College of Horticulture and Gardening/Institute of Root Biology, Yangtze University Jingzhou, China.
National Research Centre for Citrus Nagpur, India.
Front Microbiol. 2014 Dec 5;5:682. doi: 10.3389/fmicb.2014.00682. eCollection 2014.
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 ([Formula: see text]), 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 [Formula: see text] 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 [Formula: see text] 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.
枳[Poncirus trifoliata (L) Raf.]被认为高度依赖丛枝菌根（AM），通过一系列信号转导，表现为各种生理反应，从而促进生长。本研究旨在评估 AM 真菌（Funneliformis mosseae）对生长、抗氧化酶（过氧化氢酶，CAT；超氧化物歧化酶，SOD）活性、叶片相对含水量（RWC）、钙调蛋白（CaM）、超氧阴离子（[Formula: see text]）和叶片中过氧化氢（H2O2）浓度的影响，这些植物在充分供水（WW）和干旱胁迫（DS）条件下暴露。DS 处理 58 天后，AM 定殖率比 WW 处理显著降低 60%。与非 AM 幼苗相比，无论土壤水分状况如何，AM 幼苗的地上形态特性（株高、茎直径和叶片数）、生物量生产（地上部和根鲜重）和叶片 RWC 均显著较高。AM 接种显著增加了 CaM 和可溶性蛋白浓度以及 CAT 活性，而在 WW 和 DS 条件下，[Formula: see text]和 H2O2浓度显著降低。在 DS 条件下，与非 AM 幼苗相比，AM 幼苗的 Cu/Zn-SOD 和 Mn-SOD 活性也显著较高，但在 WW 条件下则不然，这是基于相关性研究，AM 植物中较高的 CaM 水平引发的。此外，Cu/Zn-SOD 和 Mn-SOD 活性与[Formula: see text]和 H2O2浓度呈负相关，表明在 DS 下，CaM 介导的 SOD 对 ROS 的清除能力。我们的结果表明，AM 接种提高了叶片中 CaM 的合成，并上调了抗氧化酶的活性，从而在 DS 条件下通过降低 ROS 积累来修复植物可能受到的氧化损伤。
