Abstract
Summary Plants reorganize their root architecture to avoid growth into unfavorable regions of the rhizosphere. In a screen based on chimeric repressor gene‐silencing technology, we identified the Arabidopsis thaliana GeBP‐LIKE 4 (GPL4) transcription factor as an inhibitor of root growth that is induced rapidly in root tips in response to cadmium (Cd).We tested the hypothesis that GPL4 functions in the root avoidance of Cd by analyzing root proliferation in split medium, in which only half of the medium contained toxic concentrations of Cd.The wild‐type (WT) plants exhibited root avoidance by inhibiting root growth in the Cd side but increasing root biomass in the control side. By contrast, GPL4‐suppression lines exhibited nearly comparable root growth in the Cd and control sides and accumulated more Cd in the shoots than did the WT. GPL4 suppression also altered the root avoidance of toxic concentrations of other essential metals, modulated the expression of many genes related to oxidative stress, and consistently decreased reactive oxygen species concentrations.We suggest that GPL4 inhibits the growth of roots exposed to toxic metals by modulating reactive oxygen species concentrations, thereby allowing roots to colonize noncontaminated regions of the rhizosphere.
Highlights
Plants are continuously subjected to abiotic stresses
In a screen based on chimeric repressor gene-silencing technology, we identified the Arabidopsis thaliana GLABRA1 ENHANCER BINDING PROTEIN (GeBP)-LIKE 4 (GPL4) transcription factor as an inhibitor of root growth that is induced rapidly in root tips in response to cadmium (Cd)
We tested the hypothesis that GPL4 functions in the root avoidance of Cd by analyzing root proliferation in split medium, in which only half of the medium contained toxic concentrations of Cd
Summary
Plants are continuously subjected to abiotic stresses. When exposed to sublethal levels of abiotic stresses, plants exhibit an array of morphological, physiological and biochemical responses that allow them to tolerate, acclimate to or avoid these stresses. The changes in root architecture occur when plants adjust the growth of their primary and secondary roots to adapt to the environment (e.g. patchy nutrient distribution in soil). This involves the development of new lateral roots and the inhibition/ promotion of primary root growth. Sulfur deficiency induces the formation of lateral roots in Arabidopsis thaliana plants (Remans et al, 2006; Gruber et al, 2013). Such changes in growth enable the root to explore increased soil volumes in search of nutrient-rich patches. Restructuring of the whole root architecture is a biologically important phenomenon for plant survival and yield, but has not received
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