Nucleus size in the host cells of an Arbuscular Mycorrhizal system: a mathematical approach to estimate the role of ploidy and chromatin condensation

Lingua, Graziano; Trotta, Antonio; Prigione, Valeria; Ugoccioni, R.; Berta, Graziella

doi:10.1080/00087114.2005.10589441

Cited by 4 publications

(1 citation statement)

References 54 publications

(27 reference statements)

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“…Although previous studies have been mostly focused on the analysis of relative changes in specific ploidy classes (e.g. 2C and 8C in Berta et al ., ; 2C and 4C in Lingua et al ., ), our analyses detected up to eight distinct classes, ranging between 2C and 256C. In agreement with Berta et al .…”

Section: Discussionsupporting

confidence: 93%

Local endoreduplication as a feature of intracellular fungal accommodation in arbuscular mycorrhizas

et al. 2019

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Summary The intracellular accommodation of arbuscular mycorrhizal (AM) fungi is a paradigmatic feature of this plant symbiosis that depends on the activation of a dedicated signaling pathway and the extensive reprogramming of host cells, including striking changes in nuclear size and transcriptional activity. By combining targeted sampling of early root colonization sites, detailed confocal imaging, flow cytometry and gene expression analyses, we demonstrate that local, recursive events of endoreduplication are triggered in the Medicago truncatula root cortex during AM colonization. AM colonization induces an increase in ploidy levels and the activation of endocycle specific markers. This response anticipates the progression of fungal colonization and is limited to arbusculated and neighboring cells in the cortical tissue. Furthermore, endoreduplication is not induced in M. truncatula mutants for symbiotic signaling pathway genes. On this basis, we propose endoreduplication as part of the host cell prepenetration responses that anticipate AM fungal accommodation in the root cortex.

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Section: Discussionsupporting

confidence: 93%

Local endoreduplication as a feature of intracellular fungal accommodation in arbuscular mycorrhizas

et al. 2019

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Epigenetic control of heavy metal stress response in mycorrhizal versus non-mycorrhizal poplar plants

Cicatelli

Todeschini

Lingua

et al. 2013

Environ Sci Pollut Res

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It was previously shown that arbuscular mycorrhizal fungi (AMF) exert a significant improvement of growth in a tolerant white poplar (Populus alba L.) clone (AL35) grown on Cu- and Zn-polluted soil via foliar alterations in the levels of defence/stress-related transcripts and molecules. However, nothing is known about the epigenetic changes which occur during tolerance acquisition in response to heavy metals (HMs) in the same mycorrhizal vs. non-mycorrhizal poplar plants. In order to analyse the epigenome in leaves of AL35 plants inoculated or not with AMF and grown in a greenhouse on multimetal polluted or unpolluted soil, the Methylation Sensitive Amplification Polymorphism (MSAP) approach was adopted to detect cytosine DNA methylation. Modest changes in cytosine methylation patterns were detected at first sampling (4 months from planting), whereas extensive alterations (hypomethylation) occurred at second sampling (after 6 months) in mycorrhizal plants grown in the presence of HMs. The sequencing of MSAP fragments led to the identification of genes belonging to several Gene Ontology categories. Seven MSAP fragments, selected on the basis of DNA methylation status in treated vs control AL35 leaves at the end of the experiment, were analysed for their transcript levels by means of qRT-PCR. Gene expression varied in treated samples relative to controls in response to HMs and/or AMF inoculation; in particular, transcripts of genes involved in RNA processing, cell wall and amino acid metabolism were upregulated in the presence of AMF with or without HMs.

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Size matters: three methods for estimating nuclear size in mycorrhizal roots of Medicago truncatula by image analysis

et al. 2019

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Background The intracellular accommodation of arbuscular mycorrhizal (AM) fungi involves a profound molecular reprogramming of the host cell architecture and metabolism, based on the activation of a symbiotic signaling pathway. In analogy with other plant biotrophs, AM fungi are reported to trigger cell cycle reactivation in their host tissues, possibly in support of the enhanced metabolic demand required for the symbiosis. Results We here compare the efficiency of three Fiji/ImageJ image analysis plugins in localizing and quantifying the increase in nuclear size - a hallmark of recursive events of endoreduplication - in M. truncatula roots colonized by the AM fungus Gigaspora margarita . All three approaches proved to be versatile and upgradeable, allowing the investigation of nuclear changes in a complex tissue; 3D Object Counter provided more detailed information than both TrackMate and Round Surface Detector plugins. On this base we challenged 3D Object Counter with two case studies: verifying the lack of endoreduplication-triggering responses in Medicago truncatula mutants with a known non-symbiotic phenotype; and analysing the correlation in space and time between the induction of cortical cell division and endoreduplication upon AM colonization. Both case studies revealed important biological aspects. Mutant phenotype analyses have demonstrated that the knock-out mutation of different key genes in the symbiotic signaling pathway block AM-associated endoreduplication. Furthermore, our data show that cell divisions occur during initial stages of root colonization and are followed by recursive activation of the endocycle in preparation for arbuscule accommodation. Conclusions In conclusion, our results indicate 3D Object Counter as the best performing Fiji/ImageJ image analysis script in plant root thick sections and its application highlighted endoreduplication as a major feature of the AM pre-penetration response in root cortical cells. Electronic supplementary material The online version of this article (10.1186/s12870-019-1791-1) contains supplementary material, which is available to authorized users.

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Nucleus size in the host cells of an Arbuscular Mycorrhizal system: a mathematical approach to estimate the role of ploidy and chromatin condensation

Cited by 4 publications

References 54 publications

Local endoreduplication as a feature of intracellular fungal accommodation in arbuscular mycorrhizas

Local endoreduplication as a feature of intracellular fungal accommodation in arbuscular mycorrhizas

Epigenetic control of heavy metal stress response in mycorrhizal versus non-mycorrhizal poplar plants

Size matters: three methods for estimating nuclear size in mycorrhizal roots of Medicago truncatula by image analysis

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