The Ficus erecta genome aids Ceratocystis canker resistance breeding in common fig (F. carica).

Ficus erecta, a wild relative of the common fig (F. carica), is a donor of Ceratocystis canker resistance in fig breeding programmes. Interspecific hybridization followed by recurrent backcrossing is an effective method to transfer the resistance trait from wild to cultivated fig. However, this process is time consuming and labour intensive for trees, especially for gynodioecious plants such as fig. In this study, genome resources were developed for F. erecta to facilitate fig breeding programmes. The genome sequence of F. erecta was determined using single-molecule real-time sequencing technology. The resultant assembly spanned 331.6 Mb with 538 contigs and an N50 length of 1.9 Mb, from which 51 806 high-confidence genes were predicted. Pseudomolecule sequences corresponding to the chromosomes of F. erecta were established with a genetic map based on single nucleotide polymorphisms from double-digest restriction-site-associated DNA sequencing. Subsequent linkage analysis and whole-genome resequencing identified a candidate gene for the Ceratocystis canker resistance trait. Genome-wide genotyping analysis enabled the selection of female lines that possessed resistance and effective elimination of the donor genome from the progeny. The genome resources provided in this study will accelerate and enhance disease-resistance breeding programmes in fig.

Defence mechanisms of Ficus: pyramiding strategies to cope with pests and pathogens.

Ficus species have adapted to diverse environments and pests by developing physical or chemical protection strategies. Physical defences are based on the accumulation of minerals such as calcium oxalate crystals, amorphous calcium carbonates and silica that lead to tougher plants. Additional cellular structures such as non-glandular trichomes or laticifer cells make the leaves rougher or sticky upon injury. Ficus have also established structures that are able to produce specialized metabolites (alkaloids, terpenoids, and phenolics) or proteins (proteases, protease inhibitors, oxidases, and chitinases) that are toxic to predators. All these defence mechanisms are distributed throughout the plant and can differ depending on the genotype, the stage of development or the environment. In this review, we present an overview of these strategies and discuss how these complementary mechanisms enable effective and flexible adaptation to numerous hostile environments.

Comparative multi-omics analysis reveals diverse latex-based defense strategies against pests among latex-producing organs of the fig tree (Ficus carica).

MAIN CONCLUSION: Latexes in immature fruit, young petioles and lignified trunks of fig trees protect the plant using toxic proteins and metabolites in various organ-dependent ways. Latexes from plants contain high amounts of toxic proteins and metabolites, which attack microbes and herbivores after exudation at pest-induced wound sites. The protein and metabolite constituents of latexes are highly variable, depending on the plant species and organ. To determine the diversity of latex-based defense strategies in fig tree (Ficus carica) organs, we conducted comparative proteomic, transcriptomic and metabolomic analyses on latexes isolated from immature fruit, young petioles and lignified trunks of F. carica after constructing a unigene sequence library using RNA-seq data. Trypsin inhibitors were the most abundant proteins in petiole latex, while cysteine proteases ("ficins") were the most abundant in immature fruit and trunk latexes. Galloylglycerol, a possible defense-related metabolite, appeared to be highly accumulated in all three latexes. The expression levels of pathogenesis-related proteins were highest in the latex of trunk, suggesting that this latex had adapted a defensive role against microbe attacks. Although young petioles and immature fruit are both unlignified soft organs, and potential food for herbivorous insects, unigenes for the sesquiterpenoid pathway, which likely produces defense-associated volatiles, and the phenylpropanoid pathway, which produces toxic furanocoumarins, were expressed less in immature fruit latex. This difference may indicate that while petioles and fruit protect the plant from attack by herbivores, the fruit must also attract insect pollinators at younger stages and animals after ripening. We also suggest possible candidate transcription factors and signal transduction proteins that are involved in the differential expression of the unigenes.

An alternative inhibition method for determining cross-reactive allergens.

BACKGROUND: Inhibition assays are an useful tool to identify the allergen of primary sensitization of cross-reactive allergens. Classical ELISA-based inhibition assays are limited by both the availability of commercial standardized allergen extracts and the experience and knowledge needed for making home-made extracts. Moreover the direct comparison of the inhibition ELISAs outcomes between different laboratories is difficult because of different sources of used allergen extracts and a number of methodological variations. Therefore, we propose a novel ImmunoCap (Phadia, Thermofisher Scientific) based immunoinhibition method with the use of commercially available Caps as the allergen source. METHODS: The novel ImmunoCap based immunoinhibition method was developed and tested with sera from patients with a well-known cross-reactive sensitization for fig (Ficus carica) and ficus (Ficus benjamina). Results were compared with a classically applied inhibition method, i.e. addition of homemade allergen extract to patient serum. RESULTS: The amount of allergens (fig and ficus extracts) needed to reach a similar degree of inhibition was comparable for both inhibition methods. CONCLUSIONS: The ImmunoCap based inhibition assay, in addition to classical inhibition methods, is a valuable tool as the ImmunoCap analyzer and commercial allergens (Caps) are more widely available which makes the outcomes of inhibition tests comparable between different laboratories. Furthermore, in the ImmunoCap inhibition method the same protein source is used for both the inhibition of sIgE and sIgE measurement, which might be even more relevant when multiple cross-reactive allergens are tested.

Identification of Bet v 1-related allergens in fig and other Moraceae fruits.

BACKGROUND: Allergy to fig fruit (Ficus carica) has been described in patients allergic to Ficus benjamina or rubber latex but may occur also in pollen-allergic patients. OBJECTIVE: To study the potential cross-reactivity between fig and taxonomically related fruits with the major birch pollen allergen Bet v 1. METHODS: One hundred and eighty-eight patients with or without birch pollen allergy were prick-to-prick tested with fig (F. carica), mulberry (Morus alba), jackfruit (Artocarpus heterophyllus; all family Moraceae) and other pollen-associated foods. Moraceae fruit extracts were separated by SDS-PAGE and tested with patient sera and polyclonal antisera against Mal d 1. Western blot inhibition was performed with Moraceae fruit extracts, birch pollen and recombinant Bet v 1. Putative Bet v 1 homologs in Moraceae fruits were analysed by liquid chromatography-ion trap mass spectrometry. RESULTS: Among 85 patients with isolated birch pollen allergy, 78% had a positive skin test to fresh fig, 10% to dried fig, 91% to mulberry, 91% to jackfruit, 77% to Rosaceae fruits and 83% to hazelnut. Sixty-six per cent of birch pollen-allergic patients positive for fig, reported symptoms after consumption of fresh figs, whereas dried figs were mostly well tolerated. In 60 patients with isolated Ficus benjamina sensitization, the reactivity rates to the same foods were 83-40-0-0-0-0%. None of 32 mugwort pollen-allergic patients reacted to Moraceae fruits. Rabbit anti-Mal d 1 and patient sera reacted to a 17 kDa band in all Moraceae extracts. IgE binding to these proteins was completely inhibited by birch pollen and rBet v 1. Mass spectrometry identified several peptides from the 17 kDa fig, mulberry and jackfruit allergen with respectively 60%, 56% and 76% homology to Bet v 1. CONCLUSION: Fig and other Moraceae fruits contain allergens homologous to Bet v 1 and represent clinically relevant birch pollen-associated foods.

Allergy to Ficus benjamina.

The clinical history of 16 patients found to have specific IgE antibodies against Ficus benjamina was analyzed in terms of allergic symptoms, clinical and biological cross-sensitisation to other allergens and compared to the data found in the literature. Two different groups of patients were studied. Group A consisted of 13 patients who became sensitised through contact with ficus plants and experienced symptoms upon exposure. Their main symptoms where conjunctivitis, rhinitis, asthma, eyelid oedema or urticaria. Of these patients 11 had other atopic manifestations. Two persons had no other allergy. 10 patients experienced symptoms at home, 2 at the working place and 1 while being in a restaurant. One patient had a crossreactive food allergy to figs. Group B consisted of 3 highly atopic patients who had also a sensitization both to latex (Hevea brasiliensis) and to Ficus benjamina. They had no clinical history of allergic reactions provoked by ficus plants.

High incidence of sensitization to ornamental plants in allergic rhinitis.

BACKGROUND: A few indoor plants have been described as potential allergens, in single case reports of allergic rhinitis. There is no data evaluating the prevalence of allergic sensitization to these plants. AIM: The relationship between owning indoor ornamental plants with the risk to be sensitized has been evaluated in atopic rhinitis. METHODS: A group of 59 patients with allergic rhinitis were submitted to skin prick tests (SPT) using both the leafs of their own plant and commercial extracts of the most frequent airborne allergens. A control group of 15 healthy subjects was tested with the same allergens. RESULTS: While no subject from the control group developed a significant SPT to any of the tested plants, 78% of allergic rhinitis had positive SPT to at least one plant, the most frequent sensitization being Ficus benjamina, yucca, ivy and palm tree. CONCLUSION: In allergic rhinitis, indoor plants should be considered as potential allergens.

[Allergic contact urticaria caused by a chameleon. Expression of sensitization to Ficus benjamina]. / Allergische Kontakturtikaria durch ein Chamäleon. Ausdruck einer Sensibilisierung gegen Ficus benjamina.

A 31-year-old man presented with a long history of rhinoconjunctivitis and sneezing that lasted from March to May. The man kept a chameleon (Chamaeleo calyptratus) as a pet and reported about recurrent urticarial lesions, erythema, and itch after skin contact with the animal. The reactions started within a few minutes and were restricted specifically to the contact sites with the animal's claws. No comparable reactions occurred in other subjects. Allergy testing confirmed allergy to hazel, alder, birch, and ash pollen, and additionally revealed sensitization to house dust mite, cat, and Ficus benjamina. Apparently the contact dermatitis originated from passive transfer of Ficus benjamina allergens to the patient's skin by the reptile which habitually climbed on a big Ficus benjamina tree in the patient's home, thereby contaminating its claws with the plant's allergenic milky sap. Careful examination revealed strong perforation of many leaves by the pointed claws. The patient denied respiratory symptoms from Ficus benjamina and intolerance of Ficus-associated fruits.

Fig and mulberry cross-allergy.

BACKGROUND: Hypersensitivity reactions to ingestion of figs (Ficus carica) and mulberries (Morus nigra and Morus alba) are considered uncommon and have never been reported as occurring in the same patient. OBJECTIVE: To determine whether hypersensitivity to figs and mulberries can induce cross-allergy. METHODS: We describe 3 cases of associated fig and mulberry allergy in 3 patients with multiple sensitizations to food allergens (mostly fruit) and airborne allergens. The presence of specific IgE was investigated by skin prick tests and radioallergosorbent tests. RESULTS: The 3 patients had a convincing clinical history of food allergy caused by eating fresh figs, and in all 3 cases clinical and/or laboratory evidence of sensitization to mulberries was also collected. CONCLUSIONS: We reason that Ficus and Morus are closely related genera of the Moraceae family and speculate that hypersensitivity to figs and mulberries might be associated as the result of allergen cross-reactivity rather than mere coincidence.

Oral allergy syndrome to fig.

BACKGROUND: The few cases of food allergy to fig reported to date, whose main manifestations were anaphylactic reactions, have been related to a cross-sensitisation to weeping fig (Ficus benjamina) or to the 'latex-fruit syndrome'. Here we report on two cases of the oral allergy syndrome (OAS) to fig in patients whose main allergic manifestations were related to sensitisation to grass and birch pollens. METHODS: The patients were characterised by clinical history, skin prick tests (SPT) with commercial and in-house extracts, prick-by-prick test, specific IgE measurements and challenge tests. PBS-soluble and insoluble extracts of both fig skin and pulp were examined for the presence of potential allergens by IgE immunoblotting. RESULTS: Both patients showed OAS followed by respiratory symptoms when challenged with fig. They were negative in both specific IgE detection and SPT with commercial extracts of fig and many other plant materials, including F. benjamina and Hevea Brasiliensis, while grass and birch pollens gave positive results. Prick-by-prick tests and SPT with in-house extracts indicated that the fig skin had a much higher allergenicity than the pulp. Despite negative IgE detection by the CAP assay, immunoblotting experiments showed that potential fig allergens were PBS-soluble and present only in the skin of the fruit. CONCLUSIONS: OAS to fig followed by respiratory symptoms can be present in patients not sensitised to weeping fig or having the latex-fruit syndrome. Different parts of the fig can have different allergenicities, the most important allergens being proteins related to the skin of the fruit. Improved commercial fig extracts to be used for the diagnosis of this type of allergy have to be developed.

[Anaphylactic reaction to Ficus benjamina (weeping fig)]. / Anaphylaktische Reaktion durch Ficus benjamina (Birkenfeige).

Ficus benjamina (weeping fig) is a widespread indoor ornamental plant. Allergens of Ficus benjamina are a well-known cause of IgE-mediated respiratory diseases. We treated a 32-year-old female who for 10 years had suffered from perennial rhinoconjunctivitis. When dusting her 2 meter high Ficus benjamina, she developed an anaphylactic reaction which resolved without sequelae. Skin prick testing revealed a strong immediate type reaction to a Ficus extract, the serum concentration of specific IgE-antibodies to Ficus was > 100 kU/I (CAP class 6). In view of these strong test reactions and the conclusive history, no challenge tests with Ficus allergens were performed. After removal of the Ficus plants which she had owned for 17 years and after thorough cleaning of her dwelling, the patient's symptoms of perennial rhinoconjunctivitis stopped. The patient also was sensitized to, but not allergic to natural rubber latex, which occurs frequently in Ficus allergy and probably is due to cross reactivity to allergens from both sources. As Ficus benjamina is an important source of indoor allergens, it should not be used in dwellings or work places.