Microbial rhodopsins on leaf surfaces of terrestrial plants

Faculty of Biology, Lorry I Lokey Interdisciplinary Center for Life Sciences and Engineering, Faculty of Computer Science, Technion - Israel Institute of Technology, Haifa 32000, Israel.
Environmental Microbiology (Impact Factor: 6.2). 09/2011; 14(1):140-6. DOI: 10.1111/j.1462-2920.2011.02554.x
Source: PubMed


The above-ground surfaces of terrestrial plants, the phyllosphere, comprise the main interface between the terrestrial biosphere and solar radiation. It is estimated to host up to 10(26) microbial cells that may intercept part of the photon flux impinging on the leaves. Based on 454-pyrosequencing-generated metagenome data, we report on the existence of diverse microbial rhodopsins in five distinct phyllospheres from tamarisk (Tamarix nilotica), soybean (Glycine max), Arabidopsis (Arabidopsis thaliana), clover (Trifolium repens) and rice (Oryza sativa). Our findings, for the first time describing microbial rhodopsins from non-aquatic habitats, point towards the potential coexistence of microbial rhodopsin-based phototrophy and plant chlorophyll-based photosynthesis, with the different pigments absorbing non-overlapping fractions of the light spectrum.

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    • "One of the possible advantages of foliar application is that it avoids the adverse influences of many biotic and abiotic factors on soil environment (Pandey et al. 2013). Another is the wide surface area of global terrestrial plants (an estimated 6.4×10 8 km 2 ) (Atamna-Ismaeel et al. 2012; Penuelas and Terradas 2014), with an immensely diverse microbes (of up to 10 6 –10 7 cells per cm 2 leaf surface) for plant growth promotion (Lindow and Brandl 2003). In view of these aspects, the inoculation of R. palustris onto plant leaf surface would potentially improve plant growth in a more straightforward way, and such effects would inevitably reflect on soil microbial properties due to the important roles of microbes on the plant-soil ecosystem. "
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    ABSTRACT: Purpose The extract of Stevia residue is an ideal substitute for cultivation of the purple nonsulfur bacterium, like Rhodopseudomonas palustris (R. palustris). But the influence of R. palustris grown under residue extract on its downstream application is still not well-characterized. The objective of this study was to assess the effect of foliar spray of R. palustris grown under Stevia residue extract on the plant growth and soil microbial properties. Materials and methods A pot experiment was carried out under the greenhouse condition, consisting of four treatments varying in the sprayed substances: sterilized water (control), R. palustris grown under the chemical medium supplemented with L-tryptophan (SyT), R. palustris grown under Stevia residue extract supplemented with L-tryptophan (ExT), and R. palustris grown under Stevia residue extract supplemented with NH4Cl (ExT). The net photosynthesis rate of the uppermost leaves was measured with a portable photosynthesis system. Soil microbial activity was analyzed by microcalorimetry. Soil bacterial community components were determined by real-time quantitative PCR (qPCR) and high-throughput sequencing techniques. Results and discussion Compared with SyT, the R. palustris grown under Stevia residue extract not only improved the plant biomass and the net photosynthetic rate to a large extent, but also increased soil microbial metabolic activity and altered community compositions as well. The treatments receiving R. palustris, especially ExT and ExN, increased the relative abundances of some functional guilds involved in C turnover and nutrient cycling in soil, including Acidobacteria, Actinobacteria, Proteobacteria, Gemmatimonadaetes, Nitrospirae, and Planctomycetes. Conclusions R. palustris grown under the Stevia residue extract showed advantages over that under the chemical medium on both plant growth and soil microbial properties. One of the possible reasons could result from the increases in microbial activity and several bacterial keystone guilds involved into C and nutrient cycling, both of which potentially contribute to the improved plant growth. The results would be conducive to the downstream application of R. palustris in an economical way.
    Journal of Soils and Sediments 09/2015; DOI:10.1007/s11368-015-1269-1 · 2.14 Impact Factor
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    • "Microbial epiphytes, able to thrive on the leaf surface, have evolved different adaptations to cope with these extreme conditions. A phototrophic lifestyle on the leaf surface has been suggested based on the identification of microbial rhodopsins (Atamna-Ismaeel et al., 2011; Vorholt, 2012). Some of these proteins could act as proton pumps, providing additional energy to diverse members of the phylosphere. "
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    New Phytologist 01/2015; 206(4). DOI:10.1111/nph.13312 · 7.67 Impact Factor
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    • "The first metagenomes, -proteomes, and -transcriptomes are currently published (Delmotte et al., 2009; Knief et al., 2012). An interesting example for a novel function is the detection of potential coexistence of microbial and plant photosynthesis on Tamarix leaves (Atamna-Ismaeel et al., 2012). Functional analysis will demonstrate whether the plants are able to benefit from the presence of certain microorganisms. "
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    ABSTRACT: Most eukaryotes develop close interactions with microorganisms that are essential for their performance and survival. Thus, eukaryotes and prokaryotes in nature can be considered as meta-organisms or holobionts. Consequently, microorganisms that colonize different plant compartments contain the plant's second genome. In this respect, many studies in the last decades have shown that plant-microbe interactions are not only crucial for better understanding plant growth and health, but also for sustainable crop production in a changing world. This mini-review acting as editorial presents retrospectives and future perspectives for plant microbiome studies as well as information gaps in this emerging research field. In addition, the contribution of this research topic to the solution of various issues is discussed.
    Frontiers in Microbiology 06/2014; 5:148. DOI:10.3389/fmicb.2014.00148 · 3.99 Impact Factor
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