Water channels or aquaporins are the main pathways of water transport. Both the existence and function of aquaporins in die guard cells of Vicia faba L. were investigated both by using RD28 cDNA and RD28 antibody as probes, and by controlling stomatal movement as a parameter combined with antibody and inhibitor of aquaporins respectively. The results revealed that RD28 mRNA, encoding a plasma membrane aquaporin, expressed in ale mesophyll cells and vascular tissues of V. faba, especially in guard cells. And the location of RD28-like proteins was mainly on plasma membrane of guard cells. The addition of 25 mumol/L HgCl2, an aquaporin blocker, and antibody of RD28 as well, greatly suppressed the stomatal opening or guardcell protoplast swelling induced by fusicoccin and light, and closing induced by abscisic acid. However, 5 mmol/L, beta-mercaptoethanol, a reverse reagent of aquaporin blocker, reversed the inhibitory effect of HgCl2 Pretreatment oil stomatal opening ( i.e., HgCl2 was removed after HgCl2 pretreatment for 10 min). The results suggest that the aquaporins in V. faba are associated with stomatal movement.
