Mycorrhizal-induced calmodulin mediated changes in antioxidant enzymes and growth response of drought-stressed trifoliate orange

Abstract

Trifoliate orange [Poncirus trifoliata (L) Raf.] is considered highly arbuscular mycorrhizal (AM) dependent for growth responses through a series of signal transductions in form of various physiological responses. The proposed study was carried out to evaluate the effect of an AM fungus (Funneliformis mosseae) on growth, antioxidant enzyme (catalase, CAT; superoxide dismutase, SOD) activities, leaf relative water content (RWC), calmodulin (CaM), superoxide anion (O2•−), and hydrogen peroxide (H2O2) concentrations in leaves of the plants exposed to both well-watered (WW) and drought stress (DS) conditions. A 58-day of DS significantly decreased mycorrhizal colonization by 60% than WW. Compared to non-AM seedlings, AM seedlings displayed significantly higher shoot morphological properties (plant height, stem diameter, and leaf number), biomass production (shoot and root fresh weight) and leaf RWC, regardless of soil water status. AM inoculation significantly increased CaM and soluble protein concentrations and CAT activity, whereas significantly decreased O2•− and H2O2 concentration under both WW and DS conditions. The AM seedlings also exhibited significantly higher Cu/Zn-SOD and Mn-SOD activities than the non-AM seedlings under DS but not under WW, which are triggered by higher CaM levels in AM plants on the basis of correlation studies. Further, the negative correlation of Cu/Zn-SOD and Mn-SOD activities with O2•− and H2O2 concentration showed the DS-induced ROS scavenging ability of CaM mediated SODs under mycorrhization. Our results demonstrated that AM-inoculation elevated the synthesis of CaM in leaves and up-regulated activities of the antioxidant enzymes, thereby, repairing the possible oxidative damage to plants by lowering the ROS accumulation under DS condition.

Alleviation of Drought Stress in White Clover after Inoculation with Arbuscular Mycorrhizal Fungi

“…It seems that AMF inoculation was involved in the increase in root soluble protein concentrations under DS. Similar finding was reported by Huang et al (2014) in trifoliate orange plants. The increase of soluble protein under mycorrhization might be involved in the decrease in RNA disintegration and in stimulating new protein production under DS.…”

Mycorrhizal Fungi Regulate Root Responses and Leaf Physiological Activities in Trifoliate Orange

“…Likewise 28.65%, 35.15%, 27.94% and 15.01% significantly higher leaf CaM concentration was observed in C. etunicatum, D. versiformis, F. mosseae, and R. intraradices, respectively, over non-AMF-seedlings. These results are in agreement with the results of Huang et al (2014) in trifoliate orange. Strong correlation of NO and CaM with root AMF colonization suggested that, root AMF colonization could be driven through NO and CaM (Huang et al, 2014).…”

“…These results are in agreement with the results of Huang et al (2014) in trifoliate orange. Strong correlation of NO and CaM with root AMF colonization suggested that, root AMF colonization could be driven through NO and CaM (Huang et al, 2014). Leaf NO and CaM also correlated positively with root total length and number of LR in first order, indicating that AMF-induced NO and CaM as a signalling molecule are partly involved in the root development.…”

Mycorrhiza and Common Mycorrhizal Network Regulate the Production of Signal Substances in Trifoliate Orange (Poncirus trifoliata)

“…Chabaud et al (2011) indicated that exudates from AMF spores induced Ca 2+ rapid increase and Gleason et al (2006) further proved that Ca 2+ /CaM regulated calcium and calmodulin-dependent kinase (CCaMK) and induced specific gene transcription. Huang et al (2014) reported that inoculation with F. mosseae increased CaM level and promoted the resistance to drought stress in trifoliate orange. In this work, inoculation with AMF activated root CaM level in donor seedlings, and subsequent CMN colonization also promoted root CaM increase in receptor seedlings.…”