Soil microbial community structure in cucumber rhizosphere of different resistance cultivars to fusarium wilt.
ABSTRACT Cucumber fusarium wilt is a common soil-borne disease. We hypothesize that there is a relationship between the severity of disease and soil microbial ecology. In this work, culturable microbial populations, lipid fatty acid and community-level physiological profiles (CLPP) from rhizosphere soils of four different cucumber cultivars were investigated. Comparatively higher actinomycetes, mycorrhizal colonization and higher ratios of bacteria to fungi were found in the two resistant cultivars compared with the two susceptible cultivars. CLPP analysis showed that catabolic diversity indices were higher in the presence of two resistant cultivars. Phospholipid fatty acid (PLFA) profiles suggested that fungal (18:2omega6,9c) PLFA was enriched in the rhizosphere soils of the two susceptible cultivars, but some bacterial (16:0 and 15:0a) PLFAs were found in a lower relative abundance in these soils. The neutral lipid fatty acid 16:1omega5, which is an indicator of arbuscular mycorrhizal fungi, was enriched in the rhizosphere soils of the two resistant cultivars. All the three methods suggested that plant genotype had a significant impact on the soil microbial community composition and activity, and the differences in the rhizosphere microbial community may result in the differences in the resistance to fusarium wilt.
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ABSTRACT: The rhizosphere is the interface between plant roots and soil where interactions among a myriad of microorganisms and invertebrates affect biogeochemical cycling, plant growth and tolerance to biotic and abiotic stress. The rhizosphere is intriguingly complex and dynamic, and understanding its ecology and evolution is key to enhancing plant productivity and ecosystem functioning. Novel insights into key factors and evolutionary processes shaping the rhizosphere microbiome will greatly benefit from integrating reductionist and systems-based approaches in both agricultural and natural ecosystems. Here, we discuss recent developments in rhizosphere research in relation to assessing the contribution of the micro- and macroflora to sustainable agriculture, nature conservation, the development of bio-energy crops and the mitigation of climate change.Nature Reviews Microbiology 09/2013; · 22.49 Impact Factor
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ABSTRACT: Microbes are vital to the earth because of their enormous numbers and instinct function maintaining the natural balance. Since the microbiology was applied in environmental science and engineering more than a century ago, researchers desire for more and more information concerning the microbial spatio-temporal variations in almost every fields from contaminated soil to wastewater treatment plant (WWTP). For the past 30 years, molecular biologic techniques explored for environmental microbial community (EMC) have spanned a broad range of approaches to facilitate the researches with the assistance of computer science: faster, more accurate and more sensitive. In this feature article, we outlined several current and emerging molecular biologic techniques applied in detection of EMC, and presented and assessed in detail the application of three promising tools.Frontiers of Environmental Science & Engineering in China 08/2013; · 0.75 Impact Factor
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ABSTRACT: Phytoremediation for PAH hydrocarbons has been widely studied, but few focus on the influence of rhizodeposition on their bioaccessibility during the process. This literature revealed the effect of celery (Apium graveolens) rhizodeposition on pyrene fractionation and bioaccessibility in simulated pyrene and pyrene-lead contaminated microcosms. A sequential extraction methodology was used to quantify different morphological fractions of pyrene in the soil, and phospholipid fatty acid (PLFA) pattern to monitor shifts in microbial populations. Bioaccessible pyrene accounted for the largest proportion of the total removal. Biodegradation of both bioaccessible and associated pyrene fractions was enhanced by celery rhizodeposition in pyrene spiked soils. However, rhizodeposition promoted the removal of bioaccessible rather than associated fractions in pyrene-lead spiked soils. In contrast, the bound fraction increased over time in pyrene spiked soils without amendment, but kept relatively stable in amended microcosms. It was found that rhizodeposition facilitated the reproduction of all the subgroups of soil microorganisms through PLFA analysis. Although all the subgroups contributed to the removal of bioaccessible pyrene, only abundances of unsaturated and cyclic fatty acids were positively correlated with the removal of associated pyrene. These findings provide meaningful insights into the microecological mechanisms involved in the phytoremediation of PAH polluted sites.Chemosphere 11/2013; · 3.14 Impact Factor