Carvalho Luís M, Correia Patrícia M, Martins-Loução M Amélia
Departamento de Biologia Vegetal, Faculdade de Ciências de Lisboa, Centro de Ecologia e Biologia Vegetal, Bloco C2, Campo Grande, 1749-016, Lisbon, Portugal.
Mycorrhiza. 2004 Jul;14(3):165-70. doi: 10.1007/s00572-003-0247-4. Epub 2003 Jun 13.
The tolerance of indigenous arbuscular mycorrhizal fungi (AMF) to stressful soil conditions and the relative contribution of spores of these fungi to plant colonization were examined in a Portuguese salt marsh. Glomus geosporum is dominant in this salt marsh. Using tetrazolium as a vital stain, a high proportion of field-collected spores were found to be metabolically active at all sampling dates. Spore germination tests showed that salt marsh spores were not affected by increasing levels of salinity, in contrast to two non-marsh spore isolates, and had a significantly higher ability to germinate under increased levels of salinity (20 per thousand) than in the absence of or at low salinity (10 per thousand). Germination of salt marsh spores was not affected by soil water levels above field capacity, in contrast to one of the two non-marsh spore isolates. For the evaluation of infectivity, a bioassay was established with undisturbed soil cores (containing all types of AM fungal propagules) and soil cores containing only spores as AM fungal propagules. Different types of propagules were able to initiate and to expand the root colonization of a native plant species, but spores were slower than mycelium and/or root fragments in colonizing host roots. The AM fungal adaptation shown by this study may explain the maintenance of AMF in salt marshes.
在葡萄牙的一个盐沼中，研究了本土丛枝菌根真菌（AMF）对胁迫土壤条件的耐受性以及这些真菌的孢子对植物定殖的相对贡献。格氏球囊霉在这个盐沼中占主导地位。使用四唑作为活体染色剂，发现在所有采样日期，野外采集的孢子中有很大比例具有代谢活性。孢子萌发试验表明，与两种非盐沼孢子分离株相比，盐沼孢子不受盐度增加的影响，并且在盐度增加（20‰）时的萌发能力明显高于无盐或低盐度（10‰）时。与两种非盐沼孢子分离株之一不同，盐沼孢子的萌发不受高于田间持水量的土壤水位的影响。为了评估侵染性，建立了一种生物测定法，使用未扰动的土壤芯（包含所有类型的AM真菌繁殖体）和仅含有孢子作为AM真菌繁殖体的土壤芯。不同类型的繁殖体都能够启动并扩展一种本地植物物种的根部定殖，但孢子在定殖宿主根系方面比菌丝体和/或根片段要慢。本研究显示的AM真菌适应性可能解释了盐沼中AMF的维持。
