Jacqueline L. Stroud, Simon J. Kemp, Craig J. Sturrock

In this study, new and traditional organic wastes (green waste compost, farmyard manure (FYM), anaerobic digestate or straw) were ploughed into an arable field experiment at a range of rates (1–3 t C ha⁻¹) and under spring and winter cropping rotations for 5 years. The stability of the soil surface structure (<5 cm) was assessed in Years 3, 4 and 5 to guide the use of organic wastes in arable field management. In conclusion, to achieve a stable soil surface structure, a 150% improvement in aggregate stability would be needed here and ploughing in organic wastes was not a successful management approach on these arable field experiments.

Soil Use and Management. November 2023

Patrick Becker, Fiona B. Naughton, Deborah H. Brotherton, Raul Pacheco-Gomez, Oliver Beckstein, Alexander D. Cameron

The bile acid sodium symporter (BASS) family transports a wide array of molecules across membranes, including bile acids in humans, and small metabolites in plants. These transporters, many of which are sodium-coupled, have been shown to use an elevator mechanism of transport, but exactly how substrate binding is coupled to sodium ion binding and transport is not clear. Here, we solve the crystal structure at 2.3 Å of a transporter from Neisseria meningitidis (ASBT_NM) in complex with pantoate, a potential substrate of ASBT_NM.. Comparison of structures in the presence and absence of pantoate demonstrates that pantoate elicits a conformational change in one of the cross-over helices. This modifies the interface between the two domains that move relative to one another to elicit the elevator mechanism. These results have implications, not only for ASBT_NM but for the BASS family as a whole and indeed other transporters that work through the elevator mechanism.

eLife. November 2023

Xinan Li, Chao Wang, Xun Zhu, Vardis Ntoukakis, Tomislav Cernava & Decai Jin

Leaf-associated microbes play an important role in plant development and response to exogenous stress. Insect herbivores are known to alter the phyllosphere microbiome. However, whether the host plant’s defense against insects is related to the phyllosphere microbiome remains mostly elusive. Here, we investigated bacterial communities in the phyllosphere and endosphere of eight wheat cultivars with differing aphid resistance, grown in the same farmland. Communities of leaf-associated microbes in wheat plants were mainly driven by the host genotype. Members of the genus Exiguobacterium may have adverse effects on wheat aphids. Our findings provide new clues supporting the development of aphid control strategies based on phyllosphere microbiome engineering.

Environmental Microbiome. October 2023

Yinwei Zeng, Inge Verstraeten, Hoang Khai Trinh, Robin Lardon, Sebastien Schotte, Damilola Olatunji, Thomas Heugebaert, Christian Stevens, Mussa Quareshy, Richard Napier, Sara Paola Nastasi, Alex Costa, Bert De Rybel, Catherine Bellini, Tom Beeckman, Steffen Vanneste, Danny Geelen

Upon exposure to light, etiolated Arabidopsis seedlings form adventitious roots (AR) along the hypocotyl. While processes underlying lateral root formation are studied intensively, comparatively little is known about the molecular processes involved in the initiation of hypocotyl AR. AR and LR formation were studied using a small molecule named Hypocotyl Specific Adventitious Root INducer (HYSPARIN) that strongly induces AR but not LR formation. Analysis of HYSPARIN-induced AR formation uncovers an evolutionary conservation of auxin signalling controlling LR and AR induction in Arabidopsis seedlings and identifies SAUR19, OFP4 and AGC2 kinase as novel regulators of AR formation.

New Phytologist. October 2023

Sigurd Ramans-Harborough, Arnout P. Kalverda, Iain W. Manfield, Gary S. Thompson, Martin Kieffer, Veselina Uzunova, Mussa Quareshy, Justyna M. Prusinska, Suruchi Roychoudhry, Ken-ichiro Hayashi, Richard Napier, Charo del Genio, Stefan Kepinski

AUXIN/INDOLE 3-ACETIC ACID (Aux/IAA) transcriptional repressor proteins and the TRANSPORT INHIBITOR RESISTANT 1/AUXIN SIGNALING F-BOX (TIR1/AFB) proteins to which they bind act as auxin coreceptors. While the structure of TIR1 has been solved, structural characterization of the regions of the Aux/IAA protein responsible for auxin perception has been complicated by their predicted disorder. Here, we use NMR, CD and molecular dynamics simulation to investigate the N-terminal domains of the Aux/IAA protein IAA17/AXR3. Our results and approach provide a platform for exploring the functional significance of variation in the Aux/IAA coreceptor family and for understanding the role of intrinsic disorder in auxin signal transduction and other signaling systems.

PNAS.September 2023

Stride, Ben, Dykes, Charlotte, Abolfathi, Soroush, Jimoh, Modupe, Bending, Gary D. and Pearson, Jonathan M

The transport of microplastics within urban water systems remains poorly understood, with little prior research on their behaviour within manhole configurations. This study represents the first to measure and model the transport dynamics of microplastics within circular and square manholes under different hydraulic scenarios. The transport and fate of polyethylene (PE) was quantified and compared to solutes (Rhodamine WT dye) using energy losses, residence time distributions (RTDs), and mixing models within surcharging and overflowing manholes. The bulk mass of solute and PE concentrations followed similar flow paths across all conditions except for 17.3 ± 7.9 % of PE mass that was immobilized in a dead zone above the inlet pipe for manholes with a surcharge to pipe diameter ratio ≥2. Consequently, these microplastics only exit after a significant change in hydraulic regime occurs, causing microplastics to be at risk of being contaminated over a prolonged duration. No significant mixing differences for PE and solutes were found between manhole geometries. The deconvolution method outperformed the ADZ model with goodness of fit (R_t²) values of 0.99 (0.60) and 1.00 (0.89) for PE and solute mixing respectively. This establishes the deconvolution method as the first mixing model to accurately predict microplastic mixing.

Science of the Total Environment. July 2023