Mycorrhizal fungi and nonhydraulic root signals of soil drying.

We propose that mycorrhizal colonization of roots alters nonhydraulic root to shoot communication of soil drying. Split-root rose (Rosa hybrida L. cv Samantha) plants-one side of the root system colonized by Glomus intraradices Schenck & Smith, the other side nonmycorrhizal-displayed different stomatal conductances upon partial drying, depending upon whether mycorrhizal or nonmycorrhizal roots were dried. No differences in leaf water status were observed among control plants and those whose mycorrhizal or nonmycorrhizal roots were dried.