Measurement of belowground diversity of fine roots in subtropical forests based on a quantitative real-time PCR (qPCR) method

Background and aims Direct measurement of fine root diversity is very important to unveil belowground interaction, community dynamics and ecosystem functions in forests, but is limited by the effective method. This study attempted to develop specific primers for a quantitative real-time PCR (qPCR) method to determine diversity of fine roots and test whether this method could be applied in field forests. Methods We used inter-simple sequence repeat (ISSR) analyses to develop the specific primers and applied the qPCR method to determine the belowground diversity of fine roots in soil samples collected from field tree clusters containing different species. Results Specific primers were successfully developed to identify six tree species. The relative proportions of each species in known fine-root mixtures predicted by the qPCR method agreed well (r2 > 0.86, P < 0.001) with the actual relative proportions of the corresponding species. All aboveground tree species in belowground fine-root samples were detected. But tree species richness and relative proportions of belowground fine roots predicted by the qPCR method differed from aboveground trees within a given cluster. Conclusions Developing specific primers is the critical step in the qPCR method. The qPCR method can be used to determine belowground diversity of fine roots in forests.