We examined the hypothesis that regulation of plant plasma membrane aquaporins (PIP) under mycorrhiza and / or drought may operate by altering the accumulation of heteromers of different subunit composition. Variation in the ratio of PIP1 and PIP2 monomers has recently been proposed as a novel regulation mechanism, although it has not yet been examined when a mycorrhizal partner is involved. As we showed, the variation of PIPs and their accumulation patterns were complementary in roots and leaves, suggesting systemic coordination. It can be further altered by mycorrhiza, acting as a positive feedback on stomatal conductance and faster recovery