Summary Metallophytes constitute powerful models for the study of metal homeostasis, adaptation to extreme environments and the evolution of naturally selected traits. Arabidopsis halleri is a pseudometallophyte which shows constitutive zinc/cadmium (Zn/Cd) tolerance and Zn hyperaccumulation but high intraspecific variability in Cd accumulation. To examine the molecular basis of the variation in metal tolerance and accumulation, ionome, transcriptome and cell wall glycan array profiles were compared in two genetically close A. halleri populations from metalliferous and nonmetalliferous sites in Northern Italy. The metallicolous population displayed increased tolerance to and reduced hyperaccumulation of Zn, and limited accumulation of Cd, as well as altered metal homeostasis, compared to the nonmetallicolous population. This correlated well with the differential expression of transporter genes involved in trace metal entry and in Cd/Zn vacuolar sequestration in roots. Many cell wall‐related genes were also more highly expressed in roots of the metallicolous population. Glycan array and histological staining analyses demonstrated that there were major differences between the two populations in terms of the accumulation of specific root pectin and hemicellulose epitopes. Our results support the idea that both specific cell wall components and regulation of transporter genes play a role in limiting accumulation of metals in A. halleri at contaminated sites.

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Rhizospheres are microecological zones at the interface of roots and soils. Interactions between bacteria and roots are critical for maintaining plant and soil health but are difficult to study because of constraints inherent in working with underground systems. We have developed an in-situ rhizosphere imaging system based on transparent soils and molecular probes that can be imaged using confocal microscopy. We observed spatial patterning of polysaccharides along roots and on cells deposited into the rhizosphere and also co-localised fluorescently tagged soil bacteria. These studies provide insight into the complex glycan landscape of rhizospheres and suggest a means by which root / rhizobacteria interactions can be non-disruptively studied.

Washed textiles can remain malodorous and dingy due to the recalcitrance of soils. Recent work has found that ‘invisible’ soils such as microbial extracellular DNA (eDNA) play a key role in the adhesion of extracellular polymeric substances that form matrixes contributing to these undesirable characteristics. Here we report the application of an immunostaining method to illustrate the cleaning mechanism of a nuclease (DNase I) acting upon eDNA. Extending previous work that established a key role for eDNA in anchoring these soil matrixes, this work provides new insights into the presence and effective removal of eDNA deposited on fabrics using high-resolution in-situ imaging. Using a monoclonal antibody specific to Z-DNA, we showed that when fabrics are washed with DNase I, the incidence of microbial eDNA is reduced. As well as a quantitative reduction in microbial eDNA, the deep cleaning benefits of this enzyme are shown using confocal microscopy and imaging analysis of T-shirt fibers. To the best of our knowledge, this is the first time the use of a molecular probe has been leveraged for fabric and homecare-related R&D to visualize eDNA and evaluate its removal from textiles by a new-to-laundry DNase enzyme. The approaches described in the current work also have scope for re-application to identify further cleaning technology.

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