Alleviation of Mycorrhiza to Magnesium Deficiency in Trifoliate Orange: Changes in Physiological Activity

Fei Zhang,Changxu Song,Qiangsheng Wu,Peng Du

doi:10.9755/ejfa.2015-05-240

Fei Zhang, Changxu Song + Show 2 more

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https://doi.org/10.9755/ejfa.2015-05-240

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Abstract

Deficiency of magnesium (Mg) is quite common in citrus trees and often results in leaf chlorosis. In this study, five-leaf-old trifoliate orange (Poncirus trifoliata) seedlings were grown in sands and inoculated with an arbuscular mycorrhizal fungus (AMF), Funneliformis mosseae. After 8 days of transplanting, the seedlings were subjected to Mg-deficient (0.2 mM Mg2+) and Mg-sufficient (2 mM Mg2+) treatments for 92 days. Growth performance, chlorophyll concentration, soluble protein concentration, and antioxidant enzyme activities were determined. The results showed that root AMF colonization was significantly higher under Mg-deficiency than under Mg-sufficiency. AMF inoculation significantly increased leaf, stem, root, and total (leaf+ stem+root) biomass production and third-order lateral root number than non-AMF treatment under Mg-deficient and Mg-sufficient conditions. Compared with Mg-sufficiency, Mg-deficiency considerably reduced chlorophyll a and chlorophyll a+b concentration, whereas AMF inoculation significantly increased chlorophyll a and chlorophyll a+b concentration, representing the alleviation of leaf chlorosis by mycorrhization. The AMF seedlings presented significantly higher concentration of soluble protein concentration in leaf and root and activity of superoxide dismutase and catalase in root than the non-AMF seedlings exposed to Mg-deficient and Mg-sufficient, respectively. It concludes that AMF inoculation had positive effects on growth performance and physiological activities of trifoliate orange under Mg deficient condition, thus, possibly enhancing tolerance to Mg deficiency.

Highlights

Magnesium (Mg) is needed for many physiological processes in plants, chlorophyll production, because it is an essential constituent of chlorophyll
The objective of the present study was to evaluate the effects of arbuscular mycorrhizal fungus (AMF) inoculation on plant biomass, chlorophyll concentration, soluble protein concentration, and antioxidant enzymatic activities in trifoliate orange [Poncirus trifoliata (L.) Raf.] under Mg deficient and Mg sufficient conditions
Root AM colonization In the present study, root mycorrhizal colonization was not found in the non-AMF inoculated trifoliate orange seedlings, but varied from 60.03 to 88.25% in the AMF seedlings (Table 1 and Fig. 1a–1b)

Summary

Introduction

Magnesium (Mg) is needed for many physiological processes in plants, chlorophyll production, because it is an essential constituent of chlorophyll. Enhancing tolerance of citrus trees to Mg deficiency in soil is an increasing gap in citrus production. Arbuscular mycorrhizal fungi (AMF), one of the important soil beneficial fungi, can form symbiotic associations with the roots of ~80% of plants in terrestrial ecosystems, including citrus plants (Fidelibus et al, 2001; Wu et al, 2013a; Ortas and Ustuner, 2014). In Citrus tangerina plants, inoculation with Diversispora versiformis significantly increased leaf Mg level under well-watered and drought stress conditions (Wu and Xia, 2006). AMF inoculation considerably enhanced antioxidant enzyme activities in citrus plants exposed to salt stress, temperature stress, and waterlogging stress

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