Bundle sheath cells of small veins in maize leaves are the location of uptake from the xylem.
Rb(+) as a tracer for K(+) was used to test the hypothesis that uptake of K(+) from xylem vessels of small veins into the symplast of maize leaves occurs at the xylem/bundle sheath cell interface. 22.5 min after immersing cut leaves into 20 mM RbCl+1 mM KCl, Rb(+) appeared in the cells of the leaves. Sections of these leaves were freeze-dried. In cryo-thin sections (5 microm), (85)Rb(+) and (41)K(+) content was determined by laser microprobe mass analysis with a large resolution of about 1 microm. Determining the ratio of (85)Rb(+) to (41)K(+) in the cell walls and cytosols of bundle sheath cells, mesophyll cells, and in the cells between the xylem elements resulted in the following picture: In small veins, Rb(+) entered the symplast directly at the xylem/bundle sheath cell interface.
Keunecke
M
M
Center for Biochemistry and Molecular Biology, University of Kiel, Leibnizstr. 11, D-24098 Kiel, Germany.
Lindner
B
B
Seydel
U
U
Schulz
A
A
Hansen
U P
UP
D017136:Ion Transport; D018515:Plant Leaves / Q000166:cytology / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D012413:Rubidium / Q000378:metabolism; D003313:Zea mays / Q000166:cytology / Q000378:metabolism*
D012413:Rubidium; D011188:Potassium