Arbuscular mycorrhizal fungi improve the antioxidant capacity of tea (Camellia sinensis) seedlings under drought stress

Chun-Yan LIU,Kamil KUČA,Tian-Yuan YANG,Qiang-Sheng WU,Yu-Juan WANG

doi:10.15835/nbha48412066

Abstract

A pot experiment was carried out to evaluate the response of leaf antioxidant enzyme systems to inoculation with arbuscular mycorrhizal fungus (AMF) Clariodeoglomus etunicatum in tea (Camellia sinensis cv. ‘Fuding Dabaicha’) seedlings under drought stress (DS). Root AMF colonization was significantly decreased after an eight-week soil drought treatment. Plant growth performance (plant height, stem diameter, leaf number and root biomass), leaf relative water content, and leaf water potential were notably decreased under DS conditions, whereas these variables exhibited significantly higher responses in mycorrhizal seedlings than in non-mycorrhizal seedlings. The DS treatment markedly increased leaf superoxide anion concentration but did not affect malondialdehyde content, whereas both were reasonably decreased by AMF colonization regardless of water status. The seedlings colonized by AMF showed substantially higher antioxidant enzyme activities including superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase, and ascorbate peroxidase than the non-AMF colonized seedlings under both well-watered and DS conditions. DS markedly upregulated the relative expression of CsSOD in both AMF and non-AMF seedlings and the relative expression of CsCAT in AMF seedlings. Meanwhile, AMF-colonized seedlings represent markedly higher relative expressions of CsSOD and CsCAT than non-AMF seedlings, irrespective of water status. It concludes that mycorrhizal tea plants had higher antioxidant enzyme activity and corresponding gene expression under DS, indicating a stronger ability to alleviate the oxidative damage of drought.

Highlights

The present study showed a dramatic reduction in root arbuscular mycorrhizal fungus (AMF) colonization of tea plants under drought stress (DS) conditions as compared with tea plants under WW conditions, which is consistent with the results by Amiri et al (2015), Tuo et al (2017), and Zhang et al (2020), who observed a significant decrease of mycorrhizal colonization in citrus, geranium, and white clover under water deficit conditions
The RNA-sequence analysis further confirmed that AMF coped with oxidative stress via the induction of multiple metabolic processes, including antioxidant enzyme genes (Venice et al, 2016)
The results of this study showed that AMF treatment markedly up-regulated the expressions of CsSOD and CsCAT in leaves under both WW and DS conditions

Summary

Introduction

Kuntze) is one of the oldest and most popular caffeinated nonalcoholic beverages in the world, consumed by more than 3 billion people in 160 countries (Ding et al, 2017). Tea plants are rain-fed, evergreen perennial crops, mainly grown in tropical and subtropical regions of Asia (Wang et al, 2017). Excessive soil moisture and water deficiency both can cause water stress (Gupta et al, 2012). Received in revised form: 11 Nov 2020.

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Discussion

Conclusion