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The Rhizobium sp. strain NGR234 systemically suppresses arbuscular mycorrhizal root colonization in a split‐root system of barley ( Hordeum vulgare )
Author(s) -
Khaosaad Thanasan,
Staehelin Christian,
Steinkellner Siegrid,
HageAhmed Karin,
Ocampo Juan Antonio,
GarciaGarrido Jose Manuel,
Vierheilig Horst
Publication year - 2010
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.2010.01396.x
Subject(s) - rhizobia , biology , colonization , rhizosphere , hordeum vulgare , rhizobium , inoculation , symbiosis , strain (injury) , nod factor , microbiology and biotechnology , bacteria , botany , horticulture , poaceae , genetics , anatomy
Nitrogen‐fixing bacteria (rhizobia) form a nodule symbiosis with legumes, but also induce certain effects on non‐host plants. Here, we used a split‐root system of barley to examine whether inoculation with Rhizobium sp. strain NGR234 on one side of a split‐root system systemically affects arbuscular mycorrhizal (AM) root colonization on the other side. Mutant strains of NGR234 deficient in Nod factor production (strain NGRΔ nodABC ), perception of flavonoids (strain NGRΔ nodD1 ) and secretion of type 3 effector proteins (strain NGRΩ rhcN ) were included in this study. Inoculation resulted in a systemic reduction of AM root colonization with all tested strains. However, the suppressive effect of strain NGRΩ rhcN was less pronounced. Moreover, levels of salicylic acid, an endogenous molecule related to plant defense, were increased in roots challenged with rhizobia. These data indicate that barley roots perceived NGR234 and that a systemic regulatory mechanism of AM root colonization was activated. The suppressive effect appears to be Nod factor independent, but enhanced by type 3 effector proteins of NGR234.