荒漠植物根际AM真菌的空间分布和定殖(英文)

SPATIAL DISTRIBUTION AND COLONIZATION OF ARBUSCULAR MYCORRHIZAL FUNGI IN THE RHIZOSPHERE OF DESERT SHRUBS

通过分析以色列荒漠地区Zygophyllumdumosum ,Hammadascoparia ,Artemisiaherba_alba和Atriplexhalimus等4种灌木根际AM真菌的空间分布和定殖程度 ,研究了AM真菌分布和定殖与植物种类和土壤因子间的相关性。样品分别从 0～ 10cm ,10～ 2 0cm ,2 0～ 30cm ,30～ 40cm和 40～ 5 0cm等 5个土层中采取 ,土样过 2mm筛。收集的根样切成 1cm根段 ,经染色后 ,根据感染长度确定AM真菌不同结构的定殖率 ;用湿筛倾析法和蔗糖梯度离心法从土样中分离孢子 ;土壤湿度 ,有机质和总可溶性氮含量按文中描述的方法测定。结果表明 ,AM真菌的空间分布和定殖模式与植物种类密切相关。在Artemisiaherba_alba和Atriplexhalimus根际 ,AM真菌定殖率和孢子密度高 ;而在Zygo phyllumdumosum和Hammadascoparia根际 ,AM真菌定殖率和孢子密度较低。土壤采样深度对孢子密度和泡囊、丛枝和总的定殖率有显著影响 ,最高定殖率出现在 2 0～ 30cm土层 ,而最大孢子密度则发生在 10～ 2 0cm土层。孢子密度与泡囊定殖率呈正相关 ,而与丛枝定殖率呈负相关。土壤总可溶性氮对孢子密度有显著的负效应 ,土壤湿度和有机质含量同AM真菌的定殖和孢子密度没有显著的相关性。在评估荒漠生态系统和不同植物形成菌根的能力时 ,AM真菌的孢子密度。

This study assesses and compares the response of AM fungi to plant species and its abiotic environment by analysing soil samples collected in a field study at Negev Desert of Israel. Soil samples in the rhizosphere of Zygophyllum dumosum, Hammada scoparia, Artemesia herba-alba and Atriplex halimus were collected in 4 replicates and divided a depth of 50 cm into 5 sections, i.e. 0-10, 10-20, 20-30, 30-40 and 40-50 cm in the rhizosphere of each plant. Before processing, soil samples were sieved (2 mm mesh size) and root segments were collected from each sample. Subsamples from each replicate were used for soil moisture, organic matter and total soluble N determination. The total AM fungal spore number was determined by wet sieving (45-500 μm) and sucrose density centrifugation, and counting under a stereoscopic microscope at ×40. Root samples were cut into 1 cm long pieces, then cleared with 10% (w/v) KOH and stained with 0.05% (v/v) trypan blue in lactophenol. Colonization assessment was conducted on each sample by the glass slide method on which 50 randomly selected 1 cm root segment units were determined microscopically. The results showed that different plant species significantly affected AM fungal colonization and spore density. Higher spore density tended to be correlated with higher AM fungal colonization in the rhizosphere of A. herba-alba and A. halimus, and vice versa for Z. dumosum and H. scoparia. At the tested soil depths, the highest AM fungal colonization occurring at the 20-30 cm section did not coincide with higher spore density existing at the 10-20 cm section. Sampling depth of soil had a significant effect on spore density and the percent colonization of total, vesicle and arbuscule. Spore density had a positive correlation with vesicular colonization and a negative correlation with arbuscular colonization. Soil total soluble N exhibited a negative effect on spore density. Soil moisture and organic matter content did not exhibit a significant correlation with AM fungal colonization or spore density. The distribution and colonization of AM fungi, especially spore density, vesicular and arbuscular colonization are a useful indicator for monitoring the change of desert soil ecosystem and evaluating the ability of forming mycorrhizae of different plant species.