Induction of Jasmonate Biosynthesis in Arbuscular Mycorrhizal Barley Roots,

Abstract

Colonization of barley (Hordeum vulgare cv Salome) roots by an arbuscular mycorrhizal fungus, Glomus intraradices Schenck & Smith, leads to elevated levels of endogenous jasmonic acid (JA) and its amino acid conjugate JA-isoleucine, whereas the level of the JA precursor, oxophytodienoic acid, remains constant. The rise in jasmonates is accompanied by the expression of genes coding for an enzyme of JA biosynthesis (allene oxide synthase) and of a jasmonate-induced protein (JIP23). In situ hybridization and immunocytochemical analysis revealed that expression of these genes occurred cell specifically within arbuscule-containing root cortex cells. The concomitant gene expression indicates that jasmonates are generated and act within arbuscule-containing cells. By use of a near-synchronous mycorrhization, analysis of temporal expression patterns showed the occurrence of transcript accumulation 4 to 6 d after the appearance of the first arbuscules. This suggests that the endogenous rise in jasmonates might be related to the fully established symbiosis rather than to the recognition of interacting partners or to the onset of interaction. Because the plant supplies the fungus with carbohydrates, a model is proposed in which the induction of JA biosynthesis in colonized roots is linked to the stronger sink function of mycorrhizal roots compared with nonmycorrhizal roots.

Mycorrhizal Inoculation Modulates Root Morphology and Root Phytohormone Responses in Trifoliate Orange under Drought Stress

“…The AM seedlings had 28.2 and 40.4% significantly higher root MeJA level than the non-AM seedlings under the WW and the DS conditions, respectively. The increase of MeJA by mycorrhization, in this study, is in agreement with the previous results as shown for several plant species (Hause et al, 2002;Meixner et al, 2005). As stated by LudwigMüller (2010), JA contributed to the life cycle of the AM fungus.…”

Induced Resistance in Mycorrhizal Tomato is correlated to Concentration of Jasmonic Acid

“…Jasmonic acid concentrations were nine times higher in mycorrhizal plants than in non-mycorrhizal shoots, similar level of increase have been reported in mycorrhizal barley [22] and Medicago trucatula [47] . JA may be a systemic signal and dislocated throughout the plant [34] .…”

Exogenous Phytohormones Modulate Mycorrhiza-Induced Changes in Root Hair Configuration of Trifoliate Orange

“…Likewise, an increase of IAA in AM onion (Torelli et al, 2000), AM litchi (Yao et al, 2005) and AM soybean (Meixner et al, 2005) was also well documented. In AM barley and cucumber, considerably higher JA levels had been observed, compared to non-AM controls (Hause et al, 2002;Vierheilig and Piche, 2002). The present study indicated the significantly higher root ZR, MeJA, and ABA concentrations in AMF seedlings than non-AMF seedlings.…”