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- Title
Fungal hypaphorine reduces growth and induces cytosolic calcium increase in root hairs of Eucalyptus globulus.
- Authors
A. Dauphin; J. Gérard; F. Lapeyrie; V. Legué
- Abstract
Summary. Root hairs are tubular cells resulting from a tip-localized growth in which calcium ions play a key role. Hypaphorine, an indole alkaloid secreted by the fungus Pisolithus microcarpus during the formation of ectomycorrhizae with the host plant Eucalyptus globulus, inhibits root hair tip growth. Hypaphorine-induced inhibition is linked to a transient depolarization of the plasma membrane and a reorganization of the actin and microtubule cytoskeletons. Here we investigated the activity of hypaphorine on calcium distribution in E. globulus root hairs with the ratiometric fluorochrome calcium indicator Indo-1. In 85% of actively growing root hairs, a significant but modest calcium gradient between the apex and the base was observed due to an elevated cytoplasmic calcium concentration at the apical tip. Following exposure to 1 mM hypaphorine, the apical and basal cytoplasmic Ca2+ concentration increased in 70 and 77% of the hairs, respectively, 10 min after treatment. This led to a reduced calcium gradient in 81% of the cells. The hypothetical links between calcium concentration elevation, regulation of actin cytoskeleton dynamics, and root hair growth inhibition in response to hypaphorine treatment are discussed.
- Subjects
ROOT hairs (Botany); CALCIUM ions; INDOLE alkaloids; ECTOMYCORRHIZAS; PLANT diseases; HYPAPHORINE
- Publication
Protoplasma, 2007, Vol 231, Issue 1/2, p83
- ISSN
0033-183X
- Publication type
Article
- DOI
10.1007/s00709-006-0240-9