Arbuscular mycorrhizal fungi (AMF) have important roles in enhancing drought tolerance of host plants, but it is not clear whether and how AMF increase drought tolerance in walnut (Juglans regia). We hypothesized that AMF could activate antioxidant defense systems and heat shock transcription factors (Hsfs) transcription levels to alleviate oxidative damage caused by drought. The walnut variety 'Liaohe No. 1' was inoculated with Diversispora spurca and exposed to well-watered (WW, 75% of the maximum soil water capacity) and drought stress (DS, 50% of the maximum soil water capacity) for 6 weeks. Plant growth, antioxidant defense systems, and expressions of five JrHsfs in leaves were studied. Such drought treatment inhibited root mycorrhizal colonization, while plant growth performance was still improved by AMF inoculation. Mycorrhizal fungal inoculation triggered the increase in soluble protein, glutathione (GSH), ascorbic acid (ASC), and total ASC contents and ascorbic peroxidase and glutathione reductase activities, along with lower hydrogen peroxide (H2O2), superoxide anion radical (O2 •-), and malondialdehyde (MDA) levels, compared with non-inoculation under drought. Mycorrhizal plants also recorded higher peroxidase, catalase, and superoxide dismutase activities than non-mycorrhizal plants under drought. The expression of JrHsf03, JrHsf05, JrHsf20, JrHsf22, and JrHsf24 was up-regulated under WW by AMF, while the expression of JrHsf03, JrHsf22, and JrHsf24 were up-regulated only under drought by AMF. It is concluded that D. spurca induced low oxidative burst in drought-stressed walnut through activating antioxidant defense systems and part Hsfs expressions.

• Klíčová slova
• arbuscular mycorrhiza, heat shock transcription factor, reactive oxygen species, symbiosis, water stress,
• Publikační typ
• časopisecké články MeSH

The Non-invasive Micro-test Technique (NMT) is used to measure dynamic changes of specific ions/molecules non-invasively, but information about hydrogen peroxide (H2O2) fluxes in different classes of roots by mycorrhiza is scarce in terms of NMT. Effects of Funneliformis mosseae on plant growth, H2O2, superoxide radical (O2·-), malondialdehyde (MDA) concentrations, and H2O2 fluxes in the taproot (TR) and lateral roots (LRs) of trifoliate orange seedlings under well-watered (WW) and drought stress (DS) conditions were studied. DS strongly inhibited mycorrhizal colonization in the TR and LRs, whereas mycorrhizal inoculation significantly promoted plant growth and biomass production. H2O2, O2·-, and MDA concentrations in leaves and roots were dramatically lower in mycorrhizal seedlings than in non-mycorrhizal seedlings under DS. Compared with non-mycorrhizal seedlings, mycorrhizal seedlings had relatively higher net root H2O2 effluxes in the TR and LRs especially under WW, as well as significantly higher total root H2O2 effluxes in the TR and LRs under WW and DS. Total root H2O2 effluxes were significantly positively correlated with root colonization but negatively with root H2O2 and MDA concentrations. It suggested that mycorrhizas induces more H2O2 effluxes of the TR and LRs, thus, alleviating oxidative damage of DS in the host plant.

• MeSH
• biomasa MeSH
• fyziologický stres * MeSH
• lineární modely MeSH
• malondialdehyd metabolismus   MeSH
• mykorhiza růst a vývoj   fyziologie   MeSH
• období sucha * MeSH
• peroxid vodíku metabolismus   MeSH
• počet mikrobiálních kolonií MeSH
• Poncirus mikrobiologie   fyziologie   MeSH
• superoxidy metabolismus   MeSH
• voda metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• malondialdehyd MeSH
• peroxid vodíku MeSH
• superoxidy MeSH
• voda MeSH

Plant roots are the first parts of plants to face drought stress (DS), and thus root modification is important for plants to adapt to drought. We hypothesized that the roots of arbuscular mycorrhizal (AM) plants exhibit better adaptation in terms of morphology and phytohormones under DS. Trifoliate orange seedlings inoculated with Diversispora versiformis were subjected to well-watered (WW) and DS conditions for 6 weeks. AM seedlings exhibited better growth performance and significantly greater number of 1st, 2nd, and 3rd order lateral roots, root length, area, average diameter, volume, tips, forks, and crossings than non-AM seedlings under both WW and DS conditions. AM fungal inoculation considerably increased root hair density under both WW and DS and root hair length under DS, while dramatically decreased root hair length under WW but there was no change in root hair diameter. AM plants had greater concentrations of indole-3-acetic acid, methyl jasmonate, nitric oxide, and calmodulin in roots, which were significantly correlated with changes in root morphology. These results support the hypothesis that AM plants show superior adaptation in root morphology under DS that is potentially associated with indole-3-acetic acid, methyl jasmonate, nitric oxide, and calmodulin levels.

• MeSH
• acetáty metabolismus   MeSH
• cyklopentany metabolismus   MeSH
• fyziologická adaptace MeSH
• Glomeromycota metabolismus   fyziologie   MeSH
• kalmodulin metabolismus   MeSH
• kořeny rostlin růst a vývoj   mikrobiologie   MeSH
• kyseliny indoloctové metabolismus   MeSH
• mykorhiza růst a vývoj   MeSH
• období sucha MeSH
• oxid dusnatý metabolismus   MeSH
• oxylipiny metabolismus   MeSH
• Poncirus růst a vývoj   mikrobiologie   MeSH
• regulátory růstu rostlin metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• acetáty MeSH
• cyklopentany MeSH
• indoleacetic acid MeSH Prohlížeč
• kalmodulin MeSH
• kyseliny indoloctové MeSH
• methyl jasmonate MeSH Prohlížeč
• oxid dusnatý MeSH
• oxylipiny MeSH
• regulátory růstu rostlin MeSH