菲和芘胁迫下AMF和PGPR对高羊茅生理生态的响应

旨在探究菲和芘胁迫下丛枝菌根真菌(AMF)与根围促生细菌(PGPR)对高羊茅生理生态的响应。以菲和芘1∶1混合处理浓度各0、50、100和150mg·kg^-1下对高羊茅接种AMF变形球囊霉(Gv)、PGPR荧光假单胞菌(Ps2-6)、Gv+Ps2-6和不接种对照共16个处理。结果表明,AMF、PGPR或AMF+PGPR处理均显著增加高羊茅生物量和菌根侵染率,增强植物光合作用,提高叶绿素含量,显著提高植物体内生理活性。在土壤中菲和芘100mg·kg^-1水平下,与对照相比,双接种Gv+Ps2-6处理的高羊茅叶片叶绿素a、b和总叶绿素含量分别提高57.7%、41.7%和51.8%;净光合速率(Pn)、蒸腾速率(Tr)、胞间CO2浓度(Ci)和气孔导度(Gs)分别增加70.6%、100.0%、4.5%和78.6%;最大光化学效率(Fv/Fm)和PSⅡ潜在活性(Fv/Fo)分别提高2.2%和8.8%;超氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性、可溶性糖和脯氨酸含量分别是对照的1.6、1.5、2.3和2.7倍,丙二醛含量比对照下降46.0%;高羊茅株高和地上鲜重分别比对照增加63.0%和69.6%;接种PGPR处理能够增加AMF侵染率以及菌根依赖性。供试条件下,双接种Gv+Ps2-6处理增加高羊茅叶绿素含量和抗氧化能力,增强光合作用能力,降低膜脂过氧化水平,促进植物生长的作用最为显著。

Responses of AMF and PGPR to Festuca elata under phenanthrene and pyrene stress

The purpose of the present study was to evaluate mechanisms (and their efficiency) for degradation of residues of phenanthrene and pyrene by arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR). A total of 16 treatments were designed involving Festuca elata, with or without inoculation with AMF Glomus versiforme (Gv), PGPR Pseudomonas fluorescens (Ps2-6), or Gv+Ps2-6, and grown soil with 0 (Control), 50, 100 or 150 mg·kg^-1 added polycyclic aromatic hydrocarbons (PAHs) (phenanthrene∶pyrene=1∶1 in weight). The results showed that inoculation with AMF, PGPR or AMF+PGPR significantly increased the biomass and mycorrhizal infection rate of tall fescue, enhanced photosynthesis and chlorophyll content of plants, and significantly increased the physiological activity of plants. At 100 mg·kg^-1 phenanthrene and pyrene, the chlorophyll a, b and total chlorophyll content in the leaves of tall fescue were increased by 57.7%, 41.7% and 51.8%, respectively, compared with the Control, and the net photosynthetic rate (P_n), transpiration rate (T_r), intercellular CO₂ concentration (C_i) and gas pore conductivity (G_s) were increased by 70.6%, 100.0%, 4.5% and 78.6%, respectively; the maximum photochemical efficiency (F_v/F_m) and PSⅡ potential activity (F_v/F_o) were increased by 2.2% and 8.8%, respectively. The activities of superoxide dismutase (SOD), catalase (CAT), soluble sugar and proline were, respectively, 1.6, 1.5, 2.3 and 2.7 times those of the Control; the malondialdehyde content was decreased by 46.0%, and the height and fresh weight were increased by 63.0% and 69.6%. Inoculation with PGPR increased AMF infection rate and mycorrhizal dependency. Under the test conditions, double inoculation with a Gv+Ps2-6 treatment increased the content of photosynthetic pigments and antioxidant capacity of Festuca elata, enhanced photosynthetic capacity, reduced the level of membrane lipid peroxidation, and significantly promoted plant growth.