Figure 1.

Electron Microscopic Localization of LeSUT4.

(A) Immunogold labeling of the sieve element plasma membrane in a potato petiole transverse section using anti-SUT4 antiserum.

(B) Magnification of the plasma membranes of two adjacent sieve elements (boxed in [A]).

(C) Immunogold labeling of a sieve element plasma membrane of tomato adjacent to a phloem parenchyma cell.

(D) Control with IgG-enriched preimmune serum on a transverse section of a sieve element in a tomato petiole.

(E) Magnification of the region boxed in (D) indicating no label of the plasma membrane.

Note the nonspecific cross-reaction of preimmune and immune serum with phloem protein aggregates. cc, companion cells; cw, cell wall; pp, phloem parenchyma cell; se, sieve element.