Potassium deficiency inhibits lateral root development in tobacco seedlings by changing auxin distribution

Abstract

Aims Potassium deficiency (LK) is a common abiotic stress that affects plant root development. We aimed to identify the role of auxin in LK effects on root growth. Methods We investigated the effects of LK on the formation and elongation of first-and second-order lateral roots (LRs), auxin concentration, DR5::GUS expression, [ 3 H]IAA transport and the expressions of six PIN genes in roots of tobacco plants. We also examined the effects of exogenous auxin (NAA) and a transport inhibitor (NPA) on LR growth and DR5::GUS expression. Results Potassium deficiency reduced root growth, mostly by impairing the formation and elongation of first-order LRs. Indole acetic acid (IAA) concentration and DR5::GUS expression levels decreased in leaves and roots subjected to LK, indicating that LK affected auxin distribution. [ 3 H]IAA transport and the expression levels of PIN genes were reduced by LK, showing that auxin polar transport was inhibited by LK. Application of NAA to LK-treated plants increased first-order LR formation and elongation to levels similar to the control, an outcome that was consistent with the similarity in DR5::GUS expression levels between treatments. NPA acted in a converse manner. Conclusions Potassium deficiency inhibited LR formation and elongation in tobacco plants by shifting auxin distribution.

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The Dead Can Nurture: Novel Insights into the Function of Dead Organs Enclosing Embryos

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