丛枝菌根真菌繁殖体的高效扩繁

Efficient propagation of arbuscular mycorrhizal fungal propagules

摘要:

【背景】丛枝菌根(arbuscular mycorrhiza, AM)真菌能够和大多数植物形成互利共生体系，以促进植物生长、提高抗逆能力，在生产中具有重要作用，但AM真菌的繁殖技术限制了其应用。【目的】构建AM真菌的高效繁殖体系。【方法】于温室盆栽条件下，将根内根孢囊霉(Rhizophagus intraradice)接种于由3种寄主植物高粱(Sorghum bicolor)、玉米(Zea mays)、红三叶草(Trifolium repens)与5种培养基质(沸石、河砂、草炭、珍珠岩和蛭石)构建的4种繁殖体系中进行培养。研究不同繁殖体系对根内根孢囊霉侵染程度、产孢量的影响；然后利用高粱接种扩繁的菌剂进行AM真菌侵染能力的测定以验证其扩繁效果；最后基于筛选出的最优扩繁条件探讨对其他种类AM真菌摩西斗管囊霉(Funneliformis mosseae)、幼套近明球囊霉(Clariodeoglous etunicatum)、地表多样孢囊霉(Diversispora versiformis)和脆无梗囊霉(Acaulospora delicate)的扩繁效果。【结果】基质为河砂+蛭石+草炭(体积比为1:4:1)，寄主植物为玉米+红三叶草处理的根内根孢囊霉产孢量最高，达到 1 912个/g-基质且接种高粱后表现出较好的侵染潜力，同时显著提高了高粱的地上部生物量。此外，利用该组合扩繁其他种类AM真菌，发现孢子数均得到了显著的提高，扩繁后摩西斗管囊霉、幼套近明球囊霉、地表多样孢囊霉和脆无梗囊霉的孢子数较扩繁前分别增加了6.24、2.92、35.18和4.18倍。【结论】以玉米+红三叶草为寄主植物，以河砂+蛭石+草炭(1:4:1)为基质，即通气孔隙为3.57%、持水孔隙为48.19%、容重为1.03 g/cm³、电导率为152.5 μS/cm、pH值为5.61、速效磷为5.6 mg/kg、碱解氮为80 mg/kg、速效钾为449.8 mg/kg、有机质为56.11 g/kg的条件有助于根内根孢囊霉达到最佳的扩繁效果，同时对其他AM真菌扩繁效果也相对较好，能够达到高效扩繁AM真菌繁殖体的目的。

关键词:丛枝菌根真菌;基质;寄主植物;孢子密度

Abstract:

[Background] Arbuscular mycorrhizal (AM) fungi can form mutualistic symbiosis with most plants to promote the growth and enhance the stress resistance of plants, playing an important role in production. However, the immature propagation technology limits the application of AM fungi. [Objective] To establish an efficient propagation system of AM fungi. [Methods] A pot experiment was conducted. Specifically, Rhizophagus intraradice was inoculated into four propagation systems constructed with three host plants (Sorghum bicolor, Zea mays, and Trifolium repens) and five substrates (zeolite, river sand, peat, perlite, and vermiculite) for culture. The effects of different propagation systems on the infection and sporulation of R. intraradice were studied. Then, we measured the infection ability of AM fungi by inoculating S. bicolor with propagation inoculum to verify the propagation effect. Finally, the optimal propagation conditions were employed to explore the propagation of other species of AM fungi: Funneliformis mosseae, Clariodeoglous etunicatum, Diversispora versiformis, and Acaulospora delicate. [Results] The propagation system with river sand+vermiculite+peat (1:4:1) as the substrate and Z. mays+T. repens, R. intraradice as the host plants had the highest spore production of 1 912 spores/g-dry substrate. Moreover, the AM fungi propagated with this system showed better infection potential and remarkably increased the aboveground biomass of S. bicolor. In addition, the propagation with this system increased the sporulation of F. mosseae, C. etunicatum, D. versiformis, and A. delicate by 6.24, 2.92, 35.18, and 4.18 times, respectively, compared with that before propagation. [Conclusion] The propagation system with Z. mays+T. repens as the host plants and river sand+vermiculite+peat (1:4:1) as the substrate had the optimum results. This system had the aeration porosity of 3.57%, the water-holding porosity of 48.19%, the bulk density of 1.03 g/cm³, the electrical conductivity of 152.5 μS/cm, pH 5.61, the available phosphorus of 5.6 mg/kg, the available nitrogen of 80 mg/kg, the available potassium of 449.8 mg/kg, and the organic matter of 56.11 g/kg, which are conducive to the efficient propagation R. intraradice and other AM fungi.

Key words:arbuscular mycorrhizal fungi;substrate;host plant;spore density