Reaction of intact sieve elements to injury incurred by a "small tip"
microelectrode.
The direction of fluorochrome translocation is from right to left in (A) and (B). Time scans of an intact phloem region stained by locally applied RH-160 and translocated HPTSA with double detection of RH-160 (red) and HPTSA (green), are shown. The tip diameter of the microelectrode filled with sulforhodamine G is approximately 0.1 micrometer.
(A) Careful insertion of the microelectrode into the right sieve element. The P plastids (arrowheads) remain intact despite the penetration of the electrode.
(B) After retraction of the microelectrode, the P plastids of the right sieve element explode, whereas the plastids of the left sieve element are still intact (arrowheads). In the right sieve element, a large plug builds up in front of the sieve plate.
ME = microelectrode SE = sieve element; SP = sieve plate