铜胁迫条件下AMF对海州香薷光合色素含量、抗氧化能力和膜脂过氧化的影响

以盆栽海州香薷为研究对象,模拟Cu胁迫条件下,接种丛枝菌根真菌(AMF)对海州香薷叶片光合色素含量、抗氧化酶活性、抗氧化剂含量、膜脂过氧化程度的影响。结果表明:(1)与对照相比,Cu胁迫使海州香薷叶片叶绿素a(Chl a)、叶绿素b(Chl b)、总叶绿素(Chl(a+b))、类胡萝卜素(Car)含量以及叶绿素a/b(Chl a/b)均显著降低,抗氧化酶活性和抗氧化剂含量也显著下降,质膜相对透性(MRP)和丙二醛(MDA)含量显著增大。(2)与Cu胁迫相比,Cu胁迫下接种AMF可使海州香薷叶片叶绿素含量显著增加;超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)活性显著提高;还原型谷胱甘肽(GSH)、抗坏血酸(As A)含量显著增加;MDA含量、MRP显著下降。总之,接种AMF可提高Cu胁迫下海州香薷叶片光合色素含量和抗氧化能力,降低膜脂过氧化水平,从而缓解Cu胁迫对植株造成的伤害,增强海州香薷对Cu胁迫的适应性,提高了植株的生物量。

Effects of arbuscular mycorrhizal fungi inoculation on the photosynthetic pigment contents, anti-oxidation capacity and membrane lipid peroxidation of Elsholtzia splendens leaves under copper stress

Arbuscular mycorrhizal fungi (AMF), which engage in a mutualistic symbiosis with the roots of most plant species, have been well studied for their ability to alleviate heavy metal stress, including that of copper (Cu), in plants. Most mycorrhizal studies have focused on AMF effects on host plant nutrient uptake. However, few studies have investigated plant physiological responses during plant-microbe interactions, which are necessary to understand the efficiency of the phytoremediation of heavy metal pollution. Elsholtzia splendens, a widely distributed Cu-tolerant plant, is usually found in the Cu mining areas of southern China and is colonized by symbiotic AMF. This study examines the effects of AMF on the physiological responses of E. splendens leaves under Cu stress. A controlled pot experiment was performed to investigate the effects of AMF inoculations and Cu additions on E. splendens leaves'' photosynthetic pigment contents, anti-oxidation enzymatic activities, antioxidant contents and lipid peroxidation. The plants, which were grown on a mixture of sterilized soil and sand, were inoculated with AMF (non-inoculated plants were controls), with or without the addition of Cu (1000 mg/kg and 0 mg/kg, respectively). The results showed that AMF could well colonize the roots of E. splendens under both Cu treatments. The plant root biomass, stem biomass, leaf biomass, inflorescence biomass and total biomass of E. splendens under Cu stress were lower than in the control. Inoculations with AMF significantly increased the plant root biomass, stem biomass, leaf biomass, inflorescence biomass and total biomass of E. splendens under Cu stress by 36.1%, 138.9%, 47.3%, 68.4% and 79.7%, respectively, and significantly decreased the root shoot ratio by 26.3%, indicating an alleviating effect of Cu inhibition on E. splendens growth. Compared with the control, the chlorophyll a (Chl a) and chlorophyll b (Chl b) contents, Chl a+b content [Chl (a+b)], carotenoid content and chlorophyll a/b ratio (Chl a/b) under Cu stress significantly decreased by 56.2%, 52.6%, 55.1%, 49.8% and 7.5%, respectively. Additionally, the superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), catalase (CAT), glutathione (GSH) and ascorbic acid (AsA) contents in the leaves of E. splendens under Cu stress significantly decreased by 44.8%, 45.0%, 61.0%, 43.7%, 49.2% and 31.1%, respectively, while the membrane relative permeability (MRP) and malondialdehyde (MDA) contents significantly increased by 61.5% and 106.4%, respectively. With the Cu addition, the AMF inoculation significantly increased the Chl a, Chl b and Chl (a+b) contents in E. splendens leaves by 36.7%, 30.6% and 34.8%, respectively, and the GSH and AsA contents by 55.1% and 29.6%, respectively. It also enhanced the SOD and APX activities by 33.7% and 66.1%, respectively, while it reduced the MRP and MDA contents by 18.0% and 20.2%, respectively. In conclusion, AMF inoculations could effectively alleviate the damage of Cu stress on E. splendens by increasing the photosynthetic pigment contents and the antioxidant capacities, while decreasing the lipid peroxidation of cell membranes and the relative conductivity, which might be important for Cu stress adaptation and the improved productivity of E. splendens.