Arbuscular mycorrhizas (AMs) have the ability to enhance drought tolerance of citrus, but the underlying mechanisms have not been clearly elucidated. Considering the strong association of cell membrane fatty acid (FA) unsaturation with plant drought tolerance, the present study hypothesized that AM fungi (AMF) modulated the composition and unsaturation of FAs to enhance drought tolerance of host plants. Drought-sensitive citrus rootstocks, trifoliate orange (Poncirus trifoliata) seedlings, were inoculated with AMF (Funneliformis mosseae) for 3 months and were subsequently exposed to drought stress (DS) for 8 weeks. Mycorrhizal seedlings exhibited better plant growth performance, higher leaf water potential and lower root abscisic acid concentrations under both well-watered (WW) and DS conditions. Arbuscular mycorrhiza fungus inoculation considerably increased root methyl oleate (C18:1), methyl linoleate (C18:2) and methyl linolenate (C18:3N3) concentrations under both WW and DS conditions, and root methyl palmitoleate (C16:1) concentrations under WW, while it decreased root methyl stearate (C18:0) levels under both WW and DS. These changes in the composition of FAs of mycorrhized roots resulted in higher unsaturation index of root FAs, which later aided in reducing the oxidative damage on account of lower concentration of malondialdehyde and superoxide radicals. The changes of these FAs were a result of AMF-up-regulating root FA desaturase 2 (PtFAD2), FA desaturase 6 (PtFAD6) and Δ9 FA desaturase (PtΔ9) genes under WW and PtFAD2, PtFAD6 and Δ15 FA desaturase (PtΔ15) genes under DS conditions. Our results confirmed that mycorrhization brought significant changes in root FA compositions, in addition to regulation of gene expression responsible for increasing the unsaturation level of FAs, a predisposing physiological event for better drought tolerance of citrus.
Root-hair growth and development regulated by soil microbes is associated with auxin. In this background, we hypothesized that mycorrhizal fungal inoculation induces greater root-hair growth through stimulated auxin synthesis and transport under water stress conditions. Trifoliate orange (Poncirus trifoliata) was inoculated with an arbuscular mycorrhizal (AM) fungus (Funneliformis mosseae) under well-watered (WW) and drought stress (DS) for 9 weeks. Compared with non-AM seedlings, AM seedlings displayed significantly higher density, length, and diameter of root hairs and root indoleacetic acid (IAA) level, whereas lower total root IAA efflux, regardless of soil moisture status. Root PtYUC3 and PtYUC8 involved in IAA biosynthesis were up-regulated by mycorrhization under WW and DS, whereas AM-modulated expression in PtTAA1, PtTAR2, PtYUC4, and PtYUC6 depended on status of soil moisture. Mycorrhizal inoculation down-regulated the transcript level of root auxin efflux carriers like PtPIN1 and PtPIN3, whereas significantly up-regulated the expression of root auxin-species influx carriers like PtABCB19 and PtLAX2 under DS. These results indicated that AMF-stimulated greater root-hair growth of trifoliate orange under DS that is independent on AMF species is related with mycorrhiza-modulated auxin synthesis and transport, which benefits the host plant to enhance drought tolerance.
- MeSH
- biologický transport MeSH
- fyziologický stres * MeSH
- Glomeromycota růst a vývoj fyziologie MeSH
- kyseliny indoloctové metabolismus MeSH
- messenger RNA genetika metabolismus MeSH
- mykorhiza růst a vývoj fyziologie MeSH
- období sucha * MeSH
- počet mikrobiálních kolonií MeSH
- Poncirus genetika růst a vývoj mikrobiologie fyziologie MeSH
- regulace genové exprese u rostlin MeSH
- rostlinné geny MeSH
- rostlinné proteiny genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Publikační typ
- abstrakt z konference MeSH
We investigated the hypolipidemic effect of glycyrrhizic acid (GA) focused on the mRNA expression and hepatic HMG-CoA reductase (HMGR) activity in hamsters fed a high-fat diet. Male Syrian Golden hamsters were fed a high fat diet for 8 weeks for induction of dyslipidemia and were treated with GA and fenofibrate. The concentrations of plasma total cholesterol and triglyceride were significantly lower in the GA-treated group than in the control group. The GA treatment significantly decreased Apo B, Lp(a), and cholesterol-ester-transport protein (CETP) concentrations, but increased Apo A-I levels and the Apo A-I/ Apo B ratio. The contents of cholesterol and triglyceride in hepatic tissue were significantly lower in the GA group than in the control group. Real-time PCR analysis revealed that HMGR mRNA expression was significantly lower in the GA group than in the control group. These results indicate that GA treatment reduces plasma cholesterol by down-regulating hepatic HMGR mRNA expression in hamsters fed a high fructose-fat diet.
- MeSH
- dietní tuky aplikace a dávkování MeSH
- dyslipidemie farmakoterapie metabolismus MeSH
- financování organizované MeSH
- fruktosa aplikace a dávkování MeSH
- hydroxymethylglutaryl-CoA-reduktasy genetika metabolismus MeSH
- hypolipidemika farmakologie MeSH
- játra metabolismus MeSH
- křečci praví MeSH
- křeček rodu Mesocricetus MeSH
- kyselina glycyrrhizinová farmakologie MeSH
- lipidy krev MeSH
- messenger RNA metabolismus MeSH
- zvířata MeSH
- Check Tag
- křečci praví MeSH
- mužské pohlaví MeSH
- zvířata MeSH
[1st ed.] vii, 152 s. : il.
- Konspekt
- Biochemie. Molekulární biologie. Biofyzika
- NLK Obory
- biologie
