Uncharted routes: exploring the relevance of auxin movement via plasmodesmata

Abstract

Auxin is an endogenous small molecule with an incredibly large impact on growth and development in plants. Movement of auxin between cells, due to its negative charge at most physiological pHs, strongly relies on families of active transporters. These proteins import auxin from the extracellular space or export it into the same. Mutations in these components have profound impacts on biological processes. Another transport route available to auxin, once the substance is inside the cell, are plasmodesmata connections. These small channels connect the cytoplasms of neighbouring plant cells and enable flow between them. Interestingly, the biological significance of this latter mode of transport is only recently starting to emerge with examples from roots, hypocotyls and leaves. The existence of two transport systems provides opportunities for reciprocal cross-regulation. Indeed, auxin levels influence proteins controlling plasmodesmata permeability, while cell–cell communication affects auxin biosynthesis and transport. In an evolutionary context, transporter driven cell–cell auxin movement and plasmodesmata seem to have evolved around the same time in the green lineage. This highlights a co-existence from early on and a likely functional specificity of the systems. Exploring more situations where auxin movement via plasmodesmata has relevance for plant growth and development, and clarifying the regulation of such transport, will be key aspects in coming years.This article has an associated Future Leader to Watch interview with the author of the paper.

Callose accumulation in specific phloem cell types reduces axillary bud growth in Arabidopsis thaliana

“…PIN proteins, which are known to be involved in bud activation, might therefore also play roles in the less studied process of postactivation growth. Interplay between cell-cell communication and hormonal networks have already been reported in other contexts (Paterlini, 2020).…”

Auxin fluxes through plasmodesmata

“…Recent studies have demonstrated clearly that diffusion through plasmodesmata is a key component of the auxin transport machinery, both affecting the auxin distribution and, most importantly, contributing to plant phenotypes (Paterlini, 2020). Manipulating auxin diffusion through plasmodesmata (using lines that regulate callose levels) has been shown to affect auxin distributions, phototropism, lateral root emergence and leaf hyponasty.…”

Integrating transcriptome and metabolome analyses of the response to cold stress in pumpkin (Cucurbita maxima)

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