Quantification of Nitrogen Reductase and Nitrite Reductase Genes in Soil of Thinned and Clear-Cut Douglas-Fir Stands by Using Real-Time PCR

Abstract

The abundance of nifH, nirS, and nirK gene fragments involved in nitrogen (N) fixation and denitrification in thinned second-growth Douglas-fir (Pseudotsuga menziesii subsp. menziesii [Mirb.] Franco) forest soil was investigated by using quantitative real-time PCR. Prokaryotic N cycling is an important aspect of N availability in forest soil. The abundance of universal nifH, Azotobacter sp.-specific nifH (nifH-g1), nirS, and nirK gene fragments in unthinned control and 30, 90, and 100% thinning treatments were compared at two long-term research sites on Vancouver Island, Canada. The soil was analyzed for organic matter (OM), total carbon (C), total N, NH 4 -N, NO 3 -N, and phosphorus (P). The soil horizon accounted for the greatest variation in nutrient status, followed by the site location. The 30% thinning treatment was associated with significantly greater nifH-g1 abundance than the control treatment in one site; at the same site, nirS in the mineral soil horizon was significantly reduced by thinning. The abundance of nirS genes significantly correlated with the abundance of nirK genes. In addition, significant correlations were observed between nifH-g1 abundance and C and N in the organic horizon and between nirS and nirK and N in the mineral horizon. Overall, no clear influence of tree thinning on nifH, nirS, and nirK was observed. However, soil OM, C, and N were found to significantly influence N-cycling gene abundance.

Differential distribution and abundance of diazotrophic bacterial communities across different soil niches using a gene-targeted clone library approach

“…(). The nifH genes have been reported to be present in good numbers in various terrestrial habitats (Levy‐Booth & Winder, ; Xiao et al ., ). The saline soils are devoid of vegetation, and therefore lower cycling of organic matter is expected, which allows diazotrophs to flourish.…”

Influence of carbon amendments on soil denitrifier abundance in soil microcosms

“…A positive relationship between amount of organic C and abundance of some functional groups of denitrifiers was observed (Barta et al, 2010;Chen et al, 2010;Dandie et al, 2008;Kandeler et al, 2006;Levy-Booth and Winder, 2010). It was reported that the source of organic C changed the composition of denitrifier communities: i.e.…”

Application of targeted metagenomics to explore abundance and diversity of CO2-fixing bacterial community using cbbL gene from the rhizosphere of Arachis hypogaea

“…The qPCR methods were used to determine the abundance of amoA, cbbL, nifH, etc. genes from marine environments and agriculture soils (He et al, 2007;Levy-Booth and Winder, 2010;Selesi et al, 2007).…”