Utilizing the Banana S-Adenosyl-L-Homocysteine Hydrolase Allergen to Identify Cross-Reactive IgE in Ryegrass-, Latex-, and Kiwifruit-Allergic Individuals.

Food allergies mediated by specific IgE (sIgE) have a significant socioeconomic impact on society. Evaluating the IgE cross-reactivity between allergens from different allergen sources can enable the better management of these potentially life-threatening adverse reactions to food proteins and enhance food safety. A novel banana fruit allergen, S-adenosyl-L-homocysteine hydrolase (SAHH), has been recently identified and its recombinant homolog was heterologously overproduced in E. coli. In this study, we performed a search in the NCBI (National Center for Biotechnology Information) for SAHH homologs in ryegrass, latex, and kiwifruit, all of which are commonly associated with pollen-latex-fruit syndrome. In addition, Western immunoblot analysis was utilized to identify the cross-reactive IgE to banana SAHH in the sera of patients with a latex allergy, kiwifruit allergy, and ryegrass allergy. ClustalOmega analysis showed more than 92% amino acid sequence identity among the banana SAHH homologs in ryegrass, latex, and kiwifruit. In addition to five B-cell epitopes, in silico analysis predicted eleven T-cell epitopes in banana SAHH, seventeen in kiwifruit SAHH, twelve in ryegrass SAHH, and eight in latex SAHH, which were related to the seven-allele HLA reference set (HLA-DRB1*03:01, HLA-DRB1*07:01, HLA-DRB1*15:01, HLA-DRB3*01:01, HLA-DRB3*02:02, HLA-DRB4*01:01, HLA-DRB5*01:01). Four T-cell epitopes were identical in banana and kiwifruit SAHH (positions 328, 278, 142, 341), as well as banana and ryegrass SAHH (positions 278, 142, 96, and 341). All four SAHHs shared two T-cell epitopes (positions 278 and 341). In line with the high amino acid sequence identity and B-cell epitope homology among the analyzed proteins, the cross-reactive IgE to banana SAHH was detected in three of three latex-allergic patients, five of six ryegrass-allergic patients, and two of three kiwifruit-allergic patients. Although banana SAHH has only been studied in a small group of allergic individuals, it is a novel cross-reactive food allergen that should be considered when testing for pollen-latex-fruit syndrome.

Genetic mapping of Fusarium wilt resistance in a wild banana Musa acuminata ssp. malaccensis accession.

Banana is an important fruit and food crop, but is threatened by Fusarium wilt, one of the most devastating soil-borne fungal diseases. Only host resistance facilitates banana cultivation in infested soils around the world, but the genetic basis of Fusarium wilt of banana (FWB) is unknown. We selfed a heterozygous wild banana accession Musa acuminata ssp. malaccensis (Mam, AA, 2n = 22) to generate a mapping population and to investigate the inheritance of resistance to Race 1 and tropical race 4 (TR4) that cause FWB. Phenotyping (N = 217) revealed segregation for resistance, and genotyping by sequencing resulted in 2802 high-quality single-nucleotide polymorphic markers (SNPs) that were used for genetic mapping. Combined analyses of these data showed that a single dominant resistance locus controls resistance to Race 1 and maps near the distal part of chromosome 10. Recombinants, together with the position of the putative resistance gene, were further analysed using graphical genotyping, which retrieved markers flanking a 360 kb genetic region that associates with Race 1 resistance. The region contains 165 putative genes on the reference genome, including 19 leucine-rich repeat receptor-like kinase-like genes. At the same position and phase, we also identified a QTL for TR4 resistance, showing that the locus for resistance against Race 1 provided partial resistance to TR4. However, this effect was far less significant and hence not included in the mapping. These data support the breeding of new banana varieties with resistance to Fusarium wilt.

The Novel Cerato-Platanin-Like Protein FocCP1 from Fusarium oxysporum Triggers an Immune Response in Plants.

Panama disease, or Fusarium wilt, the most serious disease in banana cultivation, is caused by Fusarium oxysporum f. sp. cubense (FOC) and has led to great economic losses worldwide. One effective way to combat this disease is by enhancing host plant resistance. The cerato-platanin protein (CPP) family is a group of small secreted cysteine-rich proteins in filamentous fungi. CPPs as elicitors can trigger the immune system resulting in defense responses in plants. In this study, we characterized a novel cerato-platanin-like protein in the secretome of Fusarium oxysporum f. sp. cubense race 4 (FOC4), named FocCP1. In tobacco, the purified recombinant FocCP1 protein caused accumulation of reactive oxygen species (ROS), formation of necrotic reaction, deposition of callose, expression of defense-related genes, and accumulation of salicylic acid (SA) and jasmonic acid (JA) in tobacco. These results indicated that FocCP1 triggered a hypersensitive response (HR) and systemic acquired resistance (SAR) in tobacco. Furthermore, FocCP1 enhanced resistance tobacco mosaic virus (TMV) disease and Pseudomonas syringae pv. tabaci 6605 (Pst. 6605) infection in tobacco and improved banana seedling resistance to FOC4. All results provide the possibility of further research on immune mechanisms of plant and pathogen interactions, and lay a foundation for a new biological strategy of banana wilt control in the future.

Banana lectin (BanLec) induces non-specific activation of basophils and mast cells in atopic subjects.

Summary: Dietary lectins play a major role in the activation of mast cells / basophils by bridging cell surface IgE glycans to release histamine and other mediators. In the present study, the effect of mannose / glucose-specific banana lectin (BanLec) on the activation of mast cells / basophils from non-atopic and atopic subjects has been investigated. BanLec was purified from banana pulp in a yield of 7 mg/kg. Leukocytes isolated from heparinized blood of non-atopic / atopic subjects were used for quantitation of the released histamine. Approximately 28.2% of the atopics (n = 117) was positive by skin prick test (SPT) to purified BanLec (100 µg/mL concentration), and all the non-atopics (n = 20) were negative. Maximal release of histamine was seen at 2 µg of BanLec. In percent histamine release, an increase of 35-40% is observed in case of atopics (n = 7) compared to non-atopics (n = 5), and the histamine release from atopic and non-atopic subjects correlates fairly well with the total serum IgE levels (R2 = 0.817). BanLec also induces release of histamine (26.7%) from mast cells present in rat peritoneal exudate cells. BanLec can significantly activate and degranulate mast cells and basophils by cross-linking the trimannosidic core mannose of IgE glycans in atopic population as compared to non-atopic population; the activation is marginal in the case of non-atopics.

Activation of salicylic acid metabolism and signal transduction can enhance resistance to Fusarium wilt in banana (Musa acuminata L. AAA group, cv. Cavendish).

Fusarium wilt caused by the fungus Fusarium oxysporum f. sp. cubens (Foc) is the most serious disease that attacks banana plants. Salicylic acid (SA) can play a key role in plant-microbe interactions. Our study is the first to examine the role of SA in conferring resistance to Foc TR4 in banana (Musa acuminata L. AAA group, cv. Cavendish), which is the greatest commercial importance cultivar in Musa. We used quantitative real-time reverse polymerase chain reaction (qRT-PCR) to analyze the expression profiles of 45 genes related to SA biosynthesis and downstream signaling pathways in a susceptible banana cultivar (cv. Cavendish) and a resistant banana cultivar (cv. Nongke No. 1) inoculated with Foc TR4. The expression of genes involved in SA biosynthesis and downstream signaling pathways was suppressed in a susceptible cultivar and activated in a resistant cultivar. The SA levels in each treatment arm were measured using high-performance liquid chromatography. SA levels were decreased in the susceptible cultivar and increased in the resistant cultivar. Finally, we examined the contribution of exogenous SA to Foc TR4 resistance in susceptible banana plants. The expression of genes involved in SA biosynthesis and signal transduction pathways as well as SA levels were significantly increased. The results suggest that one reason for banana susceptibility to Foc TR4 is that expression of genes involved in SA biosynthesis and SA levels are suppressed and that the induced resistance observed in banana against Foc TR4 might be a case of salicylic acid-dependent systemic acquired resistance.

Evasion of short interfering RNA-directed antiviral silencing in Musa acuminata persistently infected with six distinct banana streak pararetroviruses.

UNLABELLED: Vegetatively propagated crop plants often suffer from infections with persistent RNA and DNA viruses. Such viruses appear to evade the plant defenses that normally restrict viral replication and spread. The major antiviral defense mechanism is based on RNA silencing generating viral short interfering RNAs (siRNAs) that can potentially repress viral genes posttranscriptionally through RNA cleavage and transcriptionally through DNA cytosine methylation. Here we examined the RNA silencing machinery of banana plants persistently infected with six pararetroviruses after many years of vegetative propagation. Using deep sequencing, we reconstructed consensus master genomes of the viruses and characterized virus-derived and endogenous small RNAs. Consistent with the presence of endogenous siRNAs that can potentially establish and maintain DNA methylation, the banana genomic DNA was extensively methylated in both healthy and virus-infected plants. A novel class of abundant 20-nucleotide (nt) endogenous small RNAs with 5'-terminal guanosine was identified. In all virus-infected plants, 21- to 24-nt viral siRNAs accumulated at relatively high levels (up to 22% of the total small RNA population) and covered the entire circular viral DNA genomes in both orientations. The hotspots of 21-nt and 22-nt siRNAs occurred within open reading frame (ORF) I and II and the 5' portion of ORF III, while 24-nt siRNAs were more evenly distributed along the viral genome. Despite the presence of abundant viral siRNAs of different size classes, the viral DNA was largely free of cytosine methylation. Thus, the virus is able to evade siRNA-directed DNA methylation and thereby avoid transcriptional silencing. This evasion of silencing likely contributes to the persistence of pararetroviruses in banana plants. IMPORTANCE: We report that DNA pararetroviruses in Musa acuminata banana plants are able to evade DNA cytosine methylation and transcriptional gene silencing, despite being targeted by the host silencing machinery generating abundant 21- to 24-nucleotide short interfering RNAs. At the same time, the banana genomic DNA is extensively methylated in both healthy and virus-infected plants. Our findings shed light on the siRNA-generating gene silencing machinery of banana and provide a possible explanation why episomal pararetroviruses can persist in plants whereas true retroviruses with an obligatory genome-integration step in their replication cycle do not exist in plants.

Plant defense response against Fusarium oxysporum and strategies to develop tolerant genotypes in banana.

Soil-borne fungal pathogen, Fusarium oxysporum causes major economic losses by inducing necrosis and wilting symptoms in many crop plants. Management of fusarium wilt is achieved mainly by the use of chemical fungicides which affect the soil health and their efficiency is often limited by pathogenic variability. Hence understanding the nature of interaction between pathogen and host may help to select and improve better cultivars. Current research evidences highlight the role of oxidative burst and antioxidant enzymes indicating that ROS act as an important signaling molecule in banana defense response against Fusarium oxysporum f.sp. cubense. The role of jasmonic acid signaling in plant defense against necrotrophic pathogens is well recognized. But recent studies show that the role of salicylic acid is complex and ambiguous against necrotrophic pathogens like Fusarium oxysporum, leading to many intriguing questions about its relationship between other signaling compounds. In case of banana, a major challenge is to identify specific receptors for effector proteins like SIX proteins and also the components of various signal transduction pathways. Significant progress has been made to uncover the role of defense genes but is limited to only model plants such as Arabidopsis and tomato. Keeping this in view, we review the host response, pathogen diversity, current understanding of biochemical and molecular changes that occur during host and pathogen interaction. Developing resistant cultivars through mutation, breeding, transgenic and cisgenic approaches have been discussed. This would help us to understand host defenses against Fusarium oxysporum and to formulate strategies to develop tolerant cultivars.

Transgenic expression of the rice Xa21 pattern-recognition receptor in banana (Musa sp.) confers resistance to Xanthomonas campestris pv. musacearum.

Banana Xanthomonas wilt (BXW), caused by the bacterium Xanthomonas campestris pv. musacearum (Xcm), is the most devastating disease of banana in east and central Africa. The spread of BXW threatens the livelihood of millions of African farmers who depend on banana for food security and income. There are no commercial chemicals, biocontrol agents or resistant cultivars available to control BXW. Here, we take advantage of the robust resistance conferred by the rice pattern-recognition receptor (PRR), XA21, to the rice pathogen Xanthomonas oryzae pv. oryzae (Xoo). We identified a set of genes required for activation of Xa21-mediated immunity (rax) that were conserved in both Xoo and Xcm. Based on the conservation, we hypothesized that intergeneric transfer of Xa21 would confer resistance to Xcm. We evaluated 25 transgenic lines of the banana cultivar 'Gonja manjaya' (AAB) using a rapid bioassay and 12 transgenic lines in the glasshouse for resistance against Xcm. About 50% of the transgenic lines showed complete resistance to Xcm in both assays. In contrast, all of the nontransgenic control plants showed severe symptoms that progressed to complete wilting. These results indicate that the constitutive expression of the rice Xa21 gene in banana results in enhanced resistance against Xcm. Furthermore, this work demonstrates the feasibility of PRR gene transfer between monocotyledonous species and provides a valuable new tool for controlling the BXW pandemic of banana, a staple food for 100 million people in east Africa.

Phenylpropanoid pathway is potentiated by silicon in the roots of banana plants during the infection process of Fusarium oxysporum f. sp. cubense.

Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense, is a disease that causes large reductions in banana yield worldwide. Considering the importance of silicon (Si) to potentiate the resistance of several plant species to pathogen infection, this study aimed to investigate, at the histochemical level, whether this element could enhance the production of phenolics on the roots of banana plants in response to F. oxysporum f. sp. cubense infection. Plants of cultivar Maçã, which is susceptible to F. oxysporum f. sp. cubense, were grown in plastic pots amended with 0 (-Si) or 0.39 g of Si (+Si) per kilogram of soil and inoculated with race 1 of F. oxysporum f. sp. cubense. The root Si concentration was increased by 35.6% for +Si plants in comparison to the -Si plants, which contributed to a 27% reduction in the symptoms of Fusarium wilt on roots. There was an absence of fluorescence for the root sections of the -Si plants treated with the Neu and Wilson's reagents. By contrast, for the root sections obtained from the +Si plants treated with Neu's reagent, strong yellow-orange fluorescence was observed in the phloem, and lemon-yellow fluorescence was observed in the sclerenchyma and metaxylem vessels, indicating the presence of flavonoids. For the root sections of the +Si plants treated with Wilson's reagent, orange-yellowish autofluorescence was more pronounced around the phloem vessels, and yellow fluorescence was more pronounced around the metaxylem vessels, also indicating the presence of flavonoids. Lignin was more densely deposited in the cortex of the roots of the +Si plants than for the -Si plants. Dopamine was barely detected in the roots of the -Si plants after using the lactic and glyoxylic acid stain, but was strongly suspected to occur on the phloem and metaxylem vessels of the roots of the +Si plants as confirmed by the intense orange-yellow fluorescence. The present study provides new evidence of the pivotal role of the phenylpropanoid pathway in the resistance of banana plants to F. oxysporum f. sp. cubense infection when supplied with Si.

Adding value to banana farming: Antibody production in post-harvest leaves.

Banana, a globally popular fruit, is widely cultivated in tropical and sub-tropical regions. After fruit harvest, remaining banana plant materials are low-value byproducts, mostly composted or used as fibre or for food packaging. As an aim to potentially increase farmer income, this study explored underutilised banana biomass as a novel plant tissue for production of a high-value product. Protein scFvTG130 used in this study, is an anti-toxoplasma single chain variable fragment antibody that can be used in diagnostics and neutralising the Toxoplasma gondii pathogen. Using detached banana leaves, we investigated the factors influencing the efficacy of a transient expression system using reporter genes and recombinant protein, scFvTG130. Transient expression was optimal at 2 days after detached banana leaves were vacuum infiltrated at 0.08 MPa vacuum pressure for a duration of 3 min with 0.01% (v/v) Tween20 using Agrobacterium strain GV3101 harbouring disarmed virus-based vector pIR-GFPscFvTG130. The highest concentration of anti-toxoplasma scFvTG130 antibody obtained using detached banana leaves was 22.8 µg/g fresh leaf tissue. This first study using detached banana leaf tissue for the transient expression of a recombinant protein, successfully demonstrated anti-toxoplasma scFvTG130 antibody expression, supporting the potential application for other related proteins using an underutilised detached banana leaf tissue.

Effect of coconut palm proximities and Musa spp. germplasm resistance to colonization by Raoiella indica (Acari: Tenuipalpidae).

Although coconut (Cocos nucifera L.) is the predominant host for Raoiella indica Hirst (Acari: Tenuipalpidae), false spider mite infestations do occur on bananas and plantains (Musa spp. Colla). Since its introduction, the banana and plantain industries have been negatively impacted to different degrees by R. indica infestation throughout the Caribbean. Genetic resistance in the host and the proximity of natural sources of mite infestation has been suggested as two of the main factors affecting R. indica densities in Musa spp. plantations. Greenhouse experiments were established to try to determine what effect coconut palm proximities and planting densities had on R. indica populations infesting Musa spp. plants. Trials were carried out using potted Musa spp. and coconut palms plants at two different ratios. In addition, fourteen Musa spp. hybrid accessions were evaluated for their susceptibility/resistance to colonization by R. indica populations. Differences were observed for mite population buildup for both the density and germplasm accession evaluations. These results have potential implications on how this important pest can be managed on essential agricultural commodities such as bananas and plantains.

Apoptosis-related genes confer resistance to Fusarium wilt in transgenic 'Lady Finger' bananas.

Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), is one of the most devastating diseases of banana (Musa spp.). Apart from resistant cultivars, there are no effective control measures for the disease. We investigated whether the transgenic expression of apoptosis-inhibition-related genes in banana could be used to confer disease resistance. Embryogenic cell suspensions of the banana cultivar, 'Lady Finger', were stably transformed with animal genes that negatively regulate apoptosis, namely Bcl-xL, Ced-9 and Bcl-2 3' UTR, and independently transformed plant lines were regenerated for testing. Following a 12-week exposure to Foc race 1 in small-plant glasshouse bioassays, seven transgenic lines (2 × Bcl-xL, 3 × Ced-9 and 2 × Bcl-2 3' UTR) showed significantly less internal and external disease symptoms than the wild-type susceptible 'Lady Finger' banana plants used as positive controls. Of these, one Bcl-2 3' UTR line showed resistance that was equivalent to that of wild-type Cavendish bananas that were included as resistant negative controls. Further, the resistance of this line continued for 23-week postinoculation at which time the experiment was terminated. Using TUNEL assays, Foc race 1 was shown to induce apoptosis-like features in the roots of wild-type 'Lady Finger' plants consistent with a necrotrophic phase in the life cycle of this pathogen. This was further supported by the observed reduction in these effects in the roots of the resistant Bcl-2 3' UTR-transgenic line. This is the first report on the generation of transgenic banana plants with resistance to Fusarium wilt.

Sensitization profiles to purified plant food allergens among pediatric patients with allergy to banana.

Banana fruit allergy is well known, but neither immunoglobulin E recognition patterns to purified plant food allergens nor true prevalences of putative banana allergens have been established. This study aimed to characterize ß-1,3-glucanase and thaumatin-like protein (TLP) as banana allergens, testing them, together with other plant food allergens, in 51 children with allergic reactions after banana ingestion and both positive specific IgE and skin prick test (SPT) to banana. Banana ß-1,3-glucanase and TLP were isolated and characterized. Both banana allergens, together with kiwifruit TLP Act d 2, avocado class I chitinase Pers a 1, palm pollen profilin Pho d 2 and peach fruit lipid transfer protein (LTP) Pru p 3, were tested by in vitro and in vivo assays. Banana ß-1,3-glucanase (Mus a 5) was glycosylated, whereas banana TLP (Mus a 4) was not, in contrast with its homologous kiwi allergen Act d 2. Specific IgE to both banana allergens, as well as to peach Pru p 3, was found in over 70% of sera from banana-allergic children, and Mus a 4 and Pru p 3 provoked positive SPT responses in 6 of the 12 tested patients, whereas Mus a 5 in only one of them. Both peptidic epitopes and cross-reactive carbohydrate determinants were involved in the IgE-binding to Mus a 5, whereas cross-reactivity between Mus a 4 and Act d 2 was only based on common IgE protein epitopes. Profilin Pho d 2 elicited a relevant proportion of positive responses on in vitro (41%) and in vivo (58%) tests. Therefore, Mus a 4 and LTP behave as major banana allergens in the study population, and profilin seems to be also a relevant allergen. Mus a 5 is an equivocal allergenic protein, showing high IgE-binding to its attached complex glycan, and low in vivo potency.

Longitudinal study on specific IgE against natural rubber latex, banana and kiwi in patients with spina bifida.

OBJECTIVE: Up to 2 out of 3 spina bifida (sb) patients with natural rubber latex (NRL) antibodies (ab) have crossreacting IgE-ab against tropical fruit, due to structural homologies between several NRL antigens and allergenic fruit proteins. It is essential to investigate whether the patients were first sensitized against NRL or fruit, to give recommendations for an evidence-based prophylaxis. PATIENTS AND METHODS: We investigated sera of 96 sb patients for specific IgE ab against NRL, banana and kiwi as examples for crossreacting fruit by FEIA (ImmunoCAP System, Phadia). These tests were repeated up to 3 times (mean after 2 years, maximum after 7 years). RESULTS: In the first testing only 2 of 50 NRL-IgE negative patients (4%) had ab against banana or kiwi. 4 of the 46 NRL-IgE positive patients (8%) showed ab against banana (2) or kiwi (2), 3 (7%) against both fruit. Symptoms of fruit allergy were presented by 3 patients, all symptomatic patients had high levels of specific fruit-ab. In the follow-up study 2 patients with low sensitization against NRL lost their NRL ab and their fruit ab, another 2 only the fruit ab, whereas 4 NRL-sensitized patients newly developed ab against banana and 1 against kiwi. Only 2 patients developed ab against fruit without being sensitized against NRL. 7 out of 10 patients with banana and kiwi ab were atopics. CONCLUSIONS: In most cases the sensitization against fruit follows the NRL sensitization. There is no need to recommend sb patients without NRL sensitization to primarily avoid tropical fruit.

Isolation and characterization of nucleotide-binding site and C-terminal leucine-rich repeat-resistance gene candidates in bananas.

Commercial banana varieties are highly susceptible to fungal pathogens, as well as bacterial pathogens, nematodes, viruses, and insect pests. The largest known family of plant resistance genes encodes proteins with nucleotide-binding site (NBS) and C-terminal leucine-rich repeat (LRR) domains. Conserved motifs in such genes in diverse plant species offer a means for the isolation of candidate genes in banana that may be involved in plant defense. Six degenerate PCR primers were designed to target NBS and additional domains were tested on commercial banana species Musa acuminata subsp malaccensis and the Musa AAB Group propagated in vitro and plants maintained in a greenhouse. Total DNA was isolated by a modified CTAB extraction technique. Four resistance gene analogs were amplified and deposited in GenBank and assigned numbers HQ199833-HQ199836. The predicted amino acid sequences compared to the amino acid sequences of known resistance genes (MRGL1, MRGL2, MRGL3, and MRGL4) revealed significant sequence similarity. The presence of consensus domains, namely kinase-1a, kinase-2 and hydrophobic domain, provided evidence that the cloned sequences belong to the typical non-Toll/interleukin-1 receptor-like domain NBS-LRR gene family.

Inoculation with arbuscular mycorrhizal fungus modulates defense-related genes expression in banana seedlings susceptible to wilt disease.

Banana as an important economic crop worldwide, often suffers from serious damage caused by Fusarium oxysporum f. sp. Cubense. Arbuscular mycorrhizal (AM) fungi have been considered as one of the promising plant biocontrol agents in preventing from root pathogens. This study examined the effect of AM fungal inoculation on plant growth and differential expressions of growth- and defense-related genes in banana seedlings. Tissue-cultured seedlings of Brazilian banana (Musa acuminate Cavendish cv. Brail) were inoculated with AM fungus (Rhizophagus irregularis, Ri), and developed good mycorrhizal symbiosis from 4 to 11 weeks after inoculation with an infection rate up to 71.7% of the roots system. Microbial abundance revealed that Ri abundance in banana roots was 1.85×106 copies/ml at 11 weeks after inoculaiton. Inoculation improved plant dry weights by 47.5, 124, and 129% for stem, leaf, and the whole plant, respectively, during phosphate depletion. Among a total of 1411 differentially expressed genes (DEGs) obtained from the transcriptome data analysis, genes related to plant resistance (e.g. POD, PAL, PYR, and HBP-1b) and those related to plant growth (e.g. IAA, GH3, SAUR, and ARR8) were up-regulated in AM plants. This study demonstrates that AM fungus effectively promoted the growth of banana plants and induced defense-related genes which could help suppress wilt disease. The outcomes of this study form a basis for further study on the mechanism of banana disease resistance induced by AM fungi.

Recombinant Bet v 1-BanLec chimera modulates functional characteristics of peritoneal murine macrophages by promoting IL-10 secretion.

Allergen-specific immunotherapy (AIT) is a desensitizing treatment for allergic diseases that corrects the underlined pathological immune response to innocuous protein antigens, called allergens. Recombinant allergens employed in the AIT allowed the production of well-defined formulations that possessed consistent quality but were often less efficient than natural allergen extracts. Combining recombinant allergens with an adjuvant or immunomodulatory agent could improve AIT efficacy. This study aimed to perform structural and functional characterization of newly designed recombinant chimera composed of the Bet v 1, the major birch pollen allergen, and Banana Lectin (BanLec), TLR2, and CD14 binding protein, for the application in AIT. rBet v 1-BanLec chimera was designed in silico and expressed as a soluble fraction in Escherichia coli. Purified rBet v 1-BanLec (33.4 kDa) retained BanLec-associated biological activity of carbohydrate-binding and preserved IgE reactive epitopes of Bet v 1. The chimera revealed secondary structures with predominant ß sheets. The immunomodulatory capacity of rBet v 1-BanLec tested on macrophages showed changes in myeloperoxidase activity, reduced NO production, and significant alterations in the production of cytokines when compared to both rBanLec and rBet v 1. Comparing to rBet v 1, rBet v 1-BanLec was demonstrated to be more efficient promoter of IL-10 production as well as weaker inducer of NO production and secretion of pro-inflammatory cytokines TNFα, and IL-6. The ability of rBet v 1-BanLec to promote IL-10 in together with the preserved 3D structure of Bet v 1 part implies that the construct might exert a beneficial effect in the allergen-specific immunotherapy.

Identification of sources resistant to a virulent Fusarium wilt strain (VCG 0124) infecting Cavendish bananas.

Bananas are vital for food security in many countries, and half of banana production relies solely on 'Cavendish' (AAA), which is presently threatened by the fungal pathogen Fusarium oxysporum f. sp. cubense (Foc) tropical race 4. This particular virulent Foc strain was also found to attack other banana varieties of commercial importance. As there is no single effective management practice available so far, this study was undertaken to determine resistant sources from the genotype collection available at the ICAR-National Research Centre for Banana, Tiruchirappalli, Tamil Nadu, India for direct use by farmers and/or in breeding programmes to develop resistant hybrids. A total of 258 genotypes of different ploidies and genomic constitutions were tested against Foc race 1 (VCG 0124). In total, 19 genotypes (AA Unique-6, BB type-2, AAA Unique-1, AAA Cavendish-1, AAB Mysore-3, AAB Pome-1, AAB Plantain-4 and AAAB-1) were found to be immune; eight genotypes (AA Unique-1, BB type-3, AAA Cavendish-1, AAB Mysore-1, AAB Unique-1, AAB Plantain-1) were highly resistant; and nine genotypes (AA Unique-1, AAA Cavendish-3, AAB Silk-1, AAB Pome-4) were resistant. The genotypes that are resistant to the virulent Foc race 1 (VCG 0124) strain can be exploited directly for commercialization and/or in breeding programs to develop resistant hybrids.