Electrical signalling and cytokinins mediate effects of light and root cutting on ion uptake in intact plants

Sergey Shabala, Jiayin Pang, Meixue Zhou, Lana Shabala, Tracey A. Cuin, Peter Nick, Lars H. Wegner

    Research output: Contribution to journalArticlepeer-review

    31 Citations (Scopus)

    Abstract

    Nutrient acquisition in the mature root zone is under systemic control by the shoot and the root tip. In maize, exposure of the shoot to light induces short-term (within 1-2 min) effects on net K+ and H+ transport at the root surface. H+ efflux decreased (from -18 to -12 nmol m-2 s-1) and K+ uptake (∼2 nmol m -2 s-1) reverted to efflux (∼-3 nmol m-2 s-1). Xylem probing revealed that the trans-root (electrical) potential drop between xylem vessels and an external electrode responded within seconds to a stepwise increase in light intensity; xylem pressure started to decrease after a ∼3 min delay, favouring electrical as opposed to hydraulic signalling. Cutting of maize and barley roots at the base reduced H+ efflux and stopped K+ influx in low-salt medium; xylem pressure rapidly increased to atmospheric levels. With 100 mm NaCl added to the bath, the pressure jump upon cutting was more dramatic, but fluxes remained unaffected, providing further evidence against hydraulic regulation of ion uptake. Following excision of the apical part of barley roots, influx changed to large efflux (-50 nmol m-2 s-1). Kinetin (2-4 μ m), a synthetic cytokinin, reversed this effect. Regulation of ion transport by root-tip-synthesized cytokinins is discussed.

    Original languageEnglish
    Pages (from-to)194-207
    Number of pages14
    JournalPlant, Cell and Environment.
    Volume32
    Issue number2
    DOIs
    Publication statusPublished - 2009

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