Is the nectar redox cycle a floral defense against microbial attack?

Carter, Clay J.; Thornburg, Robert W.

doi:10.1016/j.tplants.2004.05.008

Cited by 170 publications

(200 citation statements)

References 48 publications

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“…The amino acid sequence and functions of the so-called Nectarin proteins were determined in the floral nectar of the ornamental tobacco hybrid LxS8 (Nicotiana langsdorffii × Nicotiana sanderae var. LxS8) [19][20][21]53]. These proteins were shown to be enzymes with antimicrobial activity playing a key role in protecting the gynoecium against microorganisms.…”

Section: Acta Biologica Hungarica 66 2015mentioning

confidence: 99%

“…Other nectar protein bands of Nicotiana species investigated in the present study also correspond to Nectarin proteins. The more powerful band slightly below the 66.2 kDa marker in both N. alata and N. rustica is the Nectarin IV (NEC4) protein with 60 kDa molecular weight and poligalacturonase inhibitor function [53] and it is a tandem of the Nectarin V (NEC5) protein with glucose oxidase activity and a molecular weight of 61-65 kDa, described by Carter [21]. The protein band faintly visible in N. rustica between 45 and 35 kDa can be considered to be the Nectarin III (NEC3) protein with bifunctional monodehydroascorbate reductase and carbonic anhydrase activities and a molecular weight of 40 kDa, as described by Carter and Thornburg [20].…”

Section: Alkaloid Content Of the Floral Nectarmentioning

confidence: 99%

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Protein and alkaloid patterns of the floral nectar in some solanaceous species

Kerchner¹,

Darók²,

Bacskay³

et al. 2015

Acta Biologica Hungarica

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The family Solanaceae includes several melliferous plants, which tend to produce copious amounts of nectar. Floral nectar is a chemically complex aqueous solution, dominated by sugars, but minor components such as amino acids, proteins, flavonoids and alkaloids are present as well. This study aimed at analysing the protein and alkaloid profile of the nectar in seven solanaceous species. Proteins were examined with SDS-PAGE and alkaloids were analyzed with HPLC. The investigation of protein profile revealed significant differences in nectar-protein patterns not only between different plant genera, but also between the three Nicotiana species investigated. SDS-PAGE suggested the presence of several Nectarin proteins with antimicrobial activity in Nicotiana species. The nectar of all tobacco species contained the alkaloid nicotine, N. tabacum having the highest nicotine content. The nectar of Brugmansia suaveolens, Datura stramonium, Hyoscyamus niger and Lycium barbarum contained scopolamine, the highest content of which was measured in B. suaveolens. The alkaloid concentrations in the nectars of most solanaceous species investigated can cause deterrence in honeybees, and the nectar of N. rustica and N. tabacum can be considered toxic for honeybees.

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Section: Acta Biologica Hungarica 66 2015mentioning

confidence: 99%

Section: Alkaloid Content Of the Floral Nectarmentioning

confidence: 99%

Protein and alkaloid patterns of the floral nectar in some solanaceous species

Kerchner¹,

Darók²,

Bacskay³

et al. 2015

Acta Biologica Hungarica

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“…Another research revealed that GhPrx37, a floral-specific peroxidases of G. hirsutum was predominantly expressed during pollen development and it could be important for the correct development of male reproductive organs, because of its putative role in defence against stress [12]. In addition, high level of H 2 O 2 , produced by a superoxide dismutase were detected in nectar, with the aim of protecting it from microbial infections [51]. In the same way the abundant presence of H 2 O 2 in the stigmas and the almost total absence of pathogen attack on stigmas could improve the hypothesis about a possible interaction between stigma-specific peroxidases and H 2 O 2 with a defence role [6].…”

Section: Discussionmentioning

confidence: 99%

Isolation of a gene encoding for a class III peroxidase in female flower of Corylus avellana L.

et al. 2012

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Hazelnut is a monoecius species characterized by mid-winter blooming and sporophytic incompatibility. The molecular mechanisms at the basis of the female flower development and of the pollen-stigma interaction are little known, although pollination in this species is a critical factor to ensure good yield. Differential Display technique was used to study genes expressed during the female flower development, comparing styles before emergence from the bud and styles at full bloom. The full-length cDNA clone, designated CavPrx (Corylus avellana peroxidase) and isolated in mature styles, was characterized as a sequence encoding for a 330 amino acids protein, containing all the conserved features of class III peroxidases. CavPrx resulted expressed only in styles, with a peak in mature styles pollinated with compatible pollen. Class III peroxidases are expressed in several different plant tissue types and are involved in a broad spectrum of physiological processes. Until now, four peroxidases expressed in the stigma were identified in Arabidopsis thaliana and Senecio squalidus: they were assumed to be possibly involved in pollen-pistil interaction, pollen tube penetration/growth and/or in defence against pathogens. CavPrx is the first gene for a floral peroxidase isolated in hazelnut and its expression pattern suggests a possible role in the pollination process.

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“…Antimicrobial compounds in the nectar have been hypothesized to function in the attraction and reward of pollinators, by hindering microbial degradation of nectar sugars (Adler 2000); or to protect the floral reproductive tract from contamination by microbes brought to the flower by nonsterile pollinators or by airborne means (Carter and Thornburg 2004). Sasu et al (2010b) demonstrated recently that nectar inhibited the growth of E. tracheiphila, the causative agent of wilt disease.…”

Section: Nectar Secretion and Compositionmentioning

confidence: 99%

“…Although hydrogen peroxide produced from the nectar redox cycle was shown to be a major factor contributing to inhibition of most microbial growth in floral nectar (Carter and Thornburg 2004); E. amylovora was reported to grow well in nectar, being resistant to the H 2 O 2 concentrations found in nectar (Carter et al 2007). The pathogen's tolerance to oxidative stress may contribute to the unique etiology of E. amylovora.…”

Section: Nectar Secretion and Compositionmentioning

confidence: 99%

Floral traits affecting fire blight infection and management

Farkas

Mihalik

Dorgai³

et al. 2011

Trees

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Erwinia amylovora, the causative agent of fire blight, colonizes primarily the flowers of the sub-family Maloideae. Commercially important fruit tree species such as apple (Malus domestica) and pear (Pyrus communis) are also affected by the disease. Epiphytic bacterial populations develop on the stigma, from where the pathogen colonizes the hypanthium, aided by moisture. Under favorable conditions, nectar provides a rich medium for growth, which allows bacterial invasion of tissues through the stomata of the nectary. The paper reviews various floral traits that may play a role in the onset and progression of the infection. Flower age, stigma morphology and longevity, the size of epiphytic bacterial population, morphology of the hypanthium, anatomy of the nectary, dynamics of nectar secretion, as well as the volume, concentration and composition of the nectar are discussed in detail, comparing traits of susceptible versus tolerant apple and pear cultivars. Management programs, aiming at the suppression of E. amylovora on floral parts by antibiotics, chemical compounds, natural substances or biological control agents, are also discussed.

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Is the nectar redox cycle a floral defense against microbial attack?

Cited by 170 publications

References 48 publications

Protein and alkaloid patterns of the floral nectar in some solanaceous species

Protein and alkaloid patterns of the floral nectar in some solanaceous species

Isolation of a gene encoding for a class III peroxidase in female flower of Corylus avellana L.

Floral traits affecting fire blight infection and management

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