Vision, challenges and opportunities for a Plant Cell Atlas

With growing populations and pressing environmental problems, future economies will be increasingly plant-based. Now is the time to reimagine plant science as a critical component of fundamental science, agriculture, environmental stewardship, energy, technology and healthcare. This effort requires a conceptual and technological framework to identify and map all cell types, and to comprehensively annotate the localization and organization of molecules at cellular and tissue levels. This framework, called the Plant Cell Atlas (PCA), will be critical for understanding and engineering plant development, physiology and environmental responses. A workshop was convened to discuss the purpose and utility of such an initiative, resulting in a roadmap that acknowledges the current knowledge gaps and technical challenges, and underscores how the PCA initiative can help to overcome them.</jats:p

Extracellular Vesicles in the Arbuscular Mycorrhizal Symbiosis: Current Understanding and Future Perspectives

The arbuscular mycorrhizal (AM) symbiosis is an ancient and highly conserved mutualism between plant and fungal symbionts, in which a highly specialized membrane-delimited fungal arbuscule acts as the symbiotic interface for nutrient exchange and signaling. As a ubiquitous means of biomolecule transport and intercellular communication, extracellular vesicles (EVs) are likely to play a role in this intimate cross-kingdom symbiosis, yet, there is a lack of research investigating the importance of EVs in AM symbiosis despite known roles in microbial interactions in both animal and plant pathosystems. Clarifying the current understanding of EVs in this symbiosis in light of recent ultrastructural observations is paramount to guiding future investigations in the field, and, to this end, this review summarizes recent research investigating these areas. Namely, this review discusses the available knowledge regarding biogenesis pathways and marker proteins associated with the various plant EV subclasses, EV trafficking pathways during symbiosis, and the endocytic mechanisms implicated in the uptake of these EVs. [Graphic: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license

Plant carbon nourishment of arbuscular mycorrhizal fungi.

Reciprocal nutrient exchange between the majority of land plants and arbucular mycorrhizal (AM) fungi is the cornerstone of a stable symbiosis. To date, a dogma in the comprehension of AM fungal nourishment has been delivery of host organic carbon in the form of sugars. More recently a role for lipids as alternative carbon source or as a signalling molecule during AM symbiosis was proposed. Here we review the symbiotic requirement for carbohydrates and lipids across developmental stages of the AM symbiosis. We present a role for carbohydrate metabolism and signalling to maintain intraradical fungal growth, as opposed to lipid uptake at the arbuscule as an indispensible requirement for completion of the AM fungal life cycle.Ronelle Roth is supported by the BBSRC grant BB/N008723/1 to Uta Paszkowski

Arbuscular cell invasion coincides with extracellular vesicles and membrane tubules

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bundle sheath defective2, a Mutation That Disrupts the Coordinated Development of Bundle Sheath and Mesophyll Cells in the Maize Leaf.

Within the maize leaf primordium, coordinated cell division and differentiation patterns result in the development of two morphologically and biochemically distinct photosynthetic cell types, the bundle sheath and the mesophyll. The bundle sheath defective2-mutable1 (bsd2-m1) mutation specifically disrupts C4 differentiation in bundle sheath cells in that the levels of bundle sheath cell-specific photosynthetic enzymes are reduced and the bundle sheath chloroplast structure is aberrant. In contrast, mesophyll cell-specific enzymes accumulate to normal levels, and the mesophyll cell chloroplast structure is not perturbed. Throughout mutant leaf development, the large and small subunits of ribulose bisphosphate carboxylase are absent; however, both rbcL and RbcS transcripts accumulate. Moreover, chloroplast-encoded rbcL transcripts accumulate ectopically in mesophyll cells. Although the bundle sheath cell chloroplast structure deteriorates rapidly when plants are exposed to light, this deterioration is most likely a secondary effect resulting from cell-specific photooxidative damage. Therefore, we propose that the Bsd2 gene plays a direct role in the post-transcriptional control of rbcL transcript accumulation and/or translation, both in bundle sheath and mesophyll cells, and an indirect role in the maintenance of bundle sheath cell chloroplast structure