Infection of Intact Roots of Kallar Grass and Rice Seedlings by Azoarcus

Hurek, Thomas; Reinhold-Hurek, B.; Montagu, Marc Van; Kellenberger, E.

doi:10.1007/978-94-011-3486-6_41

Cited by 30 publications

(11 citation statements)

References 5 publications

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“…A variety of endophytic nitrogen-fixing bacteria have already been found that colonize the interior roots of rice, maize, and grass (Cocking et al, 1990;Diem et al, 1978;Hurek et al, 1991;Patriquin and Döbereiner, 1978;Barraquio et al, 1997), and are believed capable of contributing directly to the nitrogen requirement in sugarcane (Boddey et al, 1995), rice Yanni et al, 1997), and wheat . 15 N nitrogen balance studies conclude that certain Brazilian cultivars of sugarcane obtain over half their needs for nitrogen from BNF (>150 kg N ha -1 year -1 ) (see Boddey et al, 1995 for review).…”

Section: Nitrogen-fixing Bacteria In Nonlegumesmentioning

confidence: 97%

Bacterial Endophytes: Potential Role in Developing Sustainable Systems of Crop Production

Sturz

Christie

Nowak

2000

Critical Reviews in Plant Sciences

492

253

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Section: Nitrogen-fixing Bacteria In Nonlegumesmentioning

confidence: 97%

Bacterial Endophytes: Potential Role in Developing Sustainable Systems of Crop Production

Sturz

Christie

Nowak

2000

Critical Reviews in Plant Sciences

492

253

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“…Among the first solid light and electron microscopic demonstrations of endophytic colonization that extended to the stele of nondiseased plants was a report on the diazotroph Azoarcus sp. BH72 in grasses (49), in which the bacterial capacity to invade without helper organisms was shown in a gnotobiotic plant-microbe system by immunological techniques. Tagging of strains with fluorescent reporter proteins (Figure 1) provides a proof of an endophytic lifestyle (83).…”

Section: Endophytesmentioning

confidence: 99%

Roots Shaping Their Microbiome: Global Hotspots for Microbial Activity

Reinhold‐Hurek

Bünger

Burbano

et al. 2015

Annu. Rev. Phytopathol.

616

379

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Land plants interact with microbes primarily at roots. Despite the importance of root microbial communities for health and nutrient uptake, the current understanding of the complex plant-microbe interactions in the rhizosphere is still in its infancy. Roots provide different microhabitats at the soil-root interface: rhizosphere soil, rhizoplane, and endorhizosphere. We discuss technical aspects of their differentiation that are relevant for the functional analysis of their different microbiomes, and we assess PCR (polymerase chain reaction)-based methods to analyze plant-associated bacterial communities. Development of novel primers will allow a less biased and more quantitative view of these global hotspots of microbial activity. Based on comparison of microbiome data for the different root-soil compartments and on knowledge of bacterial functions, a three-step enrichment model for shifts in community structure from bulk soil toward roots is presented. To unravel how plants shape their microbiome, a major research field is likely to be the coupling of reductionist and molecular ecological approaches, particularly for specific plant genotypes and mutants, to clarify causal relationships in complex root communities.

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“…(A preliminary account of this study was presented previously [22].) MATERIALS AND METHODS Bacterial strains and plants.…”

mentioning

confidence: 99%

Root colonization and systemic spreading of Azoarcus sp. strain BH72 in grasses

et al. 1994

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The invasive properties of Azoarcus sp. strain BH72, an endorhizospheric isolate of Kallar grass, on gnotobiotically grown seedlings of Oryza sativa IR36 and Leptochloafusca (L.) Kunth were studied. Additionally, Azoarcus spp. were localized in roots of field-grown Kallar grass. To facilitate localization and to assure identity of bacteria, genetically engineered microorganisms expressing 0-glucuronidase were also used as inocula.P-Glucuronidase staining indicated that the apical region of the root behind the meristem was the most intensively colonized. Light and electron microscopy showed that strain BH72 penetrated the rhizoplane preferentially in the zones of elongation and differentiation and colonized the root interior inter-and intracellularly. In addition to the root cortex, stelar tissue was also colonized; bacteria were found in the xylem. No evidence was obtained that Azoarcus spp. could reside in living plant cells; rather, plant cells were apparently destroyed after bacteria had penetrated the cell wall. A common pathogenicity test on tobacco leaves provided no evidence that representative strains of Azoarcus spp. are phytopathogenic. Compared with the control, inoculation with strain BH72 significantly promoted growth of rice seedlings. This effect was reversed when the plant medium was supplemented with malate (0.2 g/liter). N2 fixation was apparently not involved, because the same response was obtained with a nifK mutant of strain BH72, which has a Nif-phenotype. Also, Western blot (immunoblot) analysis of protein extracts from rice seedlings gave no indication that nitrogenase was present. PCR and Western immunoblotting, using primers specific for eubacteria and antibodies recognizing type-specific antigens, respectively, indicated that strain BH72 could colonize rice plants systemically, probably mediated by longitudinal spreading through vessels.

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Infection of Intact Roots of Kallar Grass and Rice Seedlings by Azoarcus

Cited by 30 publications

References 5 publications

Bacterial Endophytes: Potential Role in Developing Sustainable Systems of Crop Production

Bacterial Endophytes: Potential Role in Developing Sustainable Systems of Crop Production

Roots Shaping Their Microbiome: Global Hotspots for Microbial Activity

Root colonization and systemic spreading of Azoarcus sp. strain BH72 in grasses

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