Arbuscular Mycorrhiza Improves Leaf Food Quality of Tea Plants

Abstract

Tea (Camellia sinensis) plants inhabit arbuscular mycorrhizal fungi (AMF) in rhizosphere, whereas it is not clear whether AMF improves leaf food quality of tea plants. A potted study was conducted to determine effects of Claroideoglomus etunicatum, Diversispora spurca, D. versiformis and a mixture of the three AMF species on leaf sugar, amino acid, soluble protein, tea polyphenol, catechuic acid, and flavonoid contents of Camellia sinensis ‘Fuding Dabaicha’ seedlings. After 12 weeks of AMF inoculation, mycorrhizal plants recorded significantly higher shoot biomass and total leaf area, whilst the effect was ranked as C. etunicatum > D. spurca > mixed-AMF > D. versiformis in the decreasing order. AMF treatments significantly increased leaf total amino acid concentrations, accompanied with up-regulation of amino acid synthetic enzymes genes glutamine synthetase (CsGS), glutamate synthase (CsGOGAT) and glutamate dehydrogenase (CsGDH). Leaf glucose, sucrose, total soluble protein, tea polyphenol, catechuic acid, and flavonoid contents were significantly higher in AMF- than in non-AMF-inoculated plants. In addition, mycorrhizal inoculation notably up-regulated the expression level of leaf 3-hydroxy-3-methylglutaryl coenzyme gene (CsHMGR), ascorbate peroxidase gene (CsAPX), and tea caffeine synthase 1 gene (CsTCS1). These results implied that AMF inoculation had positive effects on leaf food quality partly by means of up-regulation of relevant gene expression in ‘Fuding Dabaicha’ seedlings.