PEG-6000胁迫下3种外生菌根真菌的生长特性

为了解不同外生菌根真菌的抗旱能力及机制，筛选具有较强抗旱性的优良菌株。选取琥珀乳牛肝菌(sp)、粘盖乳牛肝菌(sb)、橙黄硬皮马勃(sc)3种外生菌根真菌，采用液体培养和固体培养2种方式，利用PEG-6000模拟干旱条件，研究不同干旱胁迫程度对3种外生菌根真菌生长及生理变化的影响。结果表明，在不同PEG-6000浓度下,sb菌丝生长速率一致，sp在0~21 d的菌丝生长速率较高，sc则在14~28 d才呈现速生期；轻度干旱胁迫（PEG-6000浓度为10％~20％）有利于sb和sp生物量的积累，增加sb对H⁺的分泌，并提高sb的SOD活性，降低sb的MDA含量，而sc的生长则受到PEG-6000的抑制；在PEG-6000处理下，3种外生菌根真菌的菌丝形态出现了不同程度损伤，随PEG-6000浓度升高菌丝形态损伤进一步加重，但sb菌丝形态结构完整度高于sp与sc。因此，轻度干旱胁迫利于sb的生长，3种外生菌根真菌抗旱性强弱为:sb>sp>sc。本研究结果可为外生菌根真菌抗旱机制的深入研究及抗旱菌种的筛选提供参考。

Growth Characteristics of Three Ectomycorrhizal Fungi under PEG-6000 Stress

In order to understand the drought resistance capabilities and mechanism of different ectomycorrhizal fungi to screen out drought resistance species,three types of ectomycorrhizal fungi were used as research subjects: Sinoboletus placidus (sp),Suillus bovinus (sb),and Sclerderma citrinum (sc),which were cultured in liquid and solid media under drought conditions simulated by PEG-6000 to examine the effects of different drought levels on the growth and physiological changes of the fungi investigated.The results showed that under different concentrations of PEG-6000,the growth rate of sb mycelium was consistent,while for sp,it was higher during 0-21 d,for sc,the rapid growth period was between 14-28 d.Mild drought stress (PEG-6000 concentrations were between 10% and 20%) was conducive to the accumulation of sb and sp biomass,which would increase the secretion of H⁺ and the SOD activity of sb,reduce the MDA content of sb,while the growth of sc was inhibited by PEG-6000.The mycelial morphology of three fungi showed different degrees of damage under the PEG-6000 stress,and with the increase of PEG-6000 concentration,the damage was further aggravated.Comparatively,the morphological structure of sb mycelial was more complete than sp and sc.It was concluded that mild drought stress was conducive to the growth of sb.The drought resistance of the three ectomycorrhizal fungi was in the order of sb>sp>sc.The results of this study would provide a reference for the in-depth study of drought-resistant mechanisms of ectomycorrhizal fungi and the selection of drought tolerant fungi.