Structural insights into the lipid transfer mechanism of a non-specific lipid transfer protein.

The non-specific lipid transfer proteins (nsLTPs) are multifunctional seed proteins engaged in several different physiological processes. The nsLTPs are stabilized by four disulfide bonds and exhibit a characteristic hydrophobic cavity, which is the primary lipid binding site. While these proteins are known to transfer lipids between membranes, the mechanism of lipid transfer has remained elusive. Four crystal structures of nsLTP from Solanum melongena, one in the apo-state and three myristic acid bound states were determined. Among the three lipid bound states, two lipid molecules were bound on the nsLTP surface at different positions and one was inside the cavity. The lipid-dependent conformational changes leading to opening of the cavity were revealed based on structural and spectroscopic data. The surface-bound lipid represented a transient intermediate state and the lipid ultimately moved inside the cavity through the cavity gate as revealed by molecular dynamics simulations. Two critical residues in the loop regions played possible 'gating' role in the opening and closing of the cavity. Antifungal activity and membrane permeabilization effect of nsLTP against Fusarium oxysporum suggested that it could possibly involve in bleaching out the lipids. Collectively, these studies support a model of lipid transfer mechanism by nsLTP via intermediate states.

Tetranins: new putative spider mite elicitors of host plant defense.

The two-spotted spider mite (Tetranychus urticae) is a plant-sucking arthropod herbivore that feeds on a wide array of cultivated plants. In contrast to the well-characterized classical chewing herbivore salivary elicitors that promote plant defense responses, little is known about sucking herbivores' elicitors. To characterize the sucking herbivore elicitors, we explored putative salivary gland proteins of spider mites by using an Agrobacterium-mediated transient expression system or protein infiltration in damaged bean leaves. Two candidate elicitors (designated as tetranin1 (Tet1) and tetranin2 (Tet2)) triggered early leaf responses (cytosolic calcium influx and membrane depolarization) and increased the transcript abundances of defense genes in the leaves, eventually resulting in reduced survivability of T. urticae on the host leaves as well as induction of indirect plant defenses by attracting predatory mites. Tet1 and/or Tet2 also induced jasmonate, salicylate and abscisic acid biosynthesis. Notably, Tet2-induced signaling cascades were also activated via the generation of reactive oxygen species. The signaling cascades of these two structurally dissimilar elicitors are mostly overlapping but partially distinct and thus they would coordinate the direct and indirect defense responses in host plants under spider mite attack in both shared and distinct manners.

Host-induced silencing of Mi-msp-1 confers resistance to root-knot nematode Meloidogyne incognita in eggplant.

RNA interference (RNAi)-based host-induced gene silencing (HIGS) is emerging as a novel, efficient and target-specific tool to combat phytonematode infection in crop plants. Mi-msp-1, an effector gene expressed in the subventral pharyngeal gland cells of Meloidogyne incognita plays an important role in the parasitic process. Mi-msp-1 effector is conserved in few of the species of root-knot nematodes (RKNs) and does not share considerable homology with the other phytonematodes, thereby making it a suitable target for HIGS with minimal off-target effects. Six putative eggplant transformants harbouring a single copy RNAi transgene of Mi-msp-1 was generated. Stable expression of the transgene was detected in T1, T2 and T3 transgenic lines for which a detrimental effect on RKN penetration, development and reproduction was documented upon challenge infection with nematode juveniles. The post-parasitic nematode stages extracted from the transgenic plants showed long-term RNAi effect in terms of targeted downregulation of Mi-msp-1. These findings suggest that HIGS of Mi-msp-1 enhances nematode resistance in eggplant and protect the plant against RKN parasitism at very early stage.

Genotyping by Sequencing Highlights a Polygenic Resistance to Ralstonia pseudosolanacearum in Eggplant (Solanum melongena L.).

Eggplant cultivation is limited by numerous diseases, including the devastating bacterial wilt (BW) caused by the Ralstonia solanacearum species complex (RSSC). Within the RSSC, Ralstonia pseudosolanacearum (including phylotypes I and III) causes severe damage to all solanaceous crops, including eggplant. Therefore, the creation of cultivars resistant to R. pseudosolanacearum strains is a major goal for breeders. An intraspecific eggplant population, segregating for resistance, was created from the cross between the susceptible MM738 and the resistant EG203 lines. The population of 123 doubled haploid lines was challenged with two strains belonging to phylotypes I (PSS4) and III (R3598), which both bypass the published EBWR9 BW-resistance quantitative trait locus (QTL). Ten and three QTLs of resistance to PSS4 and to R3598, respectively, were detected and mapped. All were strongly influenced by environmental conditions. The most stable QTLs were found on chromosomes 3 and 6. Given their estimated physical position, these newly detected QTLs are putatively syntenic with BW-resistance QTLs in tomato. In particular, the QTLs' position on chromosome 6 overlaps with that of the major broad-spectrum tomato resistance QTL Bwr-6. The present study is a first step towards understanding the complex polygenic system, which underlies the high level of BW resistance of the EG203 line.

Recurrent anaphylaxis in patient allergic to eggplant - a Lipid transfer protein (LTP) syndrome.

Eggplant allergy is rare and most of the previously described reactions were mild. In this case report, we present an interesting case of a 27-year-old male who experienced symptoms of anaphylaxis (shortness of breath, and swelling of the face, lips and tongue, which was followed by hypotension, tachycardia of 140/min and a sudden loss of consciousness) several minutes after eating a dish containing backed eggplant. Previously, the patient had experienced symptoms of allergy after eating different types of food, such as salad and chicken in spices. The symptoms were enhanced by co-factors. They were heterogeneous, ranging from oral symptoms to anaphylactic shock. During the diagnostic pathway, skin prick tests (SPTs) were positive to grass and cat. Prick by prick skin tests were positive for eggplant, both cooked and fresh. In ImmunoCap ISAC, IgE specific to rPhl p 1 (1.7 ISU-E), rCan f 5 (1,2 ISU-E), Fel d 1 (9.6 ISU-E ) and LTPs - nJug r 3 (0.5 ISU-E), rPru p 3 (0.6 ISU-E), rPla a 3 (1.3 ISU-E) were found. Based on the clinical pattern of the disease and the results of component resolved diagnosis, we suspect that this complex case of anaphylaxis may be gathered with LTP syndrome.

Genome-Enabled Phylogeographic Investigation of the Quarantine Pathogen Ralstonia solanacearum Race 3 Biovar 2 and Screening for Sources of Resistance Against Its Core Effectors.

Phylogeographic studies inform about routes of pathogen dissemination and are instrumental for improving import/export controls. Genomes of 17 isolates of the bacterial wilt and potato brown rot pathogen Ralstonia solanacearum race 3 biovar 2 (R3bv2), a Select Agent in the United States, were thus analyzed to get insight into the phylogeography of this pathogen. Thirteen of fourteen isolates from Europe, Africa, and Asia were found to belong to a single clonal lineage while isolates from South America were genetically diverse and tended to carry ancestral alleles at the analyzed genomic loci consistent with a South American origin of R3bv2. The R3bv2 isolates share a core repertoire of 31 type III-secreted effector genes representing excellent candidates to be targeted with resistance genes in breeding programs to develop durable disease resistance. Toward this goal, 27 R3bv2 effectors were tested in eggplant, tomato, pepper, tobacco, and lettuce for induction of a hypersensitive-like response indicative of recognition by cognate resistance receptors. Fifteen effectors, eight of them core effectors, triggered a response in one or more plant species. These genotypes may harbor resistance genes that could be identified and mapped, cloned, and expressed in tomato or potato, for which sources of genetic resistance to R3bv2 are extremely limited.

Effect of mixture of Trichoderma isolates on biochemical parameters in leaf of Macrophomina phaseolina infected brinjal.

A mixture of Trichoderma harzianum NBRI-1055 (Fx) and T. harzianum BHU-99 (Th) was evaluated for their efficiency to induce systemic resistance during three way interaction among brinjal-Trichoderma-Macrophomina phaseolina. Total phenol content (TPC), defence related enzymes Phenylalanine ammonia-lyase (PAL), Peroxidase (PO), Polyphenol oxidase (PPO) and PR proteins (PR-2 and PR-3) were recorded. Total phenolic content was recorded 12.82 times and 1.8 times higher in Trichoderma mixture treated-pathogen challenge (Fx-Th-Pth) treatment than in untreated healthy control and untreated pathogen challenged (Pth) plants respectively after 72 hr pathogen inoculation (hapi). Defence related enzymes PAL 4.54 times higher, 48hapi, PO, 3.96 times higher, 72hapi and PPO 8.1 times higher, 72hapi in Fx-Th-Pth treatment than untreated healthy control, and the PR- proteins such as PR-2, 2.15 times and PR-3, 2.16 times higher, 72hapi than untreated healthy control. The results showed that a mixture of Trichoderma (Fx+Th) performed better than single isolate.

Introgression of bacterial wilt resistance from eggplant to potato via protoplast fusion and genome components of the hybrids.

KEY MESSAGE: Bacterial wilt resistant somatic hybrids were obtained via protoplast fusion between potato and eggplant and three types of nuclear genomes were identified in the hybrids through GISH and SSR analysis. ABSTRACT: Cultivated potato (Solanum tuberosum L.) lacks resistance to bacterial wilt caused by Ralstonia solanacearum. Interspecific symmetric protoplast fusion was conducted to transfer bacterial wilt resistance from eggplant (S. melongena, 2n = 2x = 24) into dihaploid potato (2n = 2x = 24). In total, 34 somatic hybrids were obtained, and of these, 11 rooted and were tested for genome components and resistance to race 1 of R. solanacearum. The hybrids exhibited multiple ploidy levels and contained the dominant nuclear genome from the potato parent. Three types of nuclear genomes were identified in the hybrids through genomic in situ hybridization (GISH) and simple sequence repeat (SSR) analysis, including (1) the potato type of the tetraploids in which eggplant chromosomes could not be detected by GISH but their nuclear DNA was confirmed by SSR, (2) the biased type of the hexaploids in which the chromosome dosage was 2 potato:1 eggplant, and (3) the chromosome translocation type of the mixoploids and aneuploids that was characterized by various rates of translocations of nonhomologous chromosomes. Cytoplasmic genome analysis revealed that mitochondrial DNA of both parents coexisted and/or recombined in most of the hybrids. However, only potato chloroplast DNA was retained in the hybrids speculating a compatibility between cpDNA and nuclear genome of the cell. The pathogen inoculation assay suggested a successful transfer of bacterial wilt resistance from eggplant to the hybrids that provides potential resistance for potato breeding against bacterial wilt. The genome components characterized in present research may explain partially the inheritance behavior of the hybrids which is informative for potato improvement.

Chitosan and EDTA conjugated graphene oxide antinematodes in Eggplant: Toward improving plant immune response.

A new strategy regarding the fabrication of chitosan (CS) or ethylene diamine tetraacetic acid (EDTA) on graphene oxide (GO) was performed. The nematocidal potential against Meloidogyne incognita causing root-knot infection in eggplant was tested. The plant immune response was investigated through measuring the photosynthetic pigments, phenols and proline contents, oxidative stress, and antioxidant enzymes activity. Results indicating that, the treatment by pure GO recorded the most mortality percentages of M. incognita 2nd juveniles followed by GO-CS then GO-EDTA. In vivo greenhouse experiments reveals that, the most potent treatment in reducing nematodes was GO-CS which recorded 85.42%, 75.3%, 55.5%, 87.81%, and 81.32% in numbers of 2nd juveniles, galls, females, egg masses and the developmental stage, respectively. The highest chlorophyll a (104%), chlorophyll b (46%), total phenols (137.5%), and free proline (145.2%) were recorded in GO-CS. The highest malondialdehyde (MDA) value was achieved by GO-EDTA (7.22%), and hydrogen peroxide (H2O2) content by 47.51% after the treatment with pure GO. Treatment with GO-CS increased the activities of catalase (CAT) by 98.3%, peroxidase (POD) by 97.52%, polyphenol oxidase (PPO) by 113.8%, and superoxide dismutase (SOD) by 42.43%. The synthesized nanocomposites increases not only the nematocidal activity but also the plant systematic immune response.

Disease Classification in Eggplant Using Pre-trained VGG16 and MSVM.

Currently, the application of deep learning in crop disease classification is one of the active areas of research for which an image dataset is required. Eggplant (Solanum melongena) is one of the important crops, but it is susceptible to serious diseases which hinder its production. Surprisingly, so far no dataset is available for the diseases in this crop. The unavailability of the dataset for these diseases motivated the authors to create a standard dataset in laboratory and field conditions for five major diseases. Pre-trained Visual Geometry Group 16 (VGG16) architecture has been used and the images have been converted to other color spaces namely Hue Saturation Value (HSV), YCbCr and grayscale for evaluation. Results show that the dataset created with RGB and YCbCr images in field condition was promising with a classification accuracy of 99.4%. The dataset also has been evaluated with other popular architectures and compared. In addition, VGG16 has been used as feature extractor from 8th convolution layer and these features have been used for classifying diseases employing Multi-Class Support Vector Machine (MSVM). The analysis depicted an equivalent or in some cases produced better accuracy. Possible reasons for variation in interclass accuracy and future direction have been discussed.

Identification, cloning, and immunological studies on a major eggplant (Solanum melongena L.) allergen Sola m 1: A new member of profilin allergen family.

Eggplant or brinjal (Solanum melongena L.) is widely consumed worldwide and thought to trigger allergic reactions in sensitive individuals. So far, no molecular information is available on the allergy-eliciting components of eggplant. In this study, a 17 kDa profilin, Sola m 1, was identified from eggplant by employing an immunoproteomic approach. Based on MALDI-TOF/TOF derived sequences, the full-length cDNA of Sola m 1 was PCR amplified and then cloned. Recombinant (r) Sola m 1 was expressed in E. coli and then purified by metal affinity and gel filtration. rSola m 1 reacted with IgE-antibodies in the sera from all eggplant allergic patients. rSola m 1 also displayed allergenic activity by stimulating histamine release. rSola m 1 was monomeric, and the CD spectra revealed it to be folded with a mixture of α-helices and ß-strands. In the melting curve, rSola m 1 exhibited an irreversible denaturation where no refolding took place. Sola m 1 was found to share >80 % sequence identity with Bet v 2, which was further validated by confirming the presence of significant cross-reactivity with Bet v 2 in IgE-inhibition assay. IgE-cross reactivity was also observed between rSola m 1 and profilins from six other foods. In SGF assay, no rSola m 1-derived fragments exhibited IgE-reactivity after prolonged digestion suggesting the association of rSola m 1 with the oral allergy syndromes. Immunofluorescence localization revealed a high abundance of Sola m 1 allergen in eggplant seeds as compared to other edible parts. Taken together, Sola m 1 is the first major eggplant allergen reported in this study, which has the potential of being used as a candidate antigen in component-resolved diagnosis and immunotherapy.

Higher histamine sensitivity in non-atopic subjects by skin prick test may result in misdiagnosis of eggplant allergy.

Eggplant (aubergine; Solanum melongena L.), a member of the nightshade family, is widely consumed as a vegetable. A high incidence of allergic reactions to eggplant appears to be commonly experienced among Indians, presumably due to its high histamine content. Therefore, it appeared interesting to investigate the histamine content of different varieties of eggplant (green and purple round; green and purple slender long) using raw, cooked, and dialyzed extracts. A significant varietal difference in the histamine content of eggplant varieties was observed. Highest amount was present in the green round variety (2.41 mg/100 g fresh weight in raw and 2.07 mg/100 g in cooked extracts). The histamine content of other varieties (in mg/100 g raw) is: green slender long (1.80), purple slender long (1.35), and purple round (0.89). Histamine is stable to heat-processing, since only 11-14% loss was observed upon cooking. Skin prick test (SPT) on non-atopic subjects (without any history of eggplant allergy) using four varieties of raw and cooked eggplant extracts revealed that only subjects with a lower threshold for histamine produce positive results equivalent to that seen between 10-100 microg/mL histamine dihydrochloride. It can be concluded that the amount of histamine present in eggplant does not produce a positive SPT response in a majority of non-atopic subjects, and that a positive response in a few subjects are likely to be misdiagnosed as eggplant allergy.

A cross-sectional study on the prevalence of food allergy to eggplant (Solanum melongena L.) reveals female predominance.

BACKGROUND: Only a few case reports of allergy to eggplant (Solanum melongena) have been reported. A relatively large number of individuals appear to experience food-related symptoms to eggplant in India. OBJECTIVE: The major aims of this study are to assess the prevalence of food allergy to eggplant and analyse the age and gender distribution. METHODS: Seven hundred and forty-one subjects (age range: 5-60 years) randomly selected from rural and urban areas of Mysore city were analysed for the prevalence of eggplant allergy based on case history, skin prick test (SPT) with eggplant extracts and allergen-specific IgE. The age and gender distribution for the prevalence of eggplant allergy and its association with other atopic conditions were assessed. RESULTS: Sixty-eight (9.2%) subjects reported adverse reactions to ingestion of eggplant, of which 32 (4.3%) subjects had positive history/positive SPT and 36 (4.9%) had positive history/negative SPT. Sixteen (2.2%) subjects had negative history/positive SPT. Ten subjects (1.4%) experienced allergic symptoms in <2 h. Sensitization to eggplant by SPT was more in atopic (16.7%) compared with non-atopic subjects (3.8%). All the SPT-positive subjects (n=48) underwent evaluation for eggplant allergen-specific IgE, which was detected in 6 subjects (0.8%). Majority of the subjects sensitized to eggplant were in the age groups 16-45 years, and females were twice as likely to be sensitized as males. Female predominance (4 : 1) is more in the 16-30 year group. CONCLUSIONS: Many subjects experience adverse reactions to the ingestion of eggplant, possibly due to the pharmacologic action of histamine and other non-protein components, rather than to specific protein allergen(s). The prevalence of IgE-mediated eggplant allergy is estimated at approximately 0.8%, with higher rates of sensitization in females.

Allergy to eggplant (Solanum melongena) caused by a putative secondary metabolite.

We describe a case of allergy caused by ingestion of eggplant in an atopic subject. Symptoms included urticaria, itching of the throat, and hoarseness. Skin prick test (SPT) was positive with 4 varieties of eggplant; however, allergen-specific immunoglobulin E was not detected. SPT with fractions of green long eggplant extract obtained by dialysis and ultrafiltration suggested the allergen to be less than 10 kd. SPT following acetone precipitation of eggplant extract revealed that the allergen was present in the supernatant portion. Further analysis by size-exclusion chromatography of the 10 kd filtrate of eggplant extract on Sephadex G-25 followed by SPT of fractions revealed that the causative allergen was a low molecular weight nonprotein secondary metabolite of less than 1 kd. To our knowledge, this is the first report of allergy to the ingestion of eggplant in which a nonprotein secondary metabolite has been detected as an allergen.

The eggplant AG91-25 recognizes the Type III-secreted effector RipAX2 to trigger resistance to bacterial wilt (Ralstonia solanacearum species complex).

To deploy durable plant resistance, we must understand its underlying molecular mechanisms. Type III effectors (T3Es) and their recognition play a central role in the interaction between bacterial pathogens and crops. We demonstrate that the Ralstonia solanacearum species complex (RSSC) T3E ripAX2 triggers specific resistance in eggplant AG91-25, which carries the major resistance locus EBWR9. The eggplant accession AG91-25 is resistant to the wild-type R. pseudosolanacearum strain GMI1000, whereas a ripAX2 defective mutant of this strain can cause wilt. Notably, the addition of ripAX2 from GMI1000 to PSS4 suppresses wilt development, demonstrating that RipAX2 is an elicitor of AG91-25 resistance. RipAX2 has been shown previously to induce effector-triggered immunity (ETI) in the wild relative eggplant Solanum torvum, and its putative zinc (Zn)-binding motif (HELIH) is critical for ETI. We show that, in our model, the HELIH motif is not necessary for ETI on AG91-25 eggplant. The ripAX2 gene was present in 68.1% of 91 screened RSSC strains, but in only 31.1% of a 74-genome collection comprising R. solanacearum and R. syzygii strains. Overall, it is preferentially associated with R. pseudosolanacearum phylotype I. RipAX2GMI1000 appears to be the dominant allele, prevalent in both R. pseudosolanacearum and R. solanacearum, suggesting that the deployment of AG91-25 resistance could control efficiently bacterial wilt in the Asian, African and American tropics. This study advances the understanding of the interaction between RipAX2 and the resistance genes at the EBWR9 locus, and paves the way for both functional genetics and evolutionary analyses.

Overexpression of the Eggplant (Solanum melongena) NAC Family Transcription Factor SmNAC Suppresses Resistance to Bacterial Wilt.

Bacterial wilt (BW) is a serious disease that affects eggplant (Solanum melongena) production. Although resistance to this disease has been reported, the underlying mechanism is unknown. In this study, we identified a NAC family transcription factor (SmNAC) from eggplant and characterized its expression, its localization at the tissue and subcellular levels, and its role in BW resistance. To this end, transgenic eggplant lines were generated in which the expression of SmNAC was constitutively up regulated or suppressed using RNAi. The results indicated that overexpression of SmNAC decreases resistance to BW. Moreover, SmNAC overexpression resulted in the reduced accumulation of the plant immune signaling molecule salicylic acid (SA) and reduced expression of ICS1 (a gene that encode isochorismate synthase 1, which is involved in SA biosynthesis). We propose that reduced SA content results in increased bacterial wilt susceptibility in the transgenic lines. Our results provide important new insights into the regulatory mechanisms of bacterial wilt resistance in eggplant.

Latex-vegetable syndrome due to custard apple and aubergine: new variations of the hevein symphony.

An increasing number of vegetables with crossreactions to latex are being described in patients with latex-vegetable syndrome. We present two of these vegetables, custard apple linked in two previous cases with latex sensitisation, and aubergine, that had not been described up to now in patients with latex sensitisation. The diagnosis of both cases was based on the clinical history, positive skin prick test (SPT) and specific IgE to the offending vegetables, as well as to positive SPT and specific IgE levels to latex and the major fruits involved in the latex-fruit syndrome (avocado, banana, and chestnut). Further, crude extracts from latex, custard apple and aubergine, as well as the purified allergens Hev b 6.02 and Prs a 1 were used in in vitro and in vivo assays: IgE immunodetection, histamine release (HRT) and basophil activation (BAT) tests and skin prick tests. In case 1, both purified Hev b 6.02 and Prs a 1 induced positive responses in skin prick tests, high levels of basophil activation and histamine release. Specific IgE immunodetection uncovered a reactive band of 45 kd in the crude custard apple extract, which was also recognized by anti-chitinase monospecific antibodies. The serum from patient 1 also detected Prs a 1 in immunodetection. Hev b 6.02 produced positive skin responses and showed high biological activity in HRT and BAT in the case of patient 2. However, Prs a 1 was reactive neither in SPT nor in IgE immunodetection. In fact, no band was detected using the serum of patient 2 in avocado or aubergine extracts. By contrast, Prs a 1 reached high values of basophil activation and over 10% of histamine release in case 2.

IgE response to two new allergen proteins of Solanum melongena L. (eggplant).

A number of allergens from eggplant (Solanum melongena L.) have been previously identified. In this study, we could detect IgE reactivity of two allergic subjects' sera towards two protein bands of molecular mass of about 35 and 15 kDa. As IgE were reactive to both raw and cooked eggplant extracts, a heat-stable nature of these novel allergens is apparent.

Eggplant and related species are promising genetic resources to dissect the plant immune response to Pseudomonas syringae and Xanthomonas euvesicatoria and to identify new resistance determinants.

The apparent lack of durability of many resistance (R) genes highlights the need for the constant identification of new genetic sources of resistance for the breeding of new disease-resistant crop cultivars. To this end, we screened a collection of accessions of eggplant and close relatives for resistance against Pseudomonas syringae pv. tomato (Pto) and Xanthomonas euvesicatoria (Xeu), foliar plant pathogens of many solanaceous crops. Both pathogens caused substantial disease on most genotypes of eggplant and its relatives. Promisingly, however, some of the genotypes were fully or partially resistant to either of the pathogens, suggesting the presence of effective resistance determinants in these genotypes. Segregation of resistance to the growth of Xeu following infiltration in F2 progeny from a cross of a resistant and susceptible genotype suggests that resistance to Xeu is inherited as a multigenic trait. With regard to Pto, a mutant strain lacking all 28 functional type III secreted effectors, and a Pseudomonas fluorescens strain expressing a P. syringae type III secretion system (T3SS), both elicit a strong cell death response on most eggplant lines. Several genotypes thus appear to harbour a mechanism for the direct recognition of a component of the T3SS. Therefore, eggplant and its close relatives are promising resources to unravel novel aspects of plant immunity and to identify new candidate R genes that could be employed in other Solanaceae in which Xeu and Pto cause agriculturally relevant diseases.