Rhizobial communities in symbiosis with legumes: genetic diversity, competition and interactions with host plants

2012 ◽  
Vol 7 (3) ◽  
pp. 363-372 ◽  
Author(s):  
Jerzy Wielbo
Keyword(s):  
Genetic Diversity ◽  
Microbial Diversity ◽  
Species Interactions ◽  
Host Plants ◽  
Microbial Population ◽  
Environmental Adaptation ◽  
Evolutionary Perspective ◽  
Bacterial Symbiosis ◽  
As Species ◽  
Legume Symbiosis

AbstractThe term ‘Rhizobium-legume symbiosis’ refers to numerous plant-bacterial interrelationships. Typically, from an evolutionary perspective, these symbioses can be considered as species-to-species interactions, however, such plant-bacterial symbiosis may also be viewed as a low-scale environmental interplay between individual plants and the local microbial population. Rhizobium-legume interactions are therefore highly important in terms of microbial diversity and environmental adaptation thereby shaping the evolution of plant-bacterial symbiotic systems. Herein, the mechanisms underlying and modulating the diversity of rhizobial populations are presented. The roles of several factors impacting successful persistence of strains in rhizobial populations are discussed, shedding light on the complexity of rhizobial-legume interactions.

scholarly journals Genomics of sorghum local adaptation to a parasitic plant

2020 ◽  
Vol 117 (8) ◽  
pp. 4243-4251 ◽  
Author(s):  
Emily S. Bellis ◽  
Elizabeth A. Kelly ◽  
Claire M. Lorts ◽  
Huirong Gao ◽  
Victoria L. DeLeo ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Local Adaptation ◽  
Species Interactions ◽  
Balancing Selection ◽  
Control Plant ◽  
Farming Systems ◽  
Striga Hermonthica ◽  
Loss Of Function ◽  
Trade Offs ◽  
Genome Wide

Host–parasite coevolution can maintain high levels of genetic diversity in traits involved in species interactions. In many systems, host traits exploited by parasites are constrained by use in other functions, leading to complex selective pressures across space and time. Here, we study genome-wide variation in the staple crop Sorghum bicolor (L.) Moench and its association with the parasitic weed Striga hermonthica (Delile) Benth., a major constraint to food security in Africa. We hypothesize that geographic selection mosaics across gradients of parasite occurrence maintain genetic diversity in sorghum landrace resistance. Suggesting a role in local adaptation to parasite pressure, multiple independent loss-of-function alleles at sorghum LOW GERMINATION STIMULANT 1 (LGS1) are broadly distributed among African landraces and geographically associated with S. hermonthica occurrence. However, low frequency of these alleles within S. hermonthica-prone regions and their absence elsewhere implicate potential trade-offs restricting their fixation. LGS1 is thought to cause resistance by changing stereochemistry of strigolactones, hormones that control plant architecture and below-ground signaling to mycorrhizae and are required to stimulate parasite germination. Consistent with trade-offs, we find signatures of balancing selection surrounding LGS1 and other candidates from analysis of genome-wide associations with parasite distribution. Experiments with CRISPR–Cas9-edited sorghum further indicate that the benefit of LGS1-mediated resistance strongly depends on parasite genotype and abiotic environment and comes at the cost of reduced photosystem gene expression. Our study demonstrates long-term maintenance of diversity in host resistance genes across smallholder agroecosystems, providing a valuable comparison to both industrial farming systems and natural communities.

scholarly journals Species interactions enhance root allocation, microbial diversity and P acquisition in intercropped wheat and soybean under P deficiency

2017 ◽  
Vol 120 ◽  
pp. 179-188 ◽  
Author(s):  
Adnane Bargaz ◽  
Genevieve L. Noyce ◽  
Roberta Fulthorpe ◽  
Georg Carlsson ◽  
Jessie R. Furze ◽  
...  
Keyword(s):  
Microbial Diversity ◽  
Species Interactions ◽  
P Deficiency ◽  
Root Allocation ◽  
P Acquisition

scholarly journals The DNA of coral reef biodiversity: predicting and protecting genetic diversity of reef assemblages

2016 ◽  
Vol 283 (1829) ◽  
pp. 20160354 ◽  
Author(s):  
Kimberly A. Selkoe ◽  
Oscar E. Gaggiotti ◽  
Eric A. Treml ◽  
Johanna L. K. Wren ◽  
Mary K. Donovan ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Species Interactions ◽  
Allelic Richness ◽  
Coral Cover ◽  
Species Turnover ◽  
Depth Range ◽  
Ecological Communities ◽  
Effective Population ◽  
A Site ◽  
New Strategies

Conservation of ecological communities requires deepening our understanding of genetic diversity patterns and drivers at community-wide scales. Here, we use seascape genetic analysis of a diversity metric, allelic richness (AR), for 47 reef species sampled across 13 Hawaiian Islands to empirically demonstrate that large reefs high in coral cover harbour the greatest genetic diversity on average. We found that a species's life history (e.g. depth range and herbivory) mediates response of genetic diversity to seascape drivers in logical ways. Furthermore, a metric of combined multi-species AR showed strong coupling to species richness and habitat area, quality and stability that few species showed individually. We hypothesize that macro-ecological forces and species interactions, by mediating species turnover and occupancy (and thus a site's mean effective population size), influence the aggregate genetic diversity of a site, potentially allowing it to behave as an apparent emergent trait that is shaped by the dominant seascape drivers. The results highlight inherent feedbacks between ecology and genetics, raise concern that genetic resilience of entire reef communities is compromised by factors that reduce coral cover or available habitat, including thermal stress, and provide a foundation for new strategies for monitoring and preserving biodiversity of entire reef ecosystems.

scholarly journals Higher-order effects, continuous species interactions, and trait evolution shape microbial spatial dynamics

2021 ◽  
Vol 119 (1) ◽  
pp. e2020956119
Author(s):  
Anshuman Swain ◽  
Levi Fussell ◽  
William F. Fagan
Keyword(s):  
Microbial Diversity ◽  
Species Interactions ◽  
Community Dynamics ◽  
Spatial Dynamics ◽  
Higher Order ◽  
Formation Time ◽  
Community Formation ◽  
Order Effects ◽  
Disturbance Regimes ◽  
Antagonistic Interactions

The assembly and maintenance of microbial diversity in natural communities, despite the abundance of toxin-based antagonistic interactions, presents major challenges for biological understanding. A common framework for investigating such antagonistic interactions involves cyclic dominance games with pairwise interactions. The incorporation of higher-order interactions in such models permits increased levels of microbial diversity, especially in communities in which antibiotic-producing, sensitive, and resistant strains coexist. However, most such models involve a small number of discrete species, assume a notion of pure cyclic dominance, and focus on low mutation rate regimes, none of which well represent the highly interlinked, quickly evolving, and continuous nature of microbial phenotypic space. Here, we present an alternative vision of spatial dynamics for microbial communities based on antagonistic interactions—one in which a large number of species interact in continuous phenotypic space, are capable of rapid mutation, and engage in both direct and higher-order interactions mediated by production of and resistance to antibiotics. Focusing on toxin production, vulnerability, and inhibition among species, we observe highly divergent patterns of diversity and spatial community dynamics. We find that species interaction constraints (rather than mobility) best predict spatiotemporal disturbance regimes, whereas community formation time, mobility, and mutation size best explain patterns of diversity. We also report an intriguing relationship among community formation time, spatial disturbance regimes, and diversity dynamics. This relationship, which suggests that both higher-order interactions and rapid evolution are critical for the origin and maintenance of microbial diversity, has broad-ranging links to the maintenance of diversity in other systems.

scholarly journals Long-term cellulose enrichment selects for highly cellulolytic consortia and competition for public goods

2020 ◽  
Author(s):  
Gina R. Lewin ◽  
Nicole M. Davis ◽  
Bradon R. McDonald ◽  
Adam J. Book ◽  
Marc G. Chevrette ◽  
...  
Keyword(s):  
Microbial Diversity ◽  
Microbial Communities ◽  
Species Interactions ◽  
Plant Biomass ◽  
Cellulose Degradation ◽  
Soluble Sugars ◽  
Mutual Exclusion ◽  
Breakdown Product ◽  
Rrna Gene ◽  
Refuse Dumps

AbstractThe complexity of microbial communities hinders our understanding of how microbial diversity and microbe-microbe interactions impact community functions. Here, using six independent communities originating from the refuse dumps of leaf-cutter ants and enriched using the plant polymer cellulose as the sole source of carbon, we examine how changes in bacterial diversity and interactions impact plant biomass decomposition. Over up to 60 serial transfers (∼8 months), cellulolytic ability increased then stabilized in four enrichment lines and was variable in two lines. Bacterial community characterization using 16S rRNA gene amplicon sequencing showed community succession differed between the highly cellulolytic and variably cellulolytic enrichment lines. Metagenomic and metatranscriptomic analyses revealed that Cellvibrio and/or Cellulomonas dominated each enrichment line and produced the majority of cellulase enzymes, while diverse taxa were retained within these communities over the duration of transfers. Interestingly, the less cellulolytic communities had a higher diversity of organisms competing for the cellulose breakdown product cellobiose, suggesting that cheating slowed cellulose degradation. In addition, we found competitive exclusion as an important factor shaping all the communities, with the mutual exclusion of specific cellulolytic taxa within individual enrichment lines and the high expression of genes associated with the production of antagonistic compounds. Our results provide insights into how microbial diversity and competition affect the stability and function of cellulose-degrading communities.ImportanceMicrobial communities are a key driver of the carbon cycle through the breakdown of complex polysaccharides in diverse environments including soil, marine systems, and the mammalian gut.However, due to the complexity of these communities, the species-species interactions that impact community structure and ultimately shape the rate of decomposition are difficult to define. Here we performed serial enrichment on cellulose using communities inoculated from leaf-cutter ant refuse dumps, a cellulose-rich environment. By concurrently tracking cellulolytic ability and community composition and through metagenomic and metatranscriptomic sequencing, we analyzed the ecological dynamics of the enrichment lines. Our data suggest that antagonism is prevalent in these communities and that competition for soluble sugars may slow degradation and lead to community instability. Together, these results help reveal the relationships between competition and polysaccharide decomposition, with implications in diverse areas ranging from microbial community ecology to cellulosic biofuels production.

scholarly journals Evaluation of Xylella fastidiosa genetic diversity by fAFPL markers

2008 ◽  
Vol 30 (1) ◽  
pp. 202-208 ◽  
Author(s):  
Luciano Takeshi Kishi ◽  
Ester Wickert ◽  
Eliana Gertrudes de Macedo Lemos
Keyword(s):  
Genetic Diversity ◽  
Phylogenetic Relationships ◽  
Host Plants ◽  
Geographical Origin ◽  
Xylella Fastidiosa ◽  
Genetic Relationships ◽  
Single Species ◽  
Bacterial Typing ◽  
Phytopathogenic Bacterium ◽  
Different Strains

The first phytopathogenic bacterium with its DNA entirely sequenced is being detected and isolated from different host plants in several geographic regions. Although it causes diseases in cultures of economic importance, such as citrus, coffee, and grapevine little is known about the genetic relationships among different strains. Actually, all strains are grouped as a single species, Xylella fastidiosa, despite colonizing different hosts, developing symptoms, and different physiological and microbiological observed conditions. The existence of genetic diversity among X. fastidiosa strains was detected by different methodological techniques, since cultural to molecular methods. However, little is know about the phylogenetic relationships developed by Brazilian strains obtained from coffee and citrus plants. In order to evaluate it, fAFLP markers were used to verify genetic diversity and phylogenetic relationships developed by Brazilian and strange strains. fAFLP is an efficient technique, with high reproducibility that is currently used for bacterial typing and classification. The obtained results showed that Brazilian strains present genetic diversity and that the strains from this study were grouped distinctly according host and geographical origin like citrus-coffee, temecula-grapevine-mulberry and plum-elm.

Effect of Mi-1.2 gene in Natal Host Plants on Behavior and Biology of the Tomato Psyllid Bactericerca cockerelli (Sulc) (Hemiptera: Psyllidae)

2007 ◽  
Vol 42 (2) ◽  
pp. 155-162 ◽  
Author(s):  
Clare L. Casteel ◽  
Linda L. Walling ◽  
Timothy D. Paine
Keyword(s):  
Host Selection ◽  
Host Plants ◽  
Development Time ◽  
Host Preference ◽  
Solanum Lycopersicon ◽  
As Species ◽  
Useful Components ◽  
Survival And Development ◽  
Subsequent Selection ◽  
Selection Of

The Mi-1.2 gene has been isolated from wild varieties of tomato, Solanum peruvianum (Mill), and incorporated into near isogenic commercial varieties of tomato, Solanum lycopersicon. Plants containing the gene confer resistance to tomato psyllid, Bactericerca cockerelli (Sulc), as well as species of aphids, whiteflies, and nematodes. Considering bias in host preference and oviposition responses based on early adult experience is well documented in the literature; the objective of this study was to determine if the presence or absence of the Mi-1.2 in the rearing host influenced subsequent host selection, oviposition, and development time. The results presented here show that the host that psyllids developed on did not affect subsequent selection of host for oviposition, but incidence of oviposition was higher on plants that did not contain the Mi-1.2 gene [Moneymaker (mi-1.2)] compared to plants with the Mi-1.2 gene [Motelle (Mi-1.2)]. Psyllid nymph survival and development time did not differ between plant varieties. Consequently, plants containing the gene may be useful components to IPM programs to control the tomato psyllid.

scholarly journals Saturating effects of species diversity on life-history evolution in bacteria

2015 ◽  
Vol 282 (1815) ◽  
pp. 20151794 ◽  
Author(s):  
Francesca Fiegna ◽  
Thomas Scheuerl ◽  
Alejandra Moreno-Letelier ◽  
Thomas Bell ◽  
Timothy G. Barraclough
Keyword(s):  
Life History ◽  
Species Richness ◽  
Species Interactions ◽  
Evolutionary Dynamics ◽  
Life History Evolution ◽  
Relative Strength ◽  
Recent Theory ◽  
Mechanistic Models ◽  
As Species ◽  
Diverse Communities

Species interactions can play a major role in shaping evolution in new environments. In theory, species interactions can either stimulate evolution by promoting coevolution or inhibit evolution by constraining ecological opportunity. The relative strength of these effects should vary as species richness increases, and yet there has been little evidence for evolution of component species in communities. We evolved bacterial microcosms containing between 1 and 12 species in three different environments. Growth rates and yields of isolates that evolved in communities were lower than those that evolved in monocultures, consistent with recent theory that competition constrains species to specialize on narrower sets of resources. This effect saturated or reversed at higher levels of richness, consistent with theory that directional effects of species interactions should weaken in more diverse communities. Species varied considerably, however, in their responses to both environment and richness levels. Mechanistic models and experiments are now needed to understand and predict joint evolutionary dynamics of species in diverse communities.

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