Dynamic changes in root acidity as it grows

As a root grows, it undergoes rounds of local acidification at its surface that appear to relate to the expansion process of its cells. The highly dynamic nature of these waves of altered acidity can be seen by putting a pH-sensitive fluorescent dye outside the root. As the root acidifies its surroundings, the green fluorescence from the reporter is reduced. Things are pretty dynamic! Time lapsed over 2 hrs.

For more research into this response see:
Monshausen et al (2011) The Plant Journal 65: 309-318

Cosgrove (2005) Nature Reviews in Molecular and Cellular Biology 6:850-861