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Apoplastic pH in corn root gravitropism: A laser scanning confocal microscopy measurement
Author(s) -
Taylor Douglas P.,
Slattery James,
Leopold A. Carl
Publication year - 1996
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1996.tb00475.x
Subject(s) - confocal laser scanning microscopy , apoplast , confocal microscopy , gravitropism , biophysics , confocal , chemistry , zea mays , laser scanning , botany , biology , laser , agronomy , optics , biochemistry , microbiology and biotechnology , physics , cell wall , arabidopsis , gene , mutant
The ability to measure the pH of the apoplast in situ is of special interest as a test of the cell wall acidification theory. Optical sectioning of living seedlings of corn roots using the laser scanning confocal microscope (LSCM) permits us to make pH measurements in living tissue. The pH of the apoplast of corn roots was measured by this method after infiltration with CI‐NERF, a pH‐sensitive dye, along with Texas Red Dextran 3000, a pH‐insensitive dye, as an internal standard. In the elongation zone of corn roots, the mean apoplastic pH was 4.9. Upon gravitropic stimulation, the pH on the convex side of actively bending roots was 4.5. The lowering of the apoplastic pH by 0.4 units appears to be sufficient to account for the increased growth on that side. This technique provides site‐specific evidence for the acid growth theory of cell elongation. The LSCM permits measurements of the pH of living tissues, and has a sensitivity of approximately 0.2 pH units.