Abundance of arbuscular mycorrhizal fungi in relation to soil salinity around Lake Urmia in northern Iran analyzed by use of lipid biomarkers and microscopy     

Mohsen Barin  Nasser Aliasgharzad  Pål Axel Olsson  MirHassan Rasouli-Sadaghiani  Mohammad Moghddam 《Pedobiologia》2013,56(4-6):225-232

Saline soils around Lake Urmia in northern Iran constitute a stressed environment for plants and microbial communities, including arbuscular mycorrhizal (AM) fungi. Soil and root samples were collected from fields cultivated with the glycophytes Allium cepa L. and Medicago sativa L., and sites dominated by the halophyte Salicornia europaea L. Soil and root samples were analyzed for the AM fungal signature neutral lipid fatty acid (NLFA) 16:1ω5. The roots were also examined microscopically for mycorrhizal colonization. Each plant species was sampled across a salt gradient. Microscopic examination showed no AM fungal structures in the roots of S. europaea. The highest root colonization was recorded for M. sativa. The highest NLFA 16:1ω5 values were found in soil around M. sativa roots and the lowest in soil around S. europaea roots. We found evidence for stimulation of vesicle formation at moderate salinity levels in M. sativa, which is an indication of increased carbon allocation to mycorrhiza. On the other hand, we found a negative correlation between salinity and arbuscule formation in A. cepa, which may indicate a less functional symbiosis in saline soils.  相似文献   

ROOT EXUDATION AND ZINC UPTAKE BY BARLEY GENOTYPES DIFFERING IN ZN EFFICIENCY     

MirHasan Rasouli-Sadaghiani  Behzad Sadeghzadeh  Ebrahim Sepehr  Zed Rengel 《Journal of plant nutrition》2013,36(8):1120-1132

Two barley cultivars (‘Sahara’ = Zn-efficient and ‘Clipper’ = Zn-inefficient) were grown at different soil Zn fertilization (0, 0.2, 0.8, 1.6 and 3.2 mg Zn kg^?1 soil). Root exudates were collected 16 and 28 days after sowing. At Zn = 0, shoot dry matter was decreased in both genotypes, but more distinctly in ‘Clipper’. At 0.2 mg Zn kg^?1, the ‘Sahara’ shoot concentrations of Zn was 130% higher and shoot Zn content 44% greater compared with ‘Clipper’. Low-molecular-weight organic acid anions (=carboxylates) (malate, maleate, fumarate and cis-aconitate) and amino acids (alanine, valine, proline, aspartic acid and glutamic acid) were detected in root exudates, with the highest concentration at Zn = 0.2 mg kg^?1 soil. Higher concentrations of organic acid anions as well as amino acids were noted in the rhizosphere of ‘Sahara’ than ‘Clipper’. The genotypic differences in Zn acquisition from soil may be linked to differential carboxylate and amino acid composition of root exudates.  相似文献