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Mechanosensitive channel MSL8 regulates osmotic forces during pollen hydration and germination

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Science  23 Oct 2015:
Vol. 350, Issue 6259, pp. 438-441
DOI: 10.1126/science.aac6014

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Metered rehydration in pollen grains

When a desiccated pollen grain lands on fertile territory, it rehydrates on the way to activating its growth and metabolic processes. Studying the small plant Arabidopsis, Hamilton et al. have identified a mechanosensory ion channel that responds to the distention of the plasma membrane as the pollen grain rehydrates. With this channel damaged or absent, the pollen grains germinated overenthusiastically but then showed a tendency to burst.

Science, this issue p. 438

Abstract

Pollen grains undergo dramatic changes in cellular water potential as they deliver the male germ line to female gametes, and it has been proposed that mechanosensitive ion channels may sense the resulting mechanical stress. Here, we identify and characterize MscS-like 8 (MSL8), a pollen-specific, membrane tension–gated ion channel required for pollen to survive the hypoosmotic shock of rehydration and for full male fertility. MSL8 negatively regulates pollen germination but is required for cellular integrity during germination and tube growth. MSL8 thus senses and responds to changes in membrane tension associated with pollen hydration and germination. These data further suggest that homologs of bacterial MscS have been repurposed in eukaryotes to function as mechanosensors in multiple developmental and environmental contexts.

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