Dataset Information

Rhizosphere Bacterial Community Response to Continuous Cropping of Tibetan Barley.

ABSTRACT: Long-term continuous cropping influences the nutrient of soil and microbiome of the rhizosphere, resulting in the yield decrease of crops. Tibetan barley is a dominant cereal crop cultivated at high altitudes in Tibet. Its growth and yield are negatively affected by continuous cropping; however, the response of the rhizosphere microbial community to continuous cropping remains poorly understood. To address this question, we investigated the bacterial community structure and conducted predictive functional profiling on rhizosphere soil from Tibetan barley monocropped for 2-6 years. The results revealed that long-term continuous cropping markedly decreased total nitrogen and available nitrogen in rhizosphere soil. Illumina high-throughput sequencing of 16S rRNA genes indicated that the bacterial community was altered by continuous cropping; operational taxonomic units (OTUs), Shannon index, and Faith Phylogenetic Diversity decreased with increasing monocropping duration. Relative abundances of family Pseudomonadaceae, Cytophagaceae, and Nocardioidaceae were significantly increased, while those of Chitinophagaceae and Sphingomonadaceae were significantly decreased (all p < 0.05). Besides, continuous cropping significantly increased the abundance of bacteria associated with chemoheterotrophy, aromatic compound degradation, and nitrate reduction (p < 0.05). Generalized boosted regression model analysis indicated that total nitrogen was the most important contributor to the bacterial community diversity, indicating their roles in shaping the rhizosphere bacterial community during continuous cropping. Overall, continuous cropping had a significant impact on the structure of bacterial communities in rhizosphere soil of Tibetan barley, and these results will improve our understanding of soil bacterial community regulation and soil health maintenance in Tibetan barley farm systems.

SUBMITTER: Yao Y

PROVIDER: S-EPMC7734106 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Rhizosphere Bacterial Community Response to Continuous Cropping of Tibetan Barley.

Yao Youhua Y Yao Xiaohua X An Likun L Bai Yixiong Y Xie Deqing D Wu Kunlun K

Frontiers in microbiology 20201130

Long-term continuous cropping influences the nutrient of soil and microbiome of the rhizosphere, resulting in the yield decrease of crops. Tibetan barley is a dominant cereal crop cultivated at high altitudes in Tibet. Its growth and yield are negatively affected by continuous cropping; however, the response of the rhizosphere microbial community to continuous cropping remains poorly understood. To address this question, we investigated the bacterial community structure and conducted predictive ...[more]

PMID: 33329420

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Project description:Continuous cropping often leads to an unbalanced soil microbial community, which in turn negatively affects soil functions. However, systematic research of how these effects impact the bacterial composition, microbial functional traits, and soil metabolites is lacking. In the present study, the rhizosphere soil samples of Tibetan barley continuously monocropped for 2 (CCY02), 5 (CCY05), and 10 (CCY10) years were collected. By utilizing 16S high-throughput sequencing, untargeted metabolomes, and quantitative microbial element cycling smart chips, we examined the bacterial community structure, soil metabolites, and bacterial functional gene abundances, respectively. We found that bacterial richness (based on Chao1 and Phylogenetic Diversity [PD] indices) was significantly higher in CCY02 and CCY10 than in CCY05. As per principal component analysis (PCA), samples from the continuous monocropping year tended to share more similar species compositions and soil metabolites, and exhibited distinct patterns over time. The results of the Procrustes analysis indicated that alterations in the soil metabolic profiles and bacterial functional genes after long-term continuous cropping were mainly mediated by soil microbial communities (P < 0.05). Moreover, 14 genera mainly contributed to the sample dissimilarities. Of these, five genera were identified as the dominant shared taxa, including Blastococcus, Nocardioides, Sphingomonas, Bacillus, and Solirubrobacter. The continuous cropping of Tibetan barley significantly increased the abundances of genes related to C-degradation (F = 9.25, P = 0.01) and P-cycling (F = 5.35, P = 0.03). N-cycling significantly negatively correlated with bacterial diversity (r = - 0.71, P = 0.01). The co-occurrence network analysis revealed that nine hub genera correlated with most of the functional genes and a hub taxon, Desulfuromonadales, mainly co-occurred with the metabolites via both negative and positive correlations. Collectively, our findings indicated that continuous cropping significantly altered the bacterial community structure, functioning of rhizosphere soils, and soil metabolites, thereby providing a comprehensive understanding of the effects of the long-term continuous cropping of Tibetan barley.

Project description:The continuous planting of soybeans leads to soil acidification, aggravation of soil-borne diseases, reduction in soil enzyme activity, and accumulation of toxins in the soil. Microorganisms in the rhizosphere play a very important role in maintaining the sustainability of the soil ecosystem and plant health. In this study, two soybean genotypes, one bred for continuous cropping and the other not, were grown in a Mollisol in northeast China under continuous cropping for 7 and 36years in comparison with soybean-maize rotation, and microbial communities in the rhizosphere composition were assessed using high-throughput sequencing technology. The results showed that short- or long-term continuous cropping had no significant effect on the rhizosphere soil bacterial alpha diversity. Short-term continuous planting increased the number of soybean cyst nematode (Heterodera glycines), while long-term continuous planting reduced these numbers. There were less soybean cyst nematodes in the rhizosphere of the tolerant genotypes than sensitive genotypes. In addition, continuous cropping significantly increased the potential beneficial bacterial populations, such as Pseudoxanthomonas, Nitrospira, and Streptomyces compared to rotation and short-term continuous cropping, suggesting that long-term continuous cropping of soybean shifts the microbial community toward a healthy crop rotation system. Soybean genotypes that are tolerant to soybean might recruit some microorganisms that enhance the resistance of soybeans to long-term continuous cropping. Moreover, the network of the two genotypes responded differently to continuous cropping. The tolerant genotype responded positively to continuous cropping, while for the sensitive genotype, topology analyses on the instability of microbial community in the rhizosphere suggested that short periods of continuous planting can have a detrimental effect on microbial community stability, although this effect could be alleviated with increasing periods of continuous planting.

Project description:Rhizosphere bacteria play important role in soil nutrient cycling and plant growth, and their richness and diversity are influenced by soil management systems. However, the specific changes in tobacco rhizosphere bacterial community structure in continuous and tobacco-rice rotation cropping systems remain uninvestigated. In this study, soil properties and the composition of the rhizosphere bacterial community in tobacco monocropping and tobacco-rice rotation cropping systems were analyzed. Moreover, the comparison of rhizosphere bacterial community structure between tobacco continuous and tobacco-rice rotation cropping systems was performed via high-throughput sequencing. The changes in the composition of the rhizosphere bacterial community were investigated at different tobacco growth stages. The results showed that continuous tobacco cropping increased the soil soluble organic carbon (SOC), total nitrogen (TN), and the content of other nutrients (e.g., available phosphorus and available potassium) compared to tobacco-rice rotation cropping. However, monocropping decreased bacterial alpha-diversity and altered the community composition when compared to the rotation cropping system. At the phylum level, the relative abundance of Proteobacteria, Gemmatimonadetes, and Bacteroidetes increased in the continuous cropping soil, while that of Acidobacteria, Firmicutes, and Actinobacteria decreased. At the genera level, the average abundance of the dominant genus Bacillus varied from 12.96% in continuous cropping libraries to 6.33% in the rotation cropping libraries (p < 0.05). Additionally, several other taxa, such as o_Acidobacteriales and Candidatus_Solibacter decreased from 7.63 to 6.62% (p < 0.05) and 4.52 to 2.91% (p < 0.05), respectively. However, the relative abundance of f_Gemmatimonadaceae and c_Subgroup_6 showed an increase of 1.46% (p < 0.05) and 1.63% (p < 0.05) in the tobacco-rice rotation cropping system, respectively. The results of NMDS indicated that the rhizobacteria community structure differed in the two cropping systems. In tobacco, the rhizosphere bacterial community structure showed no significant changes in the prosperous long-term stage and topping stage, but the composition changed significantly in the mature stage.

Dataset Information

Rhizosphere Bacterial Community Response to Continuous Cropping of Tibetan Barley.

Publications

Rhizosphere Bacterial Community Response to Continuous Cropping of Tibetan Barley.

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