Hydropowered Pollen

A tension-sensing ion channel regulates hydration and germination in pollen.

Karen Zusi
Jan 31, 2016

ADJUST OR BUST: Pollen grains (green) and their tubes (white) that lack the MSL8 ion channel leak their cellular contents (blue) during germination.GREG JENSEN AND ERIC HAMILTON

EDITOR'S CHOICE IN PLANT BIOLOGY

The paper
E.S. Hamilton et al., “Mechanosensitive channel MSL8 regulates osmotic forces during pollen hydration and germination,” Science, 350:438-41, 2015.

Getting hydrated
When a dry pollen grain first lands on a flower’s stigma, secretions from the flower rehydrate the grain. Eventually, enough inner pressure builds up for the pollen to grow a tube towards the flower’s ovaries. Elizabeth Haswell, a plant molecular biologist at Washington University in Saint Louis, wanted to know how the grain’s cells sense and manage these mechanical changes.

Electrophysiology
Haswell suspected an ion channel was involved, given that membrane tension-sensing channels protect Escherichia coli from taking in too much water. Fluorescent tagging revealed that a related gene, MSL8, was active in Arabidopsis...