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hubie [soylentnews.org] writes:

Plants know which direction is up, but it was never entirely clear how they know. A brief blurb [sciencemag.org] in the most recent Science summarizes a paper [pnas.org] that shows how plants are able to use built-in tilt meters they have in their cells.

Gravity-sensing cells in plants contain tiny grains of starch called statoliths. The orientation of the statoliths changes with the plant's orientation. The gravity-sensing cells respond to even the slightest tilt off of the established plane. Plant statoliths seem to evade the rules of physics that govern other granular materials. In live-cell imaging of young wheat shoots, Bérut et al. observed that statolith piles behave more like slowly creeping liquids than like granular accumulations. The reason is that the individual statoliths are always jiggling around, perhaps because of interactions with the plant cytoskeleton.

Paper reference: 10.1073/pnas.1801895115 (2018)

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