scholarly journals Inbreeding and disease resistance in a social insect: effects of heterozygosity on immunocompetence in the termite Zootermopsis angusticollis

2006 ◽  
Vol 273 (1601) ◽  
pp. 2633-2640 ◽  
Author(s):  
Daniel V Calleri ◽  
Ellen McGrail Reid ◽  
Rebeca B Rosengaus ◽  
Edward L Vargo ◽  
James F.A Traniello
Keyword(s):  
Genetic Variation ◽  
Disease Resistance ◽  
Allelic Diversity ◽  
Bacterial Pathogen ◽  
Group Living ◽  
Pathogen Transmission ◽  
High Concentration ◽  
Susceptibility To Infection ◽  
Zootermopsis Angusticollis ◽  
Increase Disease Susceptibility

Recent research has shown that low genetic variation in individuals can increase susceptibility to infection and group living may exacerbate pathogen transmission. In the eusocial diploid termites, cycles of outbreeding and inbreeding characterizing basal species can reduce genetic variation within nestmates during the life of a colony, but the relationship of genetic heterogeneity to disease resistance is poorly understood. Here we show that, one generation of inbreeding differentially affects the survivorship of isolated and grouped termites ( Zootermopsis angusticollis) depending on the nature of immune challenge and treatment. Inbred and outbred isolated and grouped termites inoculated with a bacterial pathogen, exposed to a low dose of fungal pathogen or challenged with an implanted nylon monofilament had similar levels of immune defence. However, inbred grouped termites exposed to a relatively high concentration of fungal conidia had significantly greater mortality than outbred grouped termites. Inbred termites also had significantly higher cuticular microbial loads, presumably due to less effective grooming by nestmates. Genetic analyses showed that inbreeding significantly reduced heterozygosity and allelic diversity. Decreased heterozygosity thus appeared to increase disease susceptibility by affecting social behaviour or some other group-level process influencing infection control rather than affecting individual immune physiology.

scholarly journals A 2′-O-Methyltransferase Responsible for Transfer RNA Anticodon Modification Is Pivotal for Resistance to Pseudomonas syringae DC3000 in Arabidopsis

2018 ◽  
Vol 31 (12) ◽  
pp. 1323-1336 ◽  
Author(s):  
Vicente Ramírez ◽  
Beatriz González ◽  
Ana López ◽  
Maria Jose Castelló ◽  
Maria José Gil ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Pseudomonas Syringae ◽  
Bacterial Pathogen ◽  
Transfer Rna ◽  
Resistance Response ◽  
Chemical Structures ◽  
Trna Modifications ◽  
Trna Species ◽  
Living Organisms ◽  
And Function

Transfer RNA (tRNA) is the most highly modified class of RNA species in all living organisms. Recent discoveries have revealed unprecedented complexity in the tRNA chemical structures, modification patterns, regulation, and function, suggesting that each modified nucleoside in tRNA may have its own specific function. However, in plants, our knowledge of the role of individual tRNA modifications and how they are regulated is very limited. In a genetic screen designed to identify factors regulating disease resistance in Arabidopsis, we identified SUPPRESSOR OF CSB3 9 (SCS9). Our results reveal SCS9 encodes a tRNA methyltransferase that mediates the 2′-O-ribose methylation of selected tRNA species in the anticodon loop. These SCS9-mediated tRNA modifications enhance susceptibility during infection with the virulent bacterial pathogen Pseudomonas syringae DC3000. Lack of such tRNA modification, as observed in scs9 mutants, specifically dampens plant resistance against DC3000 without compromising the activation of the salicylic acid signaling pathway or the resistance to other biotrophic pathogens. Our results support a model that gives importance to the control of certain tRNA modifications for mounting an effective disease resistance in Arabidopsis toward DC3000 and, therefore, expands the repertoire of molecular components essential for an efficient disease resistance response.

scholarly journals Feeder density enhances house finch disease transmission in experimental epidemics

2018 ◽  
Vol 373 (1745) ◽  
pp. 20170090 ◽  
Author(s):  
Sahnzi C. Moyers ◽  
James S. Adelman ◽  
Damien R. Farine ◽  
Courtney A. Thomason ◽  
Dana M. Hawley
Keyword(s):  
Radio Frequency Identification ◽  
Disease Transmission ◽  
Bacterial Pathogen ◽  
Pathogen Transmission ◽  
House Finch ◽  
Resource Subsidies ◽  
House Finches ◽  
Bird Feeders ◽  
Group Members ◽  
Radio Frequency Identification Devices

Anthropogenic food provisioning of wildlife can alter the frequency of contacts among hosts and between hosts and environmental sources of pathogens. Despite the popularity of garden bird feeding, few studies have addressed how feeders influence host contact rates and disease dynamics. We experimentally manipulated feeder density in replicate aviaries containing captive, pathogen-naive, groups of house finches ( Haemorhous mexicanus ) and continuously tracked behaviours at feeders using radio-frequency identification devices. We then inoculated one bird per group with Mycoplasma gallisepticum (Mg), a common bacterial pathogen for which feeders are fomites of transmission, and assessed effects of feeder density on house finch behaviour and pathogen transmission. We found that pathogen transmission was significantly higher in groups with the highest density of bird feeders, despite a significantly lower rate of intraspecific aggressive interactions relative to the low feeder density groups. Conversely, among naive group members that never showed signs of disease, we saw significantly higher concentrations of Mg-specific antibodies in low feeder density groups, suggesting that birds in low feeder density treatments had exposure to subclinical doses of Mg. We discuss ways in which the density of garden bird feeders could play an important role in mediating the intensity of Mg epidemics. This article is part of the theme issue ‘Anthropogenic resource subsidies and host–parasite dynamics in wildlife'.

scholarly journals Contrasting genetic variation and positive selection followed the divergence of NBS-encoding genes in Asian and European pears

BMC Genomics ◽  
2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Manyi Sun ◽  
Mingyue Zhang ◽  
Jugpreet Singh ◽  
Bobo Song ◽  
Zikai Tang ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Disease Resistance ◽  
Positive Selection ◽  
Gene Family ◽  
Selection Pressure ◽  
Black Spot ◽  
Orthologous Gene ◽  
European Pear ◽  
Encoding Gene ◽  
Encoding Genes

Abstract Background The NBS disease-related gene family coordinates the inherent immune system in plants in response to pathogen infections. Previous studies have identified NBS-encoding genes in Pyrus bretschneideri (‘Dangshansuli’, an Asian pear) and Pyrus communis (‘Bartlett’, a European pear) genomes, but the patterns of genetic variation and selection pressure on these genes during pear domestication have remained unsolved. Results In this study, 338 and 412 NBS-encoding genes were identified from Asian and European pear genomes. This difference between the two pear species was the result of proximal duplications. About 15.79% orthologous gene pairs had Ka/Ks ratio more than one, indicating two pear species undergo strong positive selection after the divergence of Asian and European pear. We identified 21 and 15 NBS-encoding genes under fire blight and black spot disease-related QTL, respectively, suggesting their importance in disease resistance. Domestication caused decreased nucleotide diversity across NBS genes in Asian cultivars (cultivated 6.23E-03; wild 6.47E-03), but opposite trend (cultivated 6.48E-03; wild 5.91E-03) appeared in European pears. Many NBS-encoding coding regions showed Ka/Ks ratio of greater than 1, indicating the role of positive selection in shaping diversity of NBS-encoding genes in pear. Furthermore, we detected 295 and 122 significantly different SNPs between wild and domesticated accessions in Asian and European pear populations. Two NBS genes (Pbr025269.1 and Pbr019876.1) with significantly different SNPs showed >5x upregulation between wild and cultivated pear accessions, and > 2x upregulation in Pyrus calleryana after inoculation with Alternaria alternata. We propose that positively selected and significantly different SNPs of an NBS-encoding gene (Pbr025269.1) regulate gene expression differences in the wild and cultivated groups, which may affect resistance in pear against A. alternata. Conclusion Proximal duplication mainly led to the different number of NBS-encoding genes in P. bretschneideri and P. communis genomes. The patterns of genetic diversity and positive selection pressure differed between Asian and European pear populations, most likely due to their independent domestication events. This analysis helps us understand the evolution, diversity, and selection pressure in the NBS-encoding gene family in Asian and European populations, and provides opportunities to study mechanisms of disease resistance in pear.

scholarly journals Sexual antagonism for resistance and tolerance to infection in Drosophila melanogaster

2014 ◽  
Vol 281 (1788) ◽  
pp. 20140987 ◽  
Author(s):  
Crystal M. Vincent ◽  
Nathaniel P. Sharp
Keyword(s):  
Drosophila Melanogaster ◽  
Genetic Variation ◽  
Sexual Dimorphism ◽  
Bacterial Pathogen ◽  
Ecological Factors ◽  
Evolutionary Genetics ◽  
Antagonistic Pleiotropy ◽  
Sexual Antagonism ◽  
Heritable Variation ◽  
Dioecious Populations

A critical task in evolutionary genetics is to explain the persistence of heritable variation in fitness-related traits such as immunity. Ecological factors can maintain genetic variation in immunity, but less is known about the role of other factors, such as antagonistic pleiotropy, on immunity. Sexually dimorphic immunity—with females often being more immune-competent—may maintain variation in immunity in dioecious populations. Most eco-immunological studies assess host resistance to parasites rather than the host's ability to maintain fitness during infection (tolerance). Distinguishing between resistance and tolerance is important as they are thought to have markedly different evolutionary and epidemiological outcomes. Few studies have investigated tolerance in animals, and the extent of sexual dimorphism in tolerance is unknown. Using males and females from 50 Drosophila melanogaster genotypes, we investigated possible sources of genetic variation for immunity by assessing both resistance and tolerance to the common bacterial pathogen Pseudomonas aeruginosa. We found evidence of sexual dimorphism and sexual antagonism for resistance and tolerance, and a trade-off between the two traits. Our findings suggest that antagonistic pleiotropy may be a major contributor to variation in immunity, with implications for host–parasite coevolution.

scholarly journals Protein interaction networks at the host–microbe interface in Diaphorina citri , the insect vector of the citrus greening pathogen

2017 ◽  
Vol 4 (2) ◽  
pp. 160545 ◽  
Author(s):  
J. S. Ramsey ◽  
J. D. Chavez ◽  
R. Johnson ◽  
S. Hosseinzadeh ◽  
J. E. Mahoney ◽  
...  
Keyword(s):  
Protein Interaction ◽  
Bacterial Pathogen ◽  
Pathogen Transmission ◽  
Protein Interaction Networks ◽  
Interaction Networks ◽  
Differentially Expressed ◽  
Citrus Greening ◽  
Insect Vector ◽  
Diaphorina Citri ◽  
Citrus Greening Disease

The Asian citrus psyllid ( Diaphorina citri) is the insect vector responsible for the worldwide spread of ‘ Candidatus Liberibacter asiaticus’ (CLas), the bacterial pathogen associated with citrus greening disease. Developmental changes in the insect vector impact pathogen transmission, such that D. citri transmission of CLas is more efficient when bacteria are acquired by nymphs when compared with adults. We hypothesize that expression changes in the D. citri immune system and commensal microbiota occur during development and regulate vector competency. In support of this hypothesis, more proteins, with greater fold changes, were differentially expressed in response to CLas in adults when compared with nymphs, including insect proteins involved in bacterial adhesion and immunity. Compared with nymphs, adult insects had a higher titre of CLas and the bacterial endosymbionts Wolbachia, Profftella and Carsonella. All Wolbachia and Profftella proteins differentially expressed between nymphs and adults are upregulated in adults, while most differentially expressed Carsonella proteins are upregulated in nymphs. Discovery of protein interaction networks has broad applicability to the study of host–microbe relationships. Using protein interaction reporter technology, a D. citri haemocyanin protein highly upregulated in response to CLas was found to physically interact with the CLas coenzyme A (CoA) biosynthesis enzyme phosphopantothenoylcysteine synthetase/decarboxylase. CLas pantothenate kinase, which catalyses the rate-limiting step of CoA biosynthesis, was found to interact with a D. citri myosin protein. Two Carsonella enzymes involved in histidine and tryptophan biosynthesis were found to physically interact with D. citri proteins. These co-evolved protein interaction networks at the host–microbe interface are highly specific targets for controlling the insect vector responsible for the spread of citrus greening.

Investigation of the genetic diversity of an invasive whitefly (Bemisia tabaci) in China using both mitochondrial and nuclear DNA markers

2011 ◽  
Vol 101 (4) ◽  
pp. 467-475 ◽  
Author(s):  
D. Chu ◽  
C.S. Gao ◽  
P. De Barro ◽  
F.H. Wan ◽  
Y.J. Zhang
Keyword(s):  
Genetic Variation ◽  
Bemisia Tabaci ◽  
Nuclear Dna ◽  
Ornamental Plants ◽  
Geographic Origin ◽  
Haplotype Diversity ◽  
Allelic Diversity ◽  
Western Mediterranean ◽  
Apparent Paradox ◽  
Key Factor

AbstractIt is often considered that reduced genetic variation due to bottlenecks and founder effects limits the capacity for species to establish in new environments and subsequently spread. The recent invasion (during the past five years) of an alien whitefly, one member of Bemisia tabaci cryptic species complex, referred to as Mediterranean (herein referred to as Q-type) in Shandong Province, China, provides an ideal opportunity to study the changes in genetic variation between its home range in the Mediterranean region and its invasion range. Using both the mitochondrial cytochrome oxidase I (mtCOI) and nuclear (microsatellite) DNA, we show that Q in Shandong likely originated in the western Mediterranean. We also found that the haplotype diversity was low compared with its presumed geographic origin, whereas microsatellite allele diversity showed no such decline. A key factor in invasions is the establishment of females and so bottleneck and founder events can lead to a very rapid and considerable loss of mitochondrial diversity. The lack of haplotype diversity in Shandong supports the interpretation that, at one or more points between the western Mediterranean and China, the invading Q lost haplotype diversity, most probably through the serial process of establishment and redistribution through trade in ornamental plants. However, the loss in haplotype diversity does not necessarily mean that nuclear allelic diversity should also decline. Provided females can mate freely with whichever males are available, allelic diversity can be maintained or even increased relative to the origin of the invader. Our findings may offer some explanation to the apparent paradox between the concept of reduced genetic variation limiting adaptation to new environments and the observed low diversity in successful invaders.

Population genetic structure of the Gulf of St. Lawrence aster, Symphyotrichum laurentianum (Asteraceae), a threatened coastal endemic

Botany ◽  
2009 ◽  
Vol 87 (11) ◽  
pp. 1089-1095 ◽  
Author(s):  
Stephen B. Heard ◽  
Linley K. Jesson ◽  
Kirby Tulk
Keyword(s):  
Genetic Variation ◽  
Genetic Structure ◽  
Threatened Species ◽  
Population Genetic Structure ◽  
Population Genetic ◽  
Isolation By Distance ◽  
Spatial Genetic Structure ◽  
Population Decline ◽  
Allelic Diversity ◽  
Magdalen Islands

The Gulf of St. Lawrence aster ( Symphyotrichum laurentianum (Fernald) G.L. Nesom) is an endemic annual of saline habitats in the southern Gulf of St. Lawrence. It is listed as a threatened species, and has recently experienced population declines in much of its range. We used 11 allozyme markers to assay population genetic variation in six wild populations of S. laurentianum from the Magdalen Islands, Quebec (QC), the only remaining wild population from Prince Edward Island National Park (PEI), and a greenhouse population founded in 1999 with seed collected from PEI. Symphyotrichum laurentianum harbours moderate genetic diversity (Ps = 0.36, As = 1.54), with only modest spatial genetic structure (pairwise FST < 0.15) and no significant isolation by distance. The PEI population had greatly reduced allelic diversity compared with the populations from the Magdalen Islands, which likely act as a reservoir of genetic variation in S. laurentianum. Recent loss of alleles during population decline in PEI is suggested by the retention of greater allelic diversity in the greenhouse population. Estimates of breeding structure suggest small but nonzero rates of outcross pollination (FIS = 0.73, 95% CI = 0.48–0.97; outcrossing rate ∼16%). Population genetic structure in S. laurentianum can inform those forming and carrying out conservation and recovery plans for this threatened species.

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