experimento, respectivamente.(AU)

The objectives of this research were to determine the optimum plot size and the number of repetitions to evaluate characters of jack bean (Canavalia ensiformis). It was carried six uniformity assays of size 5m×5m (25m2). Each assay was divided in 25 basic experimental units (UEB) of 1m×1m, totaling 150UEB. The fresh mass of pods (MVV) and fresh mass of aerial part without pods (MVPASV) were weighed and fresh mass of the aerial part (MVPA=MVV+MVPASV) of plants of each UEB was calculated. The optimum plot size was determined and the means were compared, between characters MVV, MVPASV and MVPA. The number of replicates was determined. The optimum plot sizes to evaluate the fresh mass of pods, fresh mass of aerial part without pods and fresh mass of aerial part are, respectively, 8.59m2, 6.14m2 and 5.85m2. Four replications, to evaluate up to 50 treatments, in randomized block designs, are sufficient to identify, as significant at the 5% probability by Tukey test, differences between treatment means 55.48%, 39.66% and 37.78% of the average fresh mass of pods, fresh mass of aerial part without pods and fresh mass of aerial part of the experiment, respectively.(AU)

Tamanho de parcela e número de repetições em feijão de porco / Plot size and number of replicates in jack bean

Os objetivos deste trabalho foram determinar o tamanho ótimo de parcela e o número de repetições para avaliar caracteres de feijão de porco (Canavalia ensiformis). Foram realizados seis ensaios de uniformidade de 5m×5m (25m2). Cada ensaio foi dividido em 25 unidades experimentais básicas (UEB) de 1m×1m, totalizando 150UEB. Foi pesada a massa verde de vagens (MVV) e a massa verde de parte aérea sem vagens (MVPASV) e calculada a massa verde de parte aérea (MVPA=MVV+MVPASV) das plantas de cada UEB. Foi determinado o tamanho ótimo de parcela e comparadas as médias entre os caracteres MVV, MVPASV e MVPA. Após, foi calculado o número de repetições. Os tamanhos ótimos de parcela para avaliar a massa verde de vagens, a massa verde de parte aérea sem vagens e a massa verde de parte aérea são, respectivamente, 8,59m2, 6,14m2 e 5,85m2. Quatro repetições, para avaliar até 50 tratamentos, no delineamento blocos ao acaso, são suficientes para identificar, como significativas a 5% de probabilidade, pelo teste de Tukey, diferenças entre médias de tratamentos de 55,48%, 39,66% e 37,78% das médias de massa verde de vagens, de massa verde de parte aérea sem vagens e de massa verde de parte aérea do experimento, respectivamente.

The objectives of this research were to determine the optimum plot size and the number of repetitions to evaluate characters of jack bean (Canavalia ensiformis). It was carried six uniformity assays of size 5m×5m (25m2). Each assay was divided in 25 basic experimental units (UEB) of 1m×1m, totaling 150UEB. The fresh mass of pods (MVV) and fresh mass of aerial part without pods (MVPASV) were weighed and fresh mass of the aerial part (MVPA=MVV+MVPASV) of plants of each UEB was calculated. The optimum plot size was determined and the means were compared, between characters MVV, MVPASV and MVPA. The number of replicates was determined. The optimum plot sizes to evaluate the fresh mass of pods, fresh mass of aerial part without pods and fresh mass of aerial part are, respectively, 8.59m2, 6.14m2 and 5.85m2. Four replications, to evaluate up to 50 treatments, in randomized block designs, are sufficient to identify, as significant at the 5% probability by Tukey test, differences between treatment means 55.48%, 39.66% and 37.78% of the average fresh mass of pods, fresh mass of aerial part without pods and fresh mass of aerial part of the experiment, respectively.

Canavalia ensiformis urease, Jaburetox and derived peptides form ion channels in planar lipid bilayers.

Ureases catalyze the hydrolysis of urea into NH3 and CO2. They are synthesized by plants, fungi and bacteria but not by animals. Ureases display biological activities unrelated to their enzymatic activity, i.e., platelet and neutrophil activation, fungus inhibition and insecticidal effect. Urease from Canavalia ensiformis (jack bean) is toxic to several hemipteran and coleopteran insects. Jaburetox is an insecticidal fragment derived from jack bean urease. Among other effects, Jaburetox has been shown to interact with lipid vesicles. In this work, the ion channel activity of C. ensiformis urease, Jaburetox and three deletion mutants of Jaburetox (one lacking the N-terminal region, one lacking the C-terminal region and one missing the central ß-hairpin) were tested on planar lipid bilayers. All proteins formed well resolved, highly cation-selective channels exhibiting two conducting states whose conductance ranges were 7-18pS and 32-79pS, respectively. Urease and the N-terminal mutant of Jaburetox were more active at negative potentials, while the channels of the other peptides did not display voltage-dependence. This is the first direct demonstration of the capacity of C. ensiformis urease and Jaburetox to permeabilize membranes through an ion channel-based mechanism, which may be a crucial step of their diverse biological activities, including host defense.

Role of lysine and acidic amino acid residues on the insecticidal activity of Jackbean urease.

Canavalia ensiformis has three isoforms of urease: Jackbean urease (JBU), Jackbean urease II and canatoxin. These isoforms present several biological activities, independent from the enzymatic property, such as entomotoxicity and antifungal properties. The entomotoxic activity is a property of the whole protein, as well as of a 10 kDa peptide released by insect digestive enzymes. Here we have used chemical modification to observe the influence of lysines and acidic residues on JBU enzymatic and insecticidal activities. Chemical modification of lysine residues was performed with dimethylamine-borane complex and formaldehyde, and acidic residues were modified by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and ethylenediamine. Derivatized ureases, called JBU-Lys (lysine-modified) and JBU-Ac (acidic residues-modified), were assayed for their biochemical and insecticidal properties. Neither modification altered significantly the kinetic parameters analyzed, indicating that no residue critical for the enzyme activity was affected and that the modifications did not incur in any significant structural alteration. On the other hand, both modifications reduced the toxic activity of the native protein fed to Dysdercus peruvianus. The changes observed in the entomotoxic property of the derivatized proteins reflect alterations in different steps of JBU's toxicity towards insects. JBU-Ac is not susceptible to hydrolysis by insect digestive enzymes, hence impairing the release of toxic peptide(s), while JBU-Lys is processed as the native protein. On the other hand, the antidiuretic effect of JBU on Rhodnius prolixus is altered in JBU-Lys, but not in JBU-Ac. Altogether, these data emphasize the role of lysine and acidic residues on the insecticidal properties of ureases.

Nitrogen contributions of legume roots to cabbage nutrition

The effects of roots are generally not considered in studies assessing crop responses to green manure. However, measuring such effects can contribute to a better understanding of crop rotation. In two experiments, we evaluated the content of legume-N in crop tissue and the fertilizer value of the roots and shoots of two legume species. Roots, shoots, or whole plants of the legumes sunhemp (Crotalaria juncea) and jack beans (Canavalia ensiformis) were cropped as green manure to supply nitrogen to cabbage crops (Brassica oleracea var. capitata). The principle of the A-value technique was applied to estimate the fertilizer value of each plant part. In a pot experiment, both the content of legume-N in cabbage and the fertilizer value of the whole plant was higher than the shoots, which was in turn higher than that of the roots. In field condition, roots had a decreasing effect on the N content of cabbage plants. Growing cabbage on legume root residue resulted in an increased absorption of 15N-urea, resulting in negative values for legume-N content: -13.59 g kg-1 and -3.51 g kg-1 for sunhemp and jack beans, respectively. Suggesting both low N supply by roots and N immobilization in soil organic matter or microbial biomass. Future research should focus on estimating the net N acquisition by plants from root residues under field conditions, where rooting patterns and biomass distribution differ from those in pot experiments, therefore giving a more realistic quantitative estimate.

Nitrogen contributions of legume roots to cabbage nutrition

The effects of roots are generally not considered in studies assessing crop responses to green manure. However, measuring such effects can contribute to a better understanding of crop rotation. In two experiments, we evaluated the content of legume-N in crop tissue and the fertilizer value of the roots and shoots of two legume species. Roots, shoots, or whole plants of the legumes sunhemp (Crotalaria juncea) and jack beans (Canavalia ensiformis) were cropped as green manure to supply nitrogen to cabbage crops (Brassica oleracea var. capitata). The principle of the A-value technique was applied to estimate the fertilizer value of each plant part. In a pot experiment, both the content of legume-N in cabbage and the fertilizer value of the whole plant was higher than the shoots, which was in turn higher than that of the roots. In field condition, roots had a decreasing effect on the N content of cabbage plants. Growing cabbage on legume root residue resulted in an increased absorption of 15N-urea, resulting in negative values for legume-N content: -13.59 g kg-1 and -3.51 g kg-1 for sunhemp and jack beans, respectively. Suggesting both low N supply by roots and N immobilization in soil organic matter or microbial biomass. Future research should focus on estimating the net N acquisition by plants from root residues under field conditions, where rooting patterns and biomass distribution differ from those in pot experiments, therefore giving a more realistic quantitative estimate.