Phenylalanine increases chrysanthemum flower immunity against Botrytis cinerea attack.

Flowers are the most vulnerable plant organ to infection by the necrotrophic fungus Botrytis cinerea. Here we show that pre-treatment of chrysanthemum (Chrysanthemum morifolium) flowers with phenylalanine (Phe) significantly reduces their susceptibility to B. cinerea. To comprehend how Phe treatment induces resistance, we monitored the dynamics of metabolites (by GC/LC-MS) and transcriptomes (by RNAseq) in flowers after Phe treatment and B. cinerea infection. Phe treatment resulted in accumulation of 3-phenyllactate and benzaldehyde, and in particular induced the expression of genes related to Ca2+ signaling and receptor kinases, implicating an induction of the defense response. Interestingly, the main effects of Phe treatment were observed in flowers exposed to B. cinerea infection, stabilizing the global fluctuations in the levels of metabolites and transcripts while reducing susceptibility to the fungus. We suggest that Phe-induced resistance is associated to cell priming, enabling rapid and targeted reprogramming of cellular defense responses to resist disease development. After Phe pre-treatment, the levels of the anti-fungal volatiles phenylacetaldehyde and eugenol were maintained and the level of coniferin, a plausible monolignol precursor in cell wall lignification, was strongly increased. In addition, Phe pre-treatment reduced ROS generation, prevented ethylene emission, and caused changes in the expression of a minor number of genes related to cell wall biogenesis, encoding the RLK THESEUS1, or involved in Ca2+ and hormonal signaling processes. Our findings point to Phe pre-treatment as a potential orchestrator of a broad-spectrum defense response which may not only provide an ecologically friendly pest control strategy but also offers a promising way of priming plants to induce defense responses against B. cinerea.

Protein contact dermatitis to chrysanthemum

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Occupational allergy to flowers: immunoblot analysis of allergens in freesia, gerbera and chrysanthemum pollen.

High exposure to pollen from ornamental flowers can induce an IgE-mediated occupational allergy in florists and horticulture workers. We investigated IgE-binding antigens in chrysanthemum, freesia and gerbera pollen by immunoblot analysis and analysed the cross-reactivity of these pollen with birch, grass and mugwort pollen. In immunoblots with chrysanthemum pollen, major IgE-binding structures were seen with a molecular weight (MW) of approximately 25, 45 and 65 kD. In the immunoblots with freesia pollen, IgE from freesia pollen was directed against two proteins with an MW of approximately 15 kD. Most sera showed IgE binding to an approximately 15 kD band in gerbera pollen; with some sera additional bands were seen in the range of 30-50 kD. IgE binding to chrysanthemum pollen was inhibited by mugwort pollen only, whereas IgE binding to freesia pollen was suppressed by birch, grass and mugwort pollen. The inhibitory activity of birch and grass pollen extract on IgE binding to gerbera pollen extract was serum dependent and ranged from no inhibition to complete inhibition. Occupational exposure to many different flowers induced IgE against all three types of pollen. Exposure in greenhouses to gerbera flowers elicited mainly IgE against gerbera pollen. Mugwort pollen extract inhibited IgE binding to pollen from all three flowers.

Differential allergenicity of mature and immature pollen grains in Shasta daisy (Chrysanthemum maximum Ramond).

Weed pollen grains belonging to the Asteraceae family contain a variety of allergens inducing type I and IV allergies in susceptible people. The aim of this research was to compare the allergenic properties of immature and mature Shasta daisy pollen grains (Chrysanthemum maximum Ramond) to define the potential role of the maturation process on the allergenicity of Asteraceae pollen grains. The immature (IP) and mature pollen (MP) grains were first studied by optical and scanning electron microscopand their protein contents were quantitatively and qualitatively analyzed. Pollen extracts were finally used to sensitize guinea pigs in order to obtain IP and MP specific antibodies. Nasal provocation tests using IP and MP crude extracts were also performed on pre-sensitized guinea pigs. The MP extract induced IgE and eosinophilia in blood and positive skin tests in sensitized guinea pigs. Moreover, high number of eosinophils was found in the nasal mucosa of MP sensitized guinea pigs. SDS-PAGE analysis of the IP and MP protein content showed seven and five apparent bands ranging from 7 to 66kDa respectively. According to immunoblot analysis, MP extract contained a single allergen of 66kDa. The overall results showed developmental processes of Shasta daisy pollen grains towards both morphological and molecular changes increasing their allergenic potency.

Lower incidence of sesquiterpene lactone sensitivity in a population in Asia versus a population in Europe: an effect of chrysanthemum tea?

Sesquiterpene lactones (SLs) (Fig. 1) are an important cause of allergic plant contact dermatitis but are uncommon in the Far East. They belong to the Compositae family of plants. Sensitivity to SL may be airborne or via the topical route [topical herbal remedies, cosmetic products, and in many occupations such as gardeners and florists].

Susceptibility of gerbera and chrysanthemum varieties (Gerbera jamesoni and Chrysanthemum morifolium) to Fusarium oxysporum f.sp. chrysanthemi.

In 2002, gerbera plants (cv Kaliki) were observed exhibiting symptoms of a wilt in a soilless cultivation at Albenga area (Northern Italy). A similar wilt was also observed in the Sanremo area (Northern Italy) on cv Red Bull, Anedin and Gud finger grown in soil. The same observations were carried out in 2004 in SW Spain where gerbera plants showing wilt symptoms were observed in soilless crops. In all cases, the planting material originated from the Netherlands. Recently on the base of experimental trials F. oxysporum f. sp. chrysanthemi was recognized as the causal agent of wilts of gerbera both in Italy and in Spain. The aim of this experimental work was the evaluation of the resistance/susceptibility of available cultivars of chrysanthemum and gerbera to the Fusarium wilt. The pathogenicity of two isolates of Fusarium chrysanthemi obtained from infected gerbera (Gerbera jamesonii) and chrysanthemum (Chrysanthemum morifolium) plants was tested on several varieties both of gerbera and chrysanthemum in 2004-2006. In 2004 and 2005 respectively 54 and 30 cultivars of chrysanthemum and 57 and 55 of gerbera were tested, while in 2006 only 53 cultivars of gerbera were tested. The results showed that respectively in 2004 and 2005 67 and 33 % of chrysanthemum cultivars were highly resistant to F. chrysanthemi obtained from chrysanthemum while 57 and 53 % were highly resistant to strain isolated from gerbera. In 2004, 2005 and 2006 47, 65 and 75 % of gerbera cultivars were highly resistant to F. chrysanthemi obtained from chrysanthemum and 48, 56 and 72 % were highly resistant to the strain isolated from gerbera.