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Vibrational spectroscopy analysis of full-ripened fig fruits (Ficus carica L.) was acquired using Fourier-transformed infrared (FTIR) spectroscopy by attenuated total reflectance (ATR). The objective of this study was to investigate accurate discrimination of 25 fig cultivars using chemometric analysis of both ATR–FTIR fingerprinting and in-vitro antioxidant activity along with chromatic coordinates color. In-vitro antioxidant activity was assessed through three methods and displayed statistically significant differences across cultivars and between the fruit parts, with promising antioxidant potency. Infrared spectra were measured separately on both peels and pulp to better know which fruit part provides high discrimination throughput between cultivars. The results showed vibration intensities of five fingerprint regions displaying statically significant differences. The highest vibration intensity occurred in the region of 1175–940 cm−1 including the phenols fingerprint. Principal components analysis based on integrated intensities corresponding to fingerprint regions, revealed two main groups in pulp samples, while five groups in peels samples. The pulp extracts of ‘Nabout’ showed a typical vibration in 3000–2800 cm−1 and 1775–1725 cm−1 regions and, therefore was classified as single subset in cultivars scatterplot. This cultivar had a light-colored fig and exhibited the highest antioxidant potency for all essays particularly in peel extracts. The biochemical assessment and FTIR fingerprinting data were involved in PCA analysis, and that displayed some dissimilarities in the classification patterns, given the fact that antioxidant activities and chromaticity together could not totally explain the classification based on FTIR fingerprinting between peel and pulp. Application of FTIR–ATR spectroscopy to discriminate fig cultivars seems to be a rapid, accurate and cost-effective alternative to laborious measurement techniques, in fig quality screening and preselection, such as chromatography analysis. This study suggests the use of fig peels for a high-level discrimination while using ATR–FTIR spectroscopy, since it provides high-throughput screening framework.

Plant cell walls (CW) are composed mainly of cellulose–hemicellulose networks embedded in a pectin matrix. CW apposition, including papilla formation, is often associated with plant defence...

Antimicrobial preservatives are widely added to health products to prevent microbial contamination. However, because of the risks attributed to several synthetic agents, manufacturers are searching for new natural agents. Therefore, this work investigated the different physicochemical characteristics of one of those natural ingredients, the essential oil (EO) of Moroccan thyme (Thymus satureioides C.) and its antimicrobial potential against five microbial strains. The physicochemical parameters (density, refractive index, optical rotation, miscibility, acid value, ester value, and flash point) were measured and the chemical composition was determined by GC/MS. The antimicrobial activity was assessed using disc diffusion method and a macrodilution broth method. The EO yield was 1.01% compared to the dry matter. Fifty-two compounds were identified. The major compounds were thymol (28.66%), borneol (21.16%) and α- terpineol (12.33%). The disc diffusion method revealed that all the strains tested showed sensitivity to the EO at concentration of 1636 μg per disc. For the minimum inhibitory concentration (MIC) and the minimum microbicidal concentrations (MMC), similar results were obtained for Staphylococcus aureus and Escherichia coli (640 μg/mL), for Pseudomonas aeruginosa (960 μg/mL) and for Candida albicans (800 μg/mL) baring Aspergillus brasiliensis, which had 480 μg/mL and 640 μg/mL for the MIC and MMC, respectively.

The main objective of this study was to evaluate the ability of both antagonistic bacteria Bacillus amyloliquefaciens (SF14) and Alcaligenes faecalis (ACBC1) used in combination with salicylic acid (SA) to effectively control brown rot disease caused by Monilinia fructigena. Four concentrations of salicylic acid (0.5%, 2%, 3.5%, and 5%) were tested under in vitro and in vivo conditions. Furthermore, the impact of biological treatments on nectarine fruit parameters&rsquo, quality, in particular, weight loss, titratable acidity, and soluble solids content, was evaluated. Regardless of the bacterium, the results indicated that all combined treatments displayed a strong inhibitory effect on the mycelial growth of M. fructigena and disease severity. Interestingly, all SA concentrations significantly improved the biocontrol activity of each antagonist. The mycelial growth inhibition rate ranged from 9.79% to 88.02% with the highest reduction rate recorded for bacterial antagonists in combination with SA at both concentrations of 0.5% and 3.5%. The in vivo results confirmed the in vitro results with a disease severity varying from 0.00% to 51.91%. A significant biocontrol improvement was obtained with both antagonistic bacteria when used in combination with SA at concentrations of 0.5% and 2%. The lowest disease severity observed with ACBC1 compared with SF14 is likely due to a rapid adaptation and increase of antagonistic bacteria population in wounded sites. The impact of all biological treatments revealed moderate significant changes in the fruit quality parameters with weight loss for several treatments. These results suggest that the improved disease control of both antagonistic bacteria was more likely directly linked to both the inhibitory effects of SA on pathogen growth and induced fruit resistance.

Rhizomania is one of the most devastating diseases of sugar beet worldwide. The disease poses a serious threat to Moroccan production and it is capable of significantly decreasing quality and yield of sugar beet plantations. The long-term survival of its fungal vector ( Polymyxa betae ) in soil makes it a very difficult disease to manage. Therefore, this study investigated the potential of a non-pathogenic fungal Fusarium oxysporum strain Fo47 to control Polymyxa betae . This biocontrol agent was applied as soil treatment, seed treatment, or a combination of the both treatments. A bio-test was performed on treated soil. After four weeks of culture, the roots of sugar beet seedlings were retrieved and analyzed by the DAS-ELISA test. Results indicated that F. oxysporium Fo47 reduced the activity and survival of P. betae when compared to a reference biocontrol agent Trichoderma harzianum , which only revealed significant in reducing the viral load of Beet Necrotic Yellow Vein Virus (BNYVV) as seed treatment. The non-pathogenic Fusarium oxysporum Fo47 was more effective as soil treatment and allowed almost the same reduction of BNYVV virus concentration as T. harzianum 908. Therefore, our findings emphasizes that the performance of the biocontrol agent depends on the method of application.

To develop eco-friendly alternative control strategies for medfly, mass trapping trials were conducted in the central Morocco during the crop season 2016. Two control methods, mass trapping and the attract-and-kill technique were compared for the control of medfly on two peach varieties (?Rome Star? and ?Ryan Sun?) in Sefou district. For mass trapping, 62 traps/1.23 ha of MagnetTMMed type baited with ammonium acetate, trimethylamine, putrescine and 0.01 g of deltamethrin were installed on both varieties. In plots testing the attract-and-kill technique, treatments with malathion in mixture with protein hydrolyzate were applied to straw tufts attached to branches of the same varieties whenever 1 fly was caught on a Trimedlure trap installed at the center of each plot. The results showed that the number of flies captured by mass trapping reached 508 and 489 adults on ?Rome Star? and ?Ryan Sun?, respectively. The average number varied from 1 to 3 adults/trap/day, depending on the date of capture and the variety, and females accounted for 62-100% of total caught flies. In plots protected by the attract-and-kill technique, and taking into account the threshold adopted by the farm, 11 and 15 treatments were carried out respectively on the ?Ryan Sun? and ?Rome Star? varieties. Overall, infestation rates in plots did not exceed 0.3% before or at harvest with mass trapping versus 0.9% with the attract-and-kill technique. On fruit dropped on the ground, the infestation rate did not exceed 4% in mass trapping, compared to 11.5% in the chemically treated plots. Mass trapping was therefore proved to be an effective and eco-friendly tool for managing medfly on peach fruit.

This study aimed at evaluating the antagonistic activity of 16 bacterial strains for the control of brown rot disease caused by Monilinia fructigena, and M. laxa under in vitro and a semi-commercial large-scale trial. These bacterial antagonists’ belonging to the genera Alcaligenes, Bacillus, Brevibacterium, Pantoea, Pseudomonas, and Serratia were previously proven effective for control of fire blight of apple. The in vitro dual culture bioassay showed the highest inhibition rates of mycelial growth ranging from 55 to 95% and from 43 to 94% for M. fructigena and M. laxa, respectively. The in vivo bioassay showed moderate and strong inhibition for M. fructigena and M. laxa, respectively. The inhibition rates were dependent on incubation time as well as pathogen virulence. The free-cell bacterial filtrate revealed substantial mycelial growth inhibition ranging from 66 to 86%. The inhibition of conidial germination was from 32 to 78%, suggesting the involvement of metabolites in their biocontrol activity. The antifungal effect of the volatile compounds (VCOs) was observed for all bacteria with mycelial inhibition varying from 12 to 70%. Overall, their efficacy was substantially affected by the nature of the bacterial strains and the modes of action. Taken together, these results underscore that ACBC1 and SF14 for M. fructigena and SP10 and ACBP1 for M. laxa were the most effective bacterial strains. These strains were confirmed effective in a semi-commercial large-scale trial. Interestingly, their efficacies were found to be comparable to those of both commercial BCAs (B. subtilis Y1336 and P. agglomerans P10c), but slightly lower than thiophanate-methyl fungicide. The ability of most bacterial strains to produce lytic enzymes (Amylase, Protease or Cellulase) and lipopeptides (bacillomycin, fengycin, iturin and surfactin) was demonstrated by biochemical and molecular analyzes. Therefore, our findings suggest that the bacterial antagonists ACBC1, SF14, SP10 and ACBP1, have the potential to prevent brown rot disease.

The effect of microwave treatment to reduce the cooking times of five pulses, namely red lentil, chickpea, pigeon pea, mung bean, and pinto bean, were determined in this study. Pulses from 10 to 18% moisture contents were treated using 400 to 600 W microwaves for 14 to 56 s. The cooking times of microwave-treated pulses were significantly lower than that of the control samples. The lowest cooking time was observed for 18% moisture content chickpea and pigeon pea treated with 600 W for 56 s. The Fourier transform mid-infrared spectra in both lipids and fingerprint regions showed the macronutrients differences among the five pulses. Major changes were observed in the amide I region of microwave treated pulses. This effect of microwave treatment was higher in red lentil, chickpea, and mung bean than in pigeon pea and pinto bean at 10% moisture content. At 18% moisture content, the change of β-sheets to aggregates was observed in all pulses due to microwave treatment.

Monilinia fructigena is one of the most important fungal pathogens causing brown rot on apple and is heavily affecting fruit production. The main objective of this study was to screen for potential bacterial isolates with higher antagonistic activity against M. fructigena. Our study focused on the identification of potential bacterial isolates capable of reducing both the mycelial growth of M. fructigena and the disease severity using in vitro and in planta trials, respectively. To achieve this goal, thirteen bacteria, isolated from natural soil, were evaluated for their abilities to produce lytic enzymes (amylase, cellulase and protease), hydrocyanic acid (HCN) and lipopeptides (bacillomycin, fengycin, iturin and surfactin). Further, results from the dual culture method, volatile and bacterial free-cell filtrate bioassays indicated that tested isolates showed a fungicidal activity against the mycelial growth of M. fructigena. Thus, out of the 13 isolates tested, 12 exhibited significant mycelial inhibition (more than 70%) against M. fructigena, while remaining the last isolate displayed only a partial inhibition (up to 43%). Further, 12 of the bacteria isolates displayed an amylase production, 10 showed cellulase production, 11 revealed protease production, while only 2 displayed HCN production. In addition, most bacterial isolates were found to have genes encoding for different lipopeptides: bacillomycin (10), fengycin (3), iturin (11) and surfactin (1). Interestingly, two bacterial isolates, Bacillus amyloliquefaciens B10W10 and Pseudomonas sp. B11W11 were found to be the most effective and displayed the lowest disease severity in planta trial. These two bacteria reduced the brown rot incidence compared to the synthetic fungicide in a semi-commercial large-scale trial. Therefore, our findings suggest that these two later bacterial isolates provide apple protection against M. fructigena via direct and indirect mechanisms. These isolates may be used, therefore, as potential biological control agents (BCAs) in preventive treatment to control brown rot disease on apple fruits.

Organic farming has been increasing steadily over the last decade and is expected to grow drastically in the future. Plant parasitic nematodes (PPNs) are known as one of the most important pests attacking various plants in conventional and organic farming systems. A survey was conducted in January 2019 to determine the occurrence and diversity of PPNs, their associations with soil properties, and to assess their management methods in organically farmed fields in Southern Morocco. Twelve genera of PPNs were identified in soil and root samples collected from 53 organic fields, including Meloidogyne, Pratylenchus, Helicotylenchus, Tylenchus, Tylenchorynchus, Criconemoides, Trichodorus, and Xiphinema. The root-knot nematodes (Meloidogyne spp.) and the root-lesion nematode (Pratylenchus spp.) were the most prevalent PPNs. Vegetable crops (bean, onion, and tomato) had high nematode diversity indices compared to some aromatic and medicinal crops, including the Shannon, Evenness, and plant parasitic index (PPI). Our study underlined that several PPN genera were significantly correlated with soil physico-chemical properties, in particular, soil structure and organic matter. Therefore, it was concluded that soil properties have a considerable impact on PPN communities in organic farming systems located in Southern Morocco. There are numerous strategies for the control of PPNs in organic farming systems.

Brown rot, caused by both fungal pathogens Monilinia laxa and M. fructigena, is considered as one of major pre-and postharvest pathogen of tree fruit. Therefore, this study aimed at evaluating the in vitro and in vivo ability of pomegranate peel aqueous extract (PGE) against both fungal pathogens causing brown rot. Results showed a significant antifungal activity on the in vitro mycelial growth of both fungi with inhibition rates ranging from 76.65 to 90%. In addition, obtained results highlighted a positive correlation between the concentration rates of PGE and the mycelial growth inhibition and the EC50 were 9.93 and 12.84 mg/ml for M. fructigena and M. laxa, respectively. Interestingly, spore germination of both pathogenic fungi was significantly reduced by PGE with EC50 of 7.7 and 8.58 mg/ml for M. fructigena and M. laxa. The germ tube elongation was significantly reduced by PGE. Furthermore, the in vivo trial on apple fruit showed promising results with disease severity of 21.03 and 42% respectively for M. laxa and M. fructigena at 50 mg/ml aqueous extract concentration. This concentration showed also the highest content of total phenolic (2737.44 mg GAE/L) and flavonoid (309 mg QE/L). It was concluded that the aqueous extract of pomegranate peels might be a sustainable alternative control strategy of brown rot. As a result, studies on mechanisms behind its effectiveness and practical use as formulated biofungicide product should be further considered in more details.

ATR-FTIR spectroscopy in combination with uni- and multivariate analysis was used to quantify the spectral–chemical composition of the leaf cuticle of pea, investigating the effects of variety and heat stress. Field pea (Pisum sativum L.) is sensitive to heat stress and our goal was to improve canopy cooling and flower retention by investigating the protective role of lipid-related compounds in leaf cuticle, and to use results in the future to identify heat resistant genotypes. The objective was to use Attenuated Total Reflection (ATR)-Fourier Transform Infrared (FTIR) spectroscopy, a non-invasive technique, to investigate and quantify changes in adaxial cuticles of fresh leaves of pea varieties that were subjected to heat stress. Eleven varieties were grown under control (24/18 °C day/night) and heat stress conditions (35/18 °C day/night, for 5 days at the early flowering stage). These 11 had significant spectral differences in the integrated area of the main lipid region, CH2 region, CH3 peak, asymmetric and symmetric CH2 peaks, ester carbonyl peak, and the peak area ratio of CH2 to CH3 and ester carbonyl to CH2 asymmetric peak, indicating that cuticles had spectral–chemical diversity of waxes, cutin, and polysaccharides. Results indicated considerable diversity in spectral–chemical makeup of leaf cuticles within commercially available field pea varieties and they responded differently to high growth temperature, revealing their diverse potential to resist heat stress. The ATR-FTIR spectral technique can, therefore, be further used as a medium-throughput approach for rapid screening of superior cultivars for heat tolerance.

In the present study, FTIR spectroscopy and hyperspectral imaging was introduced as a non-destructive, sensitive-reliable tool for assessing the tripartite kernel-fungal endophyte environment interaction. Composition of coleorhizae of Triticum durum was studied under ambient and drought stress conditions. The OH-stretch IR absorption spectrum suggests that the water-deficit was possibly improved or moderated by kernel’s endophytic partner. The OH-stretch frequency pattern coincides with other (growth and stress) related molecular changes. Analysis of lipid (3100–2800 cm−1) and protein (1700–1550 cm−1) regions seems to demonstrate that drought has a positive impact on lipids. The fungal endosymbiont direct contact with kernel during germination had highest effect on both lipid and protein (Amide I and II) groups, indicating an increased stress resistance in inoculated kernel. Compared to the indirect kernel-fungus interaction and to non-treated kernels (control), direct interaction produced highest effect on lipids. Among treatments, the fingerprint region (1800–800 cm−1) and SEM images indicated an important shift in glucose oligosaccharides, possibly linked to coleorhiza-polymer layer disappearance. Acquired differentiation in coleorhiza composition of T. durum, between ambient and drought conditions, suggests that FTIR spectroscopy could be a promising tool for studying endosymbiont-plant interactions within a changing environment.

Rhizomania is one of serious threat to sugar beet production in Morocco and in several parts of the world. This disease led to a statistically significant decrease in the quality and yield of sugar beet plantations. Therefore, this study aimed at comparing the efficacy of six commonly used RNA extraction methods for the detection, recovery of RNA of beet necrotic yellow vein virus (BNYVV) and removal of amplification inhibitors by reverse transcription-polymerase chain reaction (RT-PCR). The efficiency of these extraction methods was then compared to that of a commercial isolation kit with high content of phenolic compounds. The results showed that the extraction with the lithium chloride technique, the commercial kit, and direct and membrane spotting crude extract methods were found effective in yielding a higher purity and a higher concentration of RNA when compared to the other tested methods. Extraction with the lithium chloride technique and the Qiagen kit (RNeasy Plant Mini Kit) allowed the most intense band, whereas the CTAB method has generated the least intense band. Furthermore, the silica capture extraction method did not yield any RNA after extraction and electrophoresis. Consequently, it was concluded that, of these six methods, the lithium chloride technique and the Qiagen kit are the most appropriate for the extraction of viral RNA from sugar beet samples prior to RT-PCR for detecting BNYVV.

Modern infrared (IR) spectroscopy and imaging has a wide range of applications in health and plant sciences. Initially, it was extensively used for the study of proteins, nucleotides, lipids and carbohydrates. With time, its use has extended to disease assessment to discriminate healthy and diseased samples on the basis of chemical changes. The application of an advanced focal plane array detector, which is able to scan a large area of samples in a short time, helps in investigating specific changes that could be correlated with different environmental stresses. An IR microscope connected with a synchrotron light source further enhances the lateral spatial resolution at diffraction limit because of the compact beam size. For example, synchrotron-based IR spectroscopy imaging in combination with multivariate statistical analysis has been proven to be a powerful non-destructive analytical tool to probe changes in plant cell wall composition/structure in response to biological processes and environme...

Whereas long days (LDs) sustain shoot elongation, short days (SDs) induce growth cessation and formation of dormant buds in young individuals of a wide range of temperate and boreal tree species. In specific conifers, including Norway spruce, photoperiodic control of bud development is associated with the formation of a plate of thick-walled cells, denoted as the crown, at the base of the bud. Information about cellular characteristics of this crown region is limited. We aimed to test whether the crown region is an important SD-induced barrier ensuring dehydration of the developing winter bud by preventing water influx. Using microscopy and synchrotron techniques, we show here that under LD, cell walls in growing shoot tips had highly methyl-esterified homogalacturonan pectin. During SD-induced bud development, the homogalacturonan in the crown region was de-methyl-esterified, enabling Ca2+ binding and crosslinking, a process known to decrease cell wall water permeability by reducing pectin pore size. In addition, there was abundant callose deposition at plasmodesmata in the crown region, and xylem connections between the bud and the subtending shoot were blocked. Consistent with reduced water transport across the crown region into the bud, uptake of fluorescein in shoot tips was blocked at the base of the bud under SD. Upon transfer from SD to bud-break-inducing LD, these processes were reversed, and aquaporin transcript levels significantly increased in young stem tissue after 4 weeks under LD. These findings indicate that terminal bud development is associated with reduced water transport through decreased cell wall permeability and blocking of plasmodesmata and xylem connections in the crown structure. This provides further understanding of the regulatory mechanism for growth-dormancy cycling in coniferous tree species such as Norway spruce.

Clubroot disease is a serious threat to canola production in western Canada and many parts of the world. Rcr1 is a clubroot resistance (CR) gene identified recently and its molecular mechanisms in mediating CR have been studied using several omics approaches. The current study aimed to characterize the biochemical changes in the cell wall of canola roots connecting to key molecular mechanisms of this CR gene identified in prior studies using Fourier transform infrared (FTIR) spectroscopy. The expression of nine genes involved in phenylpropanoid metabolism was also studied using qPCR. Between susceptible (S) and resistance (R) samples, the most notable biochemical changes were related to an increased biosynthesis of lignin and phenolics. These results were supported by the transcription data on higher expression of BrPAL1. The up-regulation of PAL is indicative of an inducible defence response conferred by Rcr1; the activation of this basal defence gene via the phenylpropanoid pathway may contribute to clubroot resistance conferred by Rcr1. The data indicate that several cell-wall components, including lignin and pectin, may play a role in defence responses against clubroot. Principal components analysis of FTIR data separated non-inoculated samples from inoculated samples, but not so much between inoculated S and inoculated R samples. It is also shown that FTIR spectroscopy can be a useful tool in studying plant-pathogen interaction at cellular levels.

Pichia guilliermondii strain Z1, which was previously proven to be effective against blue mold of citrus fruit, has been further tested in controlled conditions to determine whether the yeast, as an alternative for synthetic fungicides, would be compatible with other postharvest practices used commercially. In particular, commercial fruit waxes can reduce their survival and effectiveness. The commercial fruit waxes tested, in combination at 20% with strain Z1, included microcrystalline, ester gum, candelilla, beeswax, montan, paraffin, rice bran, rosin maleic, carnauba, shellac, and one mixture shellac plus carnauba. Beeswax, paraffin, rosin maleic, carnauba, and shellac increased significantly strain Z1 survival in Petri dish assays. Candelilla, beeswax, rice bran, rosin maleic, carnauba, shellac, and shellac–carnauba mixture did not significantly reduce the strain Z1 yield on orange fruit surfaces compared to other waxes. With the exception of rosin maleic wax, none of the commercial fruit waxes or mixture increased significantly the ability of the formulated product of strain Z1 to control the postharvest pathogen Penicillium italicum on wounded orange fruit. When the formulated product of strain Z1 was used in combination with beeswax, strain Z1 retained the same efficacy. In contrast, microcrystalline, ester gum, candelilla, montan, paraffin, rice bran, carnauba, shellac, and shellac-carnauba mixture significantly reduced the effectiveness of the formulated product of strain Z1. No antibiosis was detected for strain Z1 against P. italicum. Strain Z1 inhibited the spore germination for the low juice concentration (up to 5%) when compared to the control. However, the addition of fresh juice after antagonist removal allowed the restoration of the germination of P. italicum spores; suggesting the possibility of competition for nutrients in the biocontrol activity of strain Z1. The study demonstrates the potential commercial application of strain Z1 with beeswax and rosin maleic wax for postharvest control of citrus blue mold. As biocontrol relies on competition for nutrients, an enriched formulation with nutrients is needed for reliable antifungal activity of this yeast strain.

Select biofungicides and fungicides, used alone or with cultivar resistance or crop rotation, were assessed for their potential in integrated management of clubroot disease. The synthetic fungicides pentachloronitrobenzene, fluazinam and cyazofamid showed activities against Plasmodiophora brassicae. The biofungicides Serenade® and Prestop® also suppressed the disease on canola via antibiosis and induced host resistance under controlled-environment conditions. Granular and seed-treatment formulations were developed to facilitate the delivery of biofungicide in field trials. Where P. brassicae resting spore populations were large in the soil, neither biofungicides nor synthetic fungicides were sufficiently effective when applied in the seed furrow. They occasionally reduced clubroot severity on Chinese cabbage. More than 5000 soil microbial isolates indigenous to the Canadian prairies were screened for potential clubroot control, but none showed consistent efficacy. Resistant cultivars reduced clubr...

The mechanism of the biofungicide Prestop (Clonostachys rosea) was investigated for control of clubroot (Plasmodio-phora brassicae) on canola. The key product components were partitioned and assessed for their effect on pathogen rest-ing spores, root hair infection (RHI) and disease development using light microscopy, quantitative PCR and differentapplication treatments during infection. The whole product of Prestop was consistently more effective than the C. roseaconidial suspension or product filtrate alone in reducing RHI and clubroot development. This biofungicide showed littleeffect on germination or viability of resting spores. Two-application treatments at seeding and 7–14 days after seedingachieved greater clubroot control than a single application of the biofungicide at either seeding or post-seeding stage.This may indicate the need to maintain a high biofungicide dose in the soil during primary and secondary infection. Thisbiocontrol fungus colonized the rhizosphere and interior of canola roots extensively, and possibly induced plant resis-tance based on up-regulation of the genes that are involved in jasmonic acid (BnOPR2), ethylene (BnACO) and phenyl-propanoid (BnOPCL, BnCCR) biosynthetic pathways. It is concluded that the biofungicide Prestop suppressed clubrooton canola at least via root colonization and induced systemic resistance (ISR), and the latter may be through the modu-lation of phenylpropanoid and jasmonic acid/ethylene metabolic pathways elicited by the fungus.Keywords: biological control, Brassica napus, ISR, PR protein, SAR

The aim of this work was to develop a semi-selective medium for recovery and enumeration of Pichia guilliermondii strain Z1, a reliable biocontrol agent against postharvest pathogens of citrus fruit, and to assess the population dynamic of this antagonistic yeast on orange fruit in relation to incubation temperature and time of incubation. PDA is the basal medium used in this study which allows the antagonistic strain Z1 source of carbon and nutrients. Different chemicals (thiophanate-methyl, thiabendazole, thiram and imazalil) and antibiotics (hygromycin, tetracyclin, ampicillin and chloramphenicol) have been tested individually and based on the plating efficiency up to 90%, 40 combinations have been assayed between antibiotics and fungicides. Ten combinations proved to be highly selective against citrus pathogens and laboratory microflora, but only one consisting of tetracyclin (1 g/L) and thiabendazole (60 mg/L) was retained based on plating efficiency up to 99%, total selectivity against laboratory microflora, epiphytic microflora from washed orange fruit and lower cost. The semi-selective medium TET-TBZ-PDA has been used to assess the impact of temperature and incubation time on the survival of strain Z1. It appears that population density was significantly influenced by both factors and the highest population size was recorded at 25°C followed by 5 and 35°C, respectively. This strain required a time of adaptation before entering the exponential growth phase with a maximum growth observed at 25°C relative to others. The semi-selective medium TET-TBZ-PDA could be an efficient and valuable way to track the population density of this strain on the surface of orange when applied pre-or postharvest. This semi-selective medium may also aid in reaching a population density allowing a better efficiency in relation to environmental conditions. Key words: Antibiotics, biocontrol, citrus, fungicides, quantification, plating efficiency,Pichia guilliermondii strain Z1, semi-selective medium.

Fusarium head blight (FHB) is a serious disease of wheat worldwide. Cultivar resistance to FHB depends on biochemical factors that confine the pathogen spread in spikes. Breeding for cultivar resistance is considered the most practical way to manage this disease. In this study, different spectroscopy and microscopy techniques were applied to discriminate resistance in wheat genotypes against FHB. Synchrotron-based spectroscopy and imaging techniques, including focal plane array infrared and X-ray fluorescence (XRF) spectroscopy were used to understand changes in biochemical and trace elements in rachis following FHB infection. Sumai3 and Muchmore were used to represent resistant and susceptible cultivars to FHB, respectively, in this study. The histological comparison of rachis showed substantial differences in the cell wall thickness between the cultivars after infection. Synchrotron-based infrared imaging emphasized substantial difference in biochemical composition of rachis samples between the two cultivars prior to visible symptoms; in the resistant Sumai3, infrared bands representing alkyl ester, cellulose and lignin vibrations as well as amide I, pectin, cellulose, hemicellulose, and aromatics group were stronger and more persistent compared to the susceptible cultivar. These bands may be the candidates of biochemical markers for FHB resistance. Focal plane array infrared imaging (FPA) spectra from the rachis epidermis and vascular bundles revealed a new band (1710 cm-1) related to the oxidative stress on the susceptible cultivar only. XRF spectroscopy data revealed differences in trace elemental composition between cultivars, and between non-inoculated and inoculated samples, with substantial increases observed for Ca, K, Mn, Fe, Zn, and Si in the resistant cultivar. These trace elements are related to cell wall stability, metabolic process, and plant defense mechanisms such as lignification pathway and callose deposition. The combination of cell wall elemental composition and lignification plays a role in the mechanism of type II host resistance to FHB. Biochemical profiling using the synchrotron-based spectroscopy holds potential for screening wheat genotypes for FHB resistance.

Clubroot is a serious threat to canola production in western Canada. The biofungicide Serenade® (Bacillus subtilis QST713) reduced the disease substantially in controlled environment, but showed variable efficacy in field trials. To better understand how this biofungicide works, two of the product components, i.e., B. subtilis and its metabolites (product filtrate), were assessed under controlled conditions for their relative contribution to clubroot control. The information may be used to optimize the product formulation. The bacterium or product filtrate alone was only partially effective against clubroot, reducing disease severity by about 60% relative to untreated controls. In contrast, Serenade controlled the disease by over 90%. This pattern of response was mirrored in quantitative PCR assessment on P. brassicae DNA within canola roots; the lowest and highest amounts of pathogen DNA were found in roots of Serenade treatment (0.02 and 0.01 ng/g) and controls (0.52 and 13.35 ng/g), respective...

Clubroot caused by Plasmodiophora brassicae is an emerging threat to canola (Brassica napus) production in western Canada, and a serious disease on crucifer vegetable crops in eastern Canada. In this study, seven biological control agents and two fungicides were evaluated as soil drenches or seed treatments for control of clubroot. Under growth cabinet conditions, a soil-drench application of formulated biocontrol agents Bacillus subtilis and Gliocladium catenulatum reduced clubroot severity by more than 80% relative to pathogen-inoculated controls on a highly susceptible canola cultivar. This efficacy was similar to that of the fungicides fluazinam and cyazofamid. Under high disease pressure in greenhouse conditions, the biocontrol agents were less effective than the fungicides. Additionally, all of the treatments delivered as a seed coating were less effective than the soil drench. In field trials conducted in 2009, different treatments consisting of a commercial formulation of B. subtilis, G. catenulatum, fluazinam or cyazofamid were applied as an in-furrow drench at 500 L ha−1 water volume to one susceptible and one resistant cultivar at two sites seeded to canola in Alberta and one site of Chinese cabbage in Ontario. There was no substantial impact on the susceptible canola cultivar, but all of the treatments reduced clubroot on the susceptible cultivar of Chinese cabbage, lowering disease severity by 54–84%. There was a period of 4 weeks without rain after the canola was seeded, which likely contributed to the low treatment efficacy on canola. Under growth cabinet conditions, fluazinam and B. subtilis products became substantially less effective after 2 weeks in a dry soil, but cyazofamid retained its efficacy for at least 4 weeks.

This study investigated the influence of UV-B radiation (280‐320 nm) on survival of Candida oleophila strain O, an antagonist yeast that prevents postharvest diseases caused by Botrytis cinerea and Penicillium expansum on apple and pear fruits. Lethal doses (LD50 and LD90) were, respectively, 0AE89 and 1AE45 Kj m )2 for in vitro exposure and 3AE06 and 5AE 5K j m )2 for in vivo exposure. A screening test of UV-B protectants for strain O was also evaluated under in vitro and in vivo conditions. The in vitro results showed that sodium ascorbate (0AE1% and 0AE01%), riboflavin (0AE1%) and uric acid (0AE1% and 0AE01%) were the most effective and most suitable protectants. However, only riboflavin (0AE1%) and uric acid (0AE1%) were effective under in vivo conditions. The efficacy obtained with strain O against P. expansum, when subjected to UV-B radiation, was 75AE0% and 49AE2% for pathogen concentrations of 10 5 and 10 6 spores mL )1 , respectively. Adding riboflavin to strain O gave a similar efficacy (64AE2%). Applying strain O together with uric acid (0AE1%) was less active (47AE7%). Nonetheless, its efficacy when applied with the antioxidants sodium ascorbate (71AE1%) or ascorbic acid (82AE5%) was the greatest. Riboflavin and uric acid were the most cost-effective protectants, and could be included in thefinal formulation of strain O when applied preharvest.

Sugar beet (Beta vulgaris) is one of most important industrial crops in Morocco. In 2016, the cultivated area exceeded 61,000 ha and it's anticipated that this area will increase to 77,500 ha by 2020. However, sugarbeet yield is often…

The objective of this work is to evaluate the ability of some additive substances in protecting the biocontrol agent Candida oleophila (strain O) against the adverse effects of environmental factors, such as water activity (aw, 0.93 and 0.98) and relative humidity (75% and 98%). The protection obtained with various protectant substances, skimmed milk (SM), peptone, maltose, sucrose, sorbitol, lactose and polyethylene glycol was assayed under in vitro and in vivo conditions. The yeast cells with the highest level of protecting agents (1%) had higher viability than those with low protectant levels (0.1% and 0.5%). SM, sucrose and sorbitol improved significantly the C. oleophila survival on apple fruit surface by 80.8%, 42.26% and 37.27% and gave a significant protection (from 96% to 100%) against Penicillium expansum under dried conditions. The highest strain O density and efficacy was obtained with SM. Under experimental conditions reflecting practical conditions, SM applied in combination with the strain O resulted in improved biocontrol efficacy by 74.65%. Therefore, SM could be used as material substrate with the best sugar protectants during the formulation process of this antagonistic yeast for eventual pre-harvest application.

The yeast Pichia anomala strain K was selected in Belgium from the apple surface for its antagonistic activity against post-harvest diseases of apples. The efficacy of this strain against P. expansum was evaluated in the laboratory in three scenarios designed to mimic practical conditions, with different periods of incubation between biological treatment, wounding of fruit surface, and pathogen inoculation. Higher protection levels and higher final yeast densities were obtained when the applied initial concentration was 1 × 108 cfu ml−1 than when it was only 1 × 105 cfu ml−1. The protection level correlated positively with the yeast density determined in wounds and was influenced by apple surface wetness. In orchard trials spanning two successive years, biological treatment against P. expansum, based on a powder of P. anomala strain K (1 × 107 cfu ml−1), β-1,3-glucans (YGT 2 g l−1), and CaCl2.2H20 (20 g l−1), was applied to apples pre- or post-harvest under practical conditions and its effect compared with standard chemical treatments. The first year, the highest reduction (95.2%) against blue decay was obtained by means of four successive fungicide treatments and the next-highest level (87.6%) with pre-harvest high-volume spraying of the three-component mixture 12 days before harvest. The second year, the best results were obtained with post-harvest Sumico (carbendazim 25% and diethofencarb 25%) treatment and post-harvest biological treatment, both by dipping the apples, 88.3 and 56.3% respectively. A density threshold of 1 × 104 cfu cm−2 of strain K on the apple surface seemed to be required just after harvest for high protective activity, whatever the method and time of application. In the case of pre-harvest biological treatments, variations in meteorological conditions between the 2 years may have considerably affected strain K population density and its efficacies.

Aims: To evaluate the influence of environmental parameters (water activity aw, temperature, and pH) on the radial growth rate of Trichoderma asperellum (strains PR10, PR11, PR12, and 659-7), an antagonist of Phytophthora megakarya, the causal agent of cocoa black pod disease. Methods and Results: The radial growth of four strains of T. asperellum was monitored for 30 days on modified PDA medium. Six levels of aw (0AE995, 0AE980, 0AE960, 0AE930, 0AE910, and 0AE880) were combined with three values of pH (4AE5, 6AE5, and 8AE5) and three incubation temperatures (20, 25, and 30� C). Whatever the strain, mycelial growth rate was optimal at aw between 0AE995 and 0AE980, independently of the temperature and pH. Each strain appeared to be very sensitive to aw reduction. In addition, all four strains were able to grow at all temperatures and pH values (4AE5‐8AE5) tested, highest growth rate being observed at 30� C and at pH 4AE5‐6AE5. The use of response surface methodology to model the combined effects of aw, temperature, and pH on the radial growth rate of the T. asperellum strains confirmed the observed results. In our model, growth of the T. asperellum strains showed a greater dependence on aw than on temperature or pH under in vitro conditions. Conclusions: aw is a crucial environmental factor. Low aw can prevent growth of T. asperellum strains under some conditions. The observed and predicted radial growth rate of strain PR11 showed its greater capacity to support low aw (0AE93) as compared with other tested strains at 20� C. This is in agreement with its better protective level when applied in medium-scale trials on cocoa plantations. Significance and Impact of the Study: This study should contribute towards improving the biocontrol efficacy of T. asperellum strains used against P. megakarya. Integrated into a broader study of the impact of environmental factors on the biocontrol agent‐pathogen system, this work should help to build a more rational control strategy, possibly involving the use of a compatible adjuvant protecting T. asperellum against desiccation.

The objective of this work was to develop validated models predicting the 'in vitro' effect of a(w) and temperature on the radial growth of Botrytis cinerea. The growth rate (g, mm d(-1)) of B. cinerea was calculated at three incubation temperatures (25 degrees C, 15 degrees C, 5 degrees C) and six water activities (ranging from 0.995 to 0.890). The water activity was adjusted with glucose, NaCl, glycerol, or sorbitol. Statistical analysis showed a significant effect of temperature, solute, a(w), and their two- and three-way interactions on the growth rate. No growth was observed at a(w)=0.93 in the presence of NaCl or at 0.89 in the presence of a non-ionic solute. The maximum colony growth rate decreased when the incubation temperature and water activity was lowered. Secondary models, relating the colony growth rate with a(w) or a(w) and temperature were developed. Optimum a(w) values for growth ranged from 0.981 to 0.987 in glycerol-, sorbitol-, or glucose-modified medium and were close to 1 in NaCl-modified medium. A quadratic polynomial equation was used to describe the combined effects of temperature and a(w) on g (mm d(-1)) in the presence of each solute. The highest and lowest radial growth rates were observed in models based on glucose and NaCl respectively, whatever the incubation temperature. All models prove to be good predictors of the growth rates of B. cinerea within the limits of experiments. The quadratic polynomial equation has bias factors of 0.957, 1.036, 0.950, and 0.860 and accuracy factors of 1.089, 1.070, 1.120 and 1.260 in media supplemented with glucose, NaCl, glycerol and sorbitol respectively. The results from modelling confirm the general finding that a(w) has a greater influence on fungal growth than temperature.

The effect of solutes, water activity (a(w), 0.890--0.980) and temperature (5--25 degrees C) on the mycelial growth rate of Penicillium expansum was evaluated. The growth rate dropped as the temperature and a(w) of the medium decreased. NaCl was the solute causing the greatest growth rate reduction, followed by glucose, glycerol and sorbitol. Statistical analysis of the results showed a significant effect of solute, a(w), temperature and combinations of two or three of these factors (P0.0001). Whatever the solutes and a(w) values, the initiation of colony growth required an additional day at 15 degrees C and 5 degrees C as compared to initiation at 25 degrees C. Growth models based on the results obtained with sorbitol and glycerol differed only slightly, with R(2) values of 97.00% and 97.95%, respectively. The response surfaces of both quadratic polynomial models showed that P. expansum should be able to grow at low a(w) (0.890) and that growth at 25 degrees C should be fastest at a(w) values ranging from 0.960 to 0.980. Both models presented a good fit between predicted and observed values.

The effect of a high electric field on secondary structure conformation of fully hydrated (45.65% wet basis) gluten protein was studied by Fourier transform infrared spectroscopy. Three experimental conditions were evaluated including electric field intensity of 0 kV (no treatment), 3.5 kV, and 7kV and treatment time of 30, 60, and 90 min. Fourier transform infrared spectra of treated and non-treated hydrated gluten protein revealed that high electric field treatment resulted in irreversible changes in the secondary structures. For the 30 min treatment no variation was observed for electric field intensities 0 and 7 kV; but at 3.5 kV it showed slight reorganization and structural conversion of secondary structures. No variation in spectral pattern was observed for all the high electric field treatments for 60 min but major secondary structure reorganization took place for high electric field treatment at 90 min. Curve-fitting using Gaussian band shapes and principal component analysis further supported the results.

Nitrogen (N) is one of the most limiting factors for maize (Zea mays L.) production worldwide. Over-fertilization of N may decrease yields and increase NO3− contamination of water. However, low N fertilization will decrease yields. The objective is to optimize the use of N fertilizers, to excel in yields and preserve the environment. The knowledge of factors affecting the mobility of N in the soil is crucial to determine ways to manage N in the field. Researchers developed several methods to use N efficiently relying on agronomic practices, the use of sensors and the analysis of digital images. These imaging sensors determine N requirements in plants based on changes in Leaf chlorophyll and polyphenolics contents, the Normalized Difference Vegetation Index (NDVI), and the Dark Green Color index (DGCI). Each method revealed limitations and the scope of future research is to draw N recommendations from the Dark Green Color Index (DGCI) technology. Results showed that more effort is needed to develop tools to benefit from DGCI.

Background The protist Plasmodiophora brassicae is a biotrophic soil-borne pathogen that causes clubroot on Brassica crops worldwide. Clubroot disease is a serious threat to the 8 M ha of canola (Brassica napus) grown annually in western Canada. While host resistance is the key to clubroot management, sources of resistance are limited. Results To identify new sources of clubroot resistance (CR), we fine mapped a CR gene (Rcr1) from B. rapa ssp. chinensis to the region between 24.26 Mb and 24.50 Mb on the linkage group A03, with several closely linked markers identified. Transcriptome analysis was conducted using RNA sequencing on a segregating F1 population inoculated with P. brassicae, with 2,212 differentially expressed genes (DEGs) identified between plants carrying and not carrying Rcr1. Functional annotation of these DEGs showed that several defense-related biological processes, including signaling and metabolism of jasmonate and ethylene, defensive deposition of callose and biosynthesis of indole-containing compounds, were up-regulated significantly in plants carrying Rcr1 while genes involved in salicylic acid metabolic and signaling pathways were generally not elevated. Several DEGs involved in metabolism potentially related to clubroot symptom development, including auxin biosynthesis and cell growth/development, showed significantly lower expression in plants carrying Rcr1. Conclusion The CR gene Rcr1 and closely linked markers will be highly useful for breeding new resistant canola cultivars. The identification of DEGs between inoculated plants carrying and not carrying Rcr1 is an important step towards understanding of specific metabolic/signaling pathways in clubroot resistance mediated by Rcr1. This information may help judicious use of CR genes with complementary resistance mechanisms for durable clubroot resistance. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1166) contains supplementary material, which is available to authorized users.

Background Fusarium head blight (FHB), a scab principally caused by Fusarium graminearum Schw., is a serious disease of wheat. The purpose of this study is to evaluate the potential of combining synchrotron based phase contrast X-ray imaging (PCI) with Fourier Transform mid infrared (FTIR) spectroscopy to understand the mechanisms of resistance to FHB by resistant wheat cultivars. Our hypothesis is that structural and biochemical differences between resistant and susceptible cultivars play a significant role in developing resistance to FHB. Results Synchrotron based PCI images and FTIR absorption spectra (4000–800 cm−1) of the floret and rachis from Fusarium-damaged and undamaged spikes of the resistant cultivar ‘Sumai3’, tolerant cultivar ‘FL62R1’, and susceptible cultivar ‘Muchmore’ were collected and analyzed. The PCI images show significant differences between infected and non-infected florets and rachises of different wheat cultivars. However, no pronounced difference between non-inoculated resistant and susceptible cultivar in terms of floret structures could be determined due to the complexity of the internal structures. The FTIR spectra showed significant variability between infected and non-infected floret and rachis of the wheat cultivars. The changes in absorption wavenumbers following pathogenic infection were mostly in the spectral range from 1800–800 cm−1. The Principal Component Analysis (PCA) was also used to determine the significant chemical changes inside floret and rachis when exposed to the FHB disease stress to understand the plant response mechanism. In the floret and rachis samples, PCA of FTIR spectra revealed differences in cell wall related polysaccharides. In the florets, absorption peaks for Amide I, cellulose, hemicellulose and pectin were affected by the pathogenic fungus. In the rachis of the wheat cultivars, PCA underlines significant changes in pectin, cellulose, and hemicellulose characteristic absorption spectra. Amide II and lignin absorption peaks, persistent in the rachis of Sumai3, together with increased peak shift at 1245 cm−1 after infection with FHB may be a marker for stress response in which the cell wall compounds related to pathways for lignification are increased. Conclusions Synchrotron based PCI combined with FTIR spectroscopy show promising results related to FHB in wheat. The combined technique is a powerful new tool for internal visualisation and biomolecular monitoring before and during plant-microbe interactions to understand both the differences between cultivars and their different responses to disease stress. Electronic supplementary material The online version of this article (doi:10.1186/s12870-014-0357-5) contains supplementary material, which is available to authorized users.

Aims: To evaluate the effect of water activity (aw 0·98–0·89, adjusted with glycerol, sorbitol, glucose, or NaCl) and temperature (5–25°C) on the lag phase and radial growth rate (mm day−1) of the important citrus spoilage fungi, such as Penicillium italicum and Penicillium digitatum grown in potato dextrose agar (PDA) medium. To select, among models based on the use of different solutes, a model fitting accurately the growth of these species in relation to aw and temperature. Methods and Results: Extensive data analyses showed for both Penicillium species a highly significant effect of aw, temperature, solutes and their interactions on radial growth rate (P