Mycorrhiza improves cold tolerance of Satsuma orange by inducing antioxidant enzyme gene expression

[摘要] A potted experiment was carried out to study the effect of an arbuscular mycorrhizal fungus (Diversisporaversiformis) and arbuscular mycorrhizal like fungus (Piriformospora indica) on antioxidant enzyme defense system ofSatsuma orange (Citrus sinensis cv. Oita 4) grafted on Poncirus trifoliata under favourable temperature (25°C) andcold temperature (0°C) for 12 h. Such short-term treatment of cold temperature did not cause any significant changein root fungal colonization and spore density in soil. Under cold stress, D. versiformis inoculation did not change theactivity of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) in leaves and roots, whereas P. indicainoculation significantly increased the activity of CAT in roots and POD in leaves only. In addition, inoculation oftwo mycorrhizal fungi under cold stress significantly increased the relative expression levels of PtPOD and PtF-SODin leaves, P. indica up-regulated the expression levels of PtCu/Zn-SOD in leaves, and D. versiformis also induced theexpression levels of PtMn-SOD and PtCAT1 in leaves. In addition, inoculated Oita 4 trees maintained significantlylower hydrogen peroxide levels and malondialdehyde contents in leaves and roots under cold temperature, suggestinglower oxidative damage. Therefore, we concluded that arbuscular mycorrhizal fungi (especially P. indica) mainlyinduced the expression of antioxidant enzyme genes, depending on the fungal species, and thus mitigated oxidativedamage for higher cold resistance in inoculated plants.

[学科分类] 仪器

[关键词] Antioxidant defense system;Citrus;Cold stress;Mycorrhiza;Oxidative burst