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bioRxiv · 10.64898/2026.05.13.723781

Root hairs and mycorrhiza represent alternative phylogenetically conserved strategies for belowground absorptive surface maximization

Bergmann, J.·Lachaise, T.·Barfuss, K. M.·Bretherick, E.·Matthus, E.·van Kleunen, M.·Rillig, M. C.
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Abstract

O_LIPlants take up nutrients from the soil while investing in absorptive root surface or mycorrhizal partners. Root hairs - a major structure for nutrient uptake and cheap to build - increase the absorptive root surface. As such they are an important component of plant resource economics but largely neglected in root economic concepts so far. C_LIO_LIThis is mainly due to data scarcity, which we set out to overcome by measuring root-hair traits on 82 European grassland species in a greenhouse experiment. Using fluorescence and light microscopy, root-hair length and incidence was measured along with mycorrhizal colonization. C_LIO_LIWe found a phylogenetically conserved trade-off between plant investment into root hairs and mycorrhiza. A similar trade-off between root-hair incidence and mycorrhiza occurred at the intraspecific level, while patterns were heterogeneous among species. Plant species with high colonization rates showed the highest variability in root-hair incidence. C_LIO_LIWe conclude that plants vary along a gradient ranging from investment into root hairs as part of a "do-it-yourself" strategy to collaboration with mycorrhizal fungi while showing intraspecific variation in root-hair incidence. These findings demonstrate that root hairs play a fundamental role in fine-root trait variation and need to be considered when studying belowground plant economic strategies. C_LI

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Bergmann, J., Lachaise, T., Barfuss, K. M., Bretherick, E., Matthus, E., van Kleunen, M., Rillig, M. C.. 2026-05-14. Root hairs and mycorrhiza represent alternative phylogenetically conserved strategies for belowground absorptive surface maximization. https://doi.org/10.64898/2026.05.13.723781

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