Impact of tree species on barley rhizosphere-associated fungi in an agroforestry ecosystem as revealed by 18S rDNA PCR-DGGE

Abstract

Agroforestry systems have been considered a form of sustainable land use. Woody species in agroforestry systems can improve soil physicochemical properties by supplying leaf or stem litter. However, little is known about fungal community structure and diversity in agroforestry systems. In the present study, the culture-independent 18S rDNA-based polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) method was used to investigate fungal community structure in rhizosphere and bulk soil in Populus euramevicana-barley and Taxodium distichum-barley agroforestry systems. DGGE profiling and cluster analysis revealed that the fungal community structure in the rhizosphere was more complex than that of bulk soil. Our results also indicated that the rhizosphere fungal community in barley was less affected by T. distichum than by P. euramevicana. In addition, an increase in the relative abundance of certain rhizosphere fungal populations was detected in this agroforestry system. Sequencing of prominent DGGE bands revealed an increase in the rhizosphere of a fungal species belonging to the genera Chaetomium, which includes potential biocontrol agents. A rare cellulolytic fungus, Acremonium alcalophilum, was found in the bulk soil from P. euramevicana and barley grown under P. euramevicana. Taken together, our findings may provide new insights into agroforestry practices.