6 research outputs found
Microbial Community Diversities and Taxa Abundances in Soils along a Seven-Year Gradient of Potato Monoculture Using High Throughput Pyrosequencing Approach
<div><p>Background</p><p>Previous studies have focused on linking soil community structure, diversity, or specific taxa to disturbances. Relatively little attention has been directed to crop monoculture soils, particularly potato monoculture. Information about microbial community changes over time between monoculture and non-monoculture treatments is lacking. Furthermore, few studies have examined microbial communities in potato monoculture soils using a high throughput pyrosequencing approach.</p><p>Methodology/Principal Findings</p><p>Soils along a seven-year gradient of potato monoculture were collected and microbial communities were characterized using high throughput pyrosequencing approach. Principal findings are as follows. First, diversity (<i>H</i><sub>Shannon</sub>) and richness (<i>S</i><sub>Chao1</sub>) indices of bacterial community, but not of fungal community, were linearly decreased over time and corresponded to a decline of soil sustainability represented by yield decline and disease incidence increase. Second, <i>Fusarium</i>, the only soilborne pathogen-associated fungal genus substantially detected, was linearly increased over time in abundance and was closely associated with yield decline. Third, <i>Fusarium</i> abundance was negatively correlated with soil organic matter (OM) and total nitrogen (TN) but positively with electrical conductivity (EC). Fourth, <i>Fusarium</i> was correlated in abundances with 6 bacterial taxa over time.</p><p>Conclusions</p><p>Soil bacterial and fungal communities exhibited differential responses to the potato monoculture. The overall soil bacterial communities were shaped by potato monoculture. <i>Fusarium</i> was the only soilborne pathogen-associated genus associated with disease incidence increase and yield decline. The changes of soil OM, TN and EC were responsible for <i>Fusarium</i> enrichment, in addition to selections by the monoculture crop. <i>Acidobacteria</i> and <i>Nitrospirae</i> were linearly decreased over time in abundance, corresponding to the decrease of OM, suggesting their similar ecophysiologial trait. Correlations between abundance of <i>Fusarium</i> with several other bacterial taxa suggested their similar behaviors in responses to potato monoculture and/or soil variables, providing insights into the ecological behaviors of these taxa in the environment.</p></div
Correlation coefficient between abundance of microbial taxa and the year of monoculture<sup>a</sup>.
a<p>RA is relative abundances. * and ** represent significance level at <0.05 and <0.01 respectively. The taxa with average relative abundance over 18 samples <0.5% and with significance level >0.05 were not shown.</p
Regressions between bacterial taxa abundances and the year of potato monoculture.
<p>Regressions between bacterial taxa abundances and the year of potato monoculture.</p
The correlations between <i>Fusarium</i> abundances and soil variables.
<p>The correlations between <i>Fusarium</i> abundances and soil variables.</p
Regressions between relative abundance of <i>Fusarium</i> and bacterial taxa.
<p>Regressions with <i>p</i> values >0.05 are not shown.</p
Overall fungal (A) and bacterial (B) communities in the soil samples along a year-gradient of potato monoculture.
<p>Pie charts show the average relative abundance over 18 samples. OTUs were assigned at the 97% identity level, based on which the <i>H</i><sub>Shannon</sub> and <i>S</i><sub>Chao1</sub> indices were calculated, which are shown by graphs. Phylogenetic lineages of bacteria were assigned by phylum/subphylum and of fungi by order or higher levels. ARA stands for average relative abundance. The “unidentified fungus” is a taxon able to be assigned to kingdom Fungi but unable to any lower taxon.</p