Abstract
Protein acetylation affects gene expression, as well as other processes in cells, and it might be dependent on the availability of the metals. However, whether iron chelating compounds (siderophores) can have an effect on the acetylation process in plant roots is largely unknown. In the present study, western blotting and confocal microscopy was used to examine the degree of acetylation of histone H3 and alpha tubulin in Pinus sylvestris root cells in the presence of structurally different siderophores. The effect of metabolites that were produced by pathogenic and mycorrhizal fungi was also assessed. No effect was observed on histone acetylation. By contrast, the metabolites of the pathogenic fungus were able to decrease the level of microtubule acetylation, whereas treatment with iron-free ferrioxamine (DFO) was able to increase it. This latter was not observed when ferrioxamine-iron complexes were used. The pathogen metabolites induced important modifications of cytoskeleton organization. Siderophores also induced changes in the tubulin skeleton and these changes were iron-dependent. The effect of siderophores on the microtubule network was dependent on the presence of iron. More root cells with a depolymerized cytoskeleton were observed when the roots were exposed to iron-free siderophores and the metabolites of pathogenic fungi; whereas, the metabolites from mycorrhizal fungi and iron-enriched forms of siderophores slightly altered the cytoskeleton network of root cells. Collectively, these data indicated that the metabolites of pathogenic fungi mirror siderophore action, and iron limitation can lead to enhanced alternations in cell structure and physiology.
Highlights
Previous studies have demonstrated that iron plays a role in fungal-host interactions in both leaves [1,2,3] and roots [4,5,6,7,8]
The response of Pinus sylvestris roots to the application of different siderophores mirrored the response of the same roots to the application of the total metabolites secreted by either pathogenic or mycorrhizal fungi, and it was manifested as an imbalance in the distribution of elements that were measured in key cell compartments [13]
Filter paper overgrown with a two-week old mycelial mat was placed on the roots of P. sylvestris seedlings under cellophane foil growing in the conditions previously stated to compare the response of P. sylvestris root cell to the different siderophore treatments with and on metabolites produced by fungi
Summary
Previous studies have demonstrated that iron plays a role in fungal-host interactions in both leaves [1,2,3] and roots [4,5,6,7,8]. Trichostatin A, a derivative of hydroxamic acid, inhibits deacetylases, and provides a direct link between protein acetylation and microbial metabolites [16] It is not known whether the acetylation in plants that is dependent on hydroxamic acid derivatives is affected by siderophores produced by fungi. It is not known either whether siderophores depended acetylation processes result in plant death or regulate mutualistic symbiosis. It is of importance, as high levels of iron can promote cell death and contribute to the proliferation of necrotrophic pathogens [5], while blocking the formation of a symbiotic relationship. The availability of cofactors likely affect changes in acetylation, among which iron is the strongest [18]
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