Metal-directed root foraging in hyperaccumulators is masked in soil systems.

Authors

Lanfang Hu, Xinhui Liu, Dan Sun, Yetao Tang, Lena Q Ma, Jean-Louis Morel, Yue Cao, Rongliang Qiu

Published in

Bioresource technology. Pages 135781. Sep 05, 2026. Epub Sep 05, 2026.

Abstract

Metal hyperaccumulators are promising plants for phytoextraction, but the root traits that help them grow toward metal-rich soil remain unclear. Metal-directed root foraging has been proposed as a unique trait of hyperaccumulators, yet inconsistent observations have obscured its functional significance. Here, we combined a meta-analysis of 128 published observations with split-root experiments in Sedum alfredii to evaluate the recurrence, environmental sensitivity, and physiological relevance of metal-directed root foraging. A meta-analysis showed a broad but context-dependent tendency for hyperaccumulators to allocate more roots to metal-enriched patches, and this response was positively associated with shoot metal accumulation and biomass. However, this response was strongly shaped by soil conditions, particularly soil texture and soil source. Split-root experiments further revealed a clear ecotype-specific response in hydroponics. The hyperaccumulating ecotype (HE) allocated more than 60 % of its root biomass to the Cd-enriched compartment, whereas the non-hyperaccumulating ecotype (NHE) showed reduced root allocation to this compartment. This ecotype-specific contrast was not fully retained in the tested soil system: Cd-directed foraging by HE was no longer detectable, whereas Cd avoidance by NHE persisted. These findings identify metal-directed root foraging as a recurrent but soil-dependent trait of hyperaccumulators. By showing that soil conditions can constrain the detectability of this trait, our study reconciles inconsistent observations and points to soil management as a potential strategy to strengthen root foraging and enhance phytoextraction in contaminated soils.

PMID:
42700901
Bibliographic data and abstract were imported from PubMed on 06 Sep 2026.

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