Dynamic changes in root acidity as it encounters a barrierbr />
The local dynamic acidification at the root surface related to its growth is altered by the root tip encountering a barrier to growth. TA pH-sensitive fluorescent dye has been put outside the root and becomes brighter as the local area around the root becomes less acidic. When the root hits a barrier, it "slips" out sideways and the region of the root that becomes strecthed shows a sustained local increase in pH (reduced acidity) that likely reflects this region responsiding to the mechanical stimualtion by trying to slow its growth. Time lapsed over 2 hrs. Originally published in The Plant Cell 21: 2341-2356. (C) The Plant Cell.

For more research into this response see:
Monshausen et al. (2009) The Plant Cell 21: 2341-2356

Monshausen and Gilroy (2009) Current Opinion in Plant Sciences 12:766–772