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Chemical diversity and defence metabolism: how plants cope with pathogens and ozone pollution.

Iriti M, Faoro F - Int J Mol Sci (2009)

Bottom Line: In plants, antibiotic compounds can be both preformed (phytoanticipins) and inducible (phytoalexins), the former including saponins, cyanogenic glycosides and glucosinolates.In some cases, the plant defence responses against pathogens and environmental pollutants may overlap, leading to the unspecific synthesis of similar molecules, such as phenylpropanoids.Finally, the synthesis of ethylene and polyamines can be regulated by ozone at level of S-adenosylmethionine (SAM), the biosynthetic precursor of both classes of hormones, which can, therefore, mutually inhibit their own biosynthesis with consequence on plant phenotype.

View Article: PubMed Central - PubMed

Affiliation: Università degli Studi di Milano, Dipartimento di Produzione Vegetale, Milano, Italy. marcello.iriti@unimi.it <marcello.iriti@unimi.it>

ABSTRACT
Chemical defences represent a main trait of the plant innate immune system. Besides regulating the relationship between plants and their ecosystems, phytochemicals are involved both in resistance against pathogens and in tolerance towards abiotic stresses, such as atmospheric pollution. Plant defence metabolites arise from the main secondary metabolic routes, the phenylpropanoid, the isoprenoid and the alkaloid pathways. In plants, antibiotic compounds can be both preformed (phytoanticipins) and inducible (phytoalexins), the former including saponins, cyanogenic glycosides and glucosinolates. Chronic exposure to tropospheric ozone (O(3)) stimulates the carbon fluxes from the primary to the secondary metabolic pathways to a great extent, inducing a shift of the available resources in favour of the synthesis of secondary products. In some cases, the plant defence responses against pathogens and environmental pollutants may overlap, leading to the unspecific synthesis of similar molecules, such as phenylpropanoids. Exposure to ozone can also modify the pattern of biogenic volatile organic compounds (BVOC), emitted from plant in response to herbivore feeding, thus altering the tritrophic interaction among plant, phytophagy and their natural enemies. Finally, the synthesis of ethylene and polyamines can be regulated by ozone at level of S-adenosylmethionine (SAM), the biosynthetic precursor of both classes of hormones, which can, therefore, mutually inhibit their own biosynthesis with consequence on plant phenotype.

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Influence of different stresses on plant metabolism. The activation of induced resistance leads to the accumulation of numerous defence compounds that may unbalance the equilibrium between primary and secondary metabolism, thus resulting in fitness costs for the plant. On the other hand, the synthesis of secondary metabolites due to a stress may protect plant from other different stresses.
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f5-ijms-10-03371: Influence of different stresses on plant metabolism. The activation of induced resistance leads to the accumulation of numerous defence compounds that may unbalance the equilibrium between primary and secondary metabolism, thus resulting in fitness costs for the plant. On the other hand, the synthesis of secondary metabolites due to a stress may protect plant from other different stresses.

Mentions: Finally, to the other side of the coin, an excessive production of secondary metabolites may be detrimental for the plant’s fitness (Figure 5), in terms of allocation costs and autotoxicity [152,153], though it may be favourable, at least in food plants, which could provide foodstuffs and beverages enriched of bioactive phytochemicals [154].


Chemical diversity and defence metabolism: how plants cope with pathogens and ozone pollution.

Iriti M, Faoro F - Int J Mol Sci (2009)

Influence of different stresses on plant metabolism. The activation of induced resistance leads to the accumulation of numerous defence compounds that may unbalance the equilibrium between primary and secondary metabolism, thus resulting in fitness costs for the plant. On the other hand, the synthesis of secondary metabolites due to a stress may protect plant from other different stresses.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2812827&req=5

f5-ijms-10-03371: Influence of different stresses on plant metabolism. The activation of induced resistance leads to the accumulation of numerous defence compounds that may unbalance the equilibrium between primary and secondary metabolism, thus resulting in fitness costs for the plant. On the other hand, the synthesis of secondary metabolites due to a stress may protect plant from other different stresses.
Mentions: Finally, to the other side of the coin, an excessive production of secondary metabolites may be detrimental for the plant’s fitness (Figure 5), in terms of allocation costs and autotoxicity [152,153], though it may be favourable, at least in food plants, which could provide foodstuffs and beverages enriched of bioactive phytochemicals [154].

Bottom Line: In plants, antibiotic compounds can be both preformed (phytoanticipins) and inducible (phytoalexins), the former including saponins, cyanogenic glycosides and glucosinolates.In some cases, the plant defence responses against pathogens and environmental pollutants may overlap, leading to the unspecific synthesis of similar molecules, such as phenylpropanoids.Finally, the synthesis of ethylene and polyamines can be regulated by ozone at level of S-adenosylmethionine (SAM), the biosynthetic precursor of both classes of hormones, which can, therefore, mutually inhibit their own biosynthesis with consequence on plant phenotype.

View Article: PubMed Central - PubMed

Affiliation: Università degli Studi di Milano, Dipartimento di Produzione Vegetale, Milano, Italy. marcello.iriti@unimi.it <marcello.iriti@unimi.it>

ABSTRACT
Chemical defences represent a main trait of the plant innate immune system. Besides regulating the relationship between plants and their ecosystems, phytochemicals are involved both in resistance against pathogens and in tolerance towards abiotic stresses, such as atmospheric pollution. Plant defence metabolites arise from the main secondary metabolic routes, the phenylpropanoid, the isoprenoid and the alkaloid pathways. In plants, antibiotic compounds can be both preformed (phytoanticipins) and inducible (phytoalexins), the former including saponins, cyanogenic glycosides and glucosinolates. Chronic exposure to tropospheric ozone (O(3)) stimulates the carbon fluxes from the primary to the secondary metabolic pathways to a great extent, inducing a shift of the available resources in favour of the synthesis of secondary products. In some cases, the plant defence responses against pathogens and environmental pollutants may overlap, leading to the unspecific synthesis of similar molecules, such as phenylpropanoids. Exposure to ozone can also modify the pattern of biogenic volatile organic compounds (BVOC), emitted from plant in response to herbivore feeding, thus altering the tritrophic interaction among plant, phytophagy and their natural enemies. Finally, the synthesis of ethylene and polyamines can be regulated by ozone at level of S-adenosylmethionine (SAM), the biosynthetic precursor of both classes of hormones, which can, therefore, mutually inhibit their own biosynthesis with consequence on plant phenotype.

Show MeSH
Related in: MedlinePlus