Bacteriocin-producing native rhizobia of green gram (Vigna radiata) having competitive advantage in nodule occupancy

Goel, A. K.; Sindhu, S. S.; Dadarwal, K. R.

doi:10.1016/s0944-5013(99)80033-0

Cited by 20 publications

(14 citation statements)

References 22 publications

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“…Joining a biofilm 'selfish herd' [56,57] might provide protection from predation. A persister's antibiotic resistance might be particularly useful in biofilms, surrounded by so many potentially hostile neighbors, although persister resistance to the bacteriocins rhizobia use against each other [58,59] has not yet been determined. In summary, it is wellestablished that rhizobial populations can survive in soil for years without hosts, and individual cells can survive for over a year as persisters.…”

Section: Survival In the Soilmentioning

confidence: 99%

Life Histories of Symbiotic Rhizobia and Mycorrhizal Fungi

2011

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Research on life history strategies of microbial symbionts is key to understanding the evolution of cooperation with hosts, but also their survival between hosts. Rhizobia are soil bacteria known for fixing nitrogen inside legume root nodules. Arbuscular mycorrhizal (AM) fungi are ubiquitous root symbionts that provide plants with nutrients and other benefits. Both kinds of symbionts employ strategies to reproduce during symbiosis using host resources; to repopulate the soil; to survive in the soil between hosts; and to find and infect new hosts. Here we focus on the fitness of the microbial symbionts and how interactions at each of these stages has shaped microbial life-history strategies. During symbiosis, microbial fitness could be increased by diverting more resources to individual reproduction, but that may trigger fitness-reducing host sanctions. To survive in the soil, symbionts employ sophisticated strategies, such as persister formation for rhizobia and reversal of spore germination by mycorrhizae. Interactions among symbionts, from rhizobial quorum sensing to fusion of genetically distinct fungal hyphae, increase adaptive plasticity. The evolutionary implications of these interactions and of microbial strategies to repopulate and survive in the soil are largely unexplored.

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Section: Survival In the Soilmentioning

confidence: 99%

Life Histories of Symbiotic Rhizobia and Mycorrhizal Fungi

2011

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“…It has been suggested that strains characterized by increased aggression towards conspecifics in high fertility soils are unlikely to be good mutualists (Johnson 1993; Graham, Drouillard & Hodge 1996; Johnson, Graham & Smith 1997). Investment in antibiotic production, for example, can come at the expense of symbiotic performance, as seen with rhizobia (Goel, Sindhu & Dadarwal 1999).…”

Section: Variation In Resources and Productivity: Effects Of Increasementioning

confidence: 99%

Mediating mutualisms: farm management practices and evolutionary changes in symbiont co‐operation

Kiers

West

Denison

2002

Journal of Applied Ecology

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Summary1. Root symbionts (rhizobia and arbuscular mycorrhizae) are often assumed to increase agricultural productivity consistently. However, rhizobial and mycorrhizal strains vary in effectiveness, resulting in symbiotic associations that range from parasitic to mutualistic. 2. The extent to which different farming practices mediate evolutionary changes along this continuum of symbiont effectiveness is rarely discussed. However, evolutionary theory suggests that (i) fertilizer use will favour parasitism unless host-plants impose sanctions against less-effective mutualists; (ii) tillage will have contrasting effects because it decreases within-plant symbiont relatedness but also decreases the risk that mutualism will benefit future competitors; (iii) crop rotation can act as a selective agent against dominating symbiont genotypes; and (iv) rhizobial inoculation adds beneficial strains to the soil but may increase the frequency of mixed nodules that allow parasitic strains to escape host sanctions. 3. However, the existing empirical data are inadequate to test our predictions thoroughly. Changes in species composition have been documented as a result of management practices, but evolutionary changes in symbiont effectiveness are difficult to detect. Therefore, a major aim of this study was to stimulate research that will assesses directly changes in symbiotic effectiveness as a function of management practices.

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“…This appears to suggest that bacteriocins may play a defensive role in limiting competition among bacteria, essentially giving the producing cells a competitive advantage over the nonproducing sensitive strains. The ability of bacteriocin-producing strains to reduce sensitive strains when grown together has been shown previously (13,18,33,42,49,53).…”

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confidence: 69%

Relative Importance of Bacteriocin-Like Genes in Antagonism ofXanthomonas perforansTomato Race 3 toXanthomonas euvesicatoriaTomato Race 1 Strains

Hert

Roberts

Momol

et al. 2005

Appl Environ Microbiol

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In a previous study, tomato race 3 (T3) strains of Xanthomonas perforans became predominant in fields containing both X. euvesicatoria and X. perforans races T1 and T3, respectively. This apparent ability to take over fields led to the discovery that there are three bacteriocin-like compounds associated with T3 strains. Bacterial spot of tomatoes and peppers is caused by Xanthomonas campestris pv. vesicatoria. Pohronezny and Volin (34) estimated that as high as 50% loss of marketable fruit was due to bacterial spot on tomatoes. Control of bacterial spot of tomato is difficult when high temperatures and high moisture exist. Bactericides, such as fixed coppers and streptomycin, have provided the primary means of control (30,45,46); however, streptomycin-resistant mutants and copper-tolerant strains became prevalent on treated plants (46). Marco and Stall (30) showed that many Xanthomonas euvesicatoria strains were tolerant of copper and addition of mancozeb to copper sprays improved control of the copper-tolerant strains (6, 30). However, they also showed that this treatment is insufficient when conditions favorable for disease development exist.On tomato, three races, designated tomato race 1 (T1), T2, and T3, were identified based on their reaction on three tomato genotypes (25,26, 44). Recent reclassification of the xanthomonads associated with bacterial spot of tomato has changed the species classification of these races. Currently, T1 strains are classified as X. euvesicatoria, T2 strains are classified as X. vesicatoria, and T3 strains are now classified as Xanthomonas perforans (24). T1 and T2 were first identified in 1990 (55) and are distributed worldwide (3), although only T1 strains were present in Florida until the early 1990s. In 1991, T3 appeared in Florida fields (26) and eventually predominated (22). This new race had antagonistic activity toward T1 strains (8) and was determined to be a new group designated group C (23). Genetically, T3 strains are most closely related to T1 strains based on DNA similarity values (23).In a previous study, wild type (WT) T3 strains were shown to be antagonistic toward WT T1 strains (8). Tudor-Nelson et al. (52) identified three cosmid clones, designated BCN-A, BCN-B, and BCN-C, which were found to confer the ability to inhibit a sensitive T1 strain in plate assays. These compounds were determined to have narrow inhibition spectra and fit the definition of a bacteriocin described by Reeves (36) based on the following criteria: (i) the presence of a biologically active protein moiety, (ii) inducibility with mitomycin C, and (iii) non-self inhibition (52). The three clones isolated by TudorNelson et al. (52) were unique in activity and specificity based on differential inhibition of selected sensitive T1 and T2 strains (52). It has been speculated that the bacteriocins may confer in part or completely this competitive advantage.Of the bacteriocins which have been well characterized in

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Bacteriocin-producing native rhizobia of green gram (Vigna radiata) having competitive advantage in nodule occupancy

Cited by 20 publications

References 22 publications

Life Histories of Symbiotic Rhizobia and Mycorrhizal Fungi

Life Histories of Symbiotic Rhizobia and Mycorrhizal Fungi

Mediating mutualisms: farm management practices and evolutionary changes in symbiont co‐operation

Relative Importance of Bacteriocin-Like Genes in Antagonism ofXanthomonas perforansTomato Race 3 toXanthomonas euvesicatoriaTomato Race 1 Strains

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