scholarly journals Phylogenetic Relationships Among Global Populations of Pseudomonas syringae pv. actinidiae

2012 ◽  
Vol 102 (11) ◽  
pp. 1034-1044 ◽  
Author(s):  
J. R. Chapman ◽  
R. K. Taylor ◽  
B. S. Weir ◽  
M. K. Romberg ◽  
J. L. Vanneste ◽  
...  
Keyword(s):  
New Zealand ◽  
Pseudomonas Syringae ◽  
Phylogenetic Relationships ◽  
Phylogenetic Analyses ◽  
Severe Disease ◽  
Global Distribution ◽  
Disease Symptoms ◽  
Effector Genes ◽  
Evolutionary Trajectories ◽  
Actinidia Spp

Pseudomonas syringae pv. actinidiae, the causal agent of canker in kiwifruit (Actinidia spp.) vines, was first detected in Japan in 1984, followed by detections in Korea and Italy in the early 1990s. Isolates causing more severe disease symptoms have recently been detected in several countries with a wide global distribution, including Italy, New Zealand, and China. In order to characterize P. syringae pv. actinidiae populations globally, a representative set of 40 isolates from New Zealand, Italy, Japan, South Korea, Australia, and Chile were selected for extensive genetic analysis. Multilocus sequence analysis (MLSA) of housekeeping, type III effector and phytotoxin genes was used to elucidate the phylogenetic relationships between P. syringae pv. actinidiae isolates worldwide. Four additional isolates, including one from China, for which shotgun sequence of the whole genome was available, were included in phylogenetic analyses. It is shown that at least four P. syringae pv. actinidiae MLSA groups are present globally, and that marker sets with differing evolutionary trajectories (conserved housekeeping and rapidly evolving effector genes) readily differentiate all four groups. The MLSA group designated here as Psa3 is the strain causing secondary symptoms such as formation of cankers, production of exudates, and cane and shoot dieback on some kiwifruit orchards in Italy and New Zealand. It is shown that isolates from Chile also belong to this MLSA group. MLSA group Psa4, detected in isolates collected in New Zealand and Australia, has not been previously described. P. syringae pv. actinidiae has an extensive global distribution yet the isolates causing widespread losses to the kiwifruit industry can all be traced to a single MLSA group, Psa3.

scholarly journals New Zealand flower thrips and their impact on nectarine fruit diseases

2003 ◽  
Vol 56 ◽  
pp. 157-163
Author(s):  
G.F. McLaren ◽  
J.A. Fraser ◽  
P.A. Alspach
Keyword(s):  
New Zealand ◽  
Pseudomonas Syringae ◽  
Brown Rot ◽  
Bacterial Disease ◽  
Disease Symptoms ◽  
Bacterial Diseases ◽  
Flower Thrips ◽  
Beginning Of Flowering ◽  
Thrips Obscuratus ◽  
The Impact

Insecticides fungicides and a bactericide were applied in spring 2001 and 2002 to nectarine trees to determine the impact of thrips (mainly New Zealand flower thrips Thrips obscuratus) on summerfruit pathogens Thrips numbers were assessed over 7 weeks from the beginning of flowering The insecticide programme increased the proportion of fruit meeting export standards for thrips damage but did not influence the level of either brown rot caused by Monilinia fructicola or the bacterial diseases bacterial blast (Pseudomonas syringae) and bacterial spot (Xanthomonas arboricola pv pruni) The fungicide programme reduced the level of brown rot Cumulative thrips counts were positively correlated with levels of brown rot infection on the fruit at harvest time in 2001/02 (P002) and 2002/03 (P009) and bacterial disease symptoms in 2001/ 02 (P003) It was concluded that New Zealand flower thrips could increase levels of disease in nectarines but the value of treating with insecticides was not clear

scholarly journals Phylogenetic analyses using molecular markers reveal ecological lineages in Medetera (Diptera: Dolichopodidae)

2011 ◽  
Vol 143 (6) ◽  
pp. 662-673 ◽  
Author(s):  
Marc Pollet ◽  
Christoph Germann ◽  
Marco Valerio Bernasconi
Keyword(s):  
Molecular Markers ◽  
Phylogenetic Relationships ◽  
Phylogenetic Analyses ◽  
Sister Group ◽  
Species Group ◽  
Global Distribution ◽  
Sister Group Relationship ◽  
Mitochondrial Coi ◽  
Terrestrial Habitats

AbstractMedetera Fischer von Waldheim is the most speciose genus in the Medeterinae, with a nearly ubiquitous global distribution. Phylogenetic relationships within Medetera and between Medetera and four other medeterine genera were investigated using mitochondrial (COI, 16S) and nuclear (18S) markers to test morphological hypotheses. Our results confirm most of Bickel's hypotheses. Thrypticus Gerstäcker shows a sister-group relationship with Medetera + Dolichophorus Lichtwardt. The Medetera species included here split into two clades. One clade corresponds to the M. diadema L. – veles Loew species group sensu Bickel. The second clade is largely composed of the M. apicalis (Zetterstedt) species group sensu Bickel and the M. aberrans Wheeler species group sensu Bickel + Dolichophorus. Although most Medeterinae are associated with plants (mainly trees), species in at least two separate lineages demonstrate a secondary return to terrestrial habitats. The implication of this evolutionary phenomenon is briefly discussed.

scholarly journals Protection of Arabidopsis thaliana against Leaf-Pathogenic Pseudomonas syringae by Sphingomonas Strains in a Controlled Model System

2011 ◽  
Vol 77 (10) ◽  
pp. 3202-3210 ◽  
Author(s):  
Gerd Innerebner ◽  
Claudia Knief ◽  
Julia A. Vorholt
Keyword(s):  
Arabidopsis Thaliana ◽  
Pseudomonas Syringae ◽  
Plant Protection ◽  
Severe Disease ◽  
Model System ◽  
Tomato Dc3000 ◽  
Disease Symptoms ◽  
Content Type ◽  
Cell Densities ◽  
Symptom Formation

ABSTRACTDiverse bacterial taxa live in association with plants without causing deleterious effects. Previous analyses of phyllosphere communities revealed the predominance of few bacterial genera on healthy dicotyl plants, provoking the question of whether these commensals play a particular role in plant protection. Here, we tested two of them,MethylobacteriumandSphingomonas, with respect to their ability to diminish disease symptom formation and the proliferation of the foliar plant pathogenPseudomonas syringaepv. tomato DC3000 onArabidopsis thaliana. Plants were grown under gnotobiotic conditions in the absence or presence of the potential antagonists and then challenged with the pathogen. No effect ofMethylobacteriumstrains on disease development was observed. However, members of the genusSphingomonasshowed a striking plant-protective effect by suppressing disease symptoms and diminishing pathogen growth. A survey of differentSphingomonasstrains revealed that most plant isolates protectedA. thalianaplants from developing severe disease symptoms. This was not true forSphingomonasstrains isolated from air, dust, or water, even when they reached cell densities in the phyllosphere comparable to those of the plant isolates. This suggests that plant protection is common among plant-colonizingSphingomonasspp. but is not a general trait conserved within the genusSphingomonas. The carbon source profiling of representative isolates revealed differences between protecting and nonprotecting strains, suggesting that substrate competition plays a role in plant protection bySphingomonas. However, other mechanisms cannot be excluded at this time. In conclusion, the ability to protect plants as shown here in a model system may be an unexplored, common trait of indigenousSphingomonasspp. and may be of relevance under natural conditions.

scholarly journals The Pseudomonas syringae avrRpt2 Gene Product Promotes Pathogen Virulence from Inside Plant Cells

2000 ◽  
Vol 13 (12) ◽  
pp. 1312-1321 ◽  
Author(s):  
Zhongying Chen ◽  
Andrew P. Kloek ◽  
Jens Boch ◽  
Fumiaki Katagiri ◽  
Barbara N. Kunkel
Keyword(s):  
Pseudomonas Syringae ◽  
Severe Disease ◽  
Plant Cells ◽  
R Gene ◽  
Disease Symptoms ◽  
Pathogen Virulence ◽  
Enhanced Resistance ◽  
Mutant Lines ◽  
Avr Genes

Several bacterial avr genes have been shown to contribute to virulence on susceptible plants lacking the corresponding resistance (R) gene. The mechanisms by which avr genes promote parasitism and disease, however, are not well understood. We investigated the role of the Pseudomonas syringae pv. tomato avrRpt2 gene in pathogenesis by studying the interaction of P. syringae pv. tomato strain PstDC3000 expressing avrRpt2 with several Arabidopsis thaliana lines lacking the corresponding R gene, RPS2. We found that PstDC3000 expressing avrRpt2 grew to significantly higher levels and often resulted in the formation of more severe disease symptoms in ecotype No-0 plants carrying a mutant RPS2 allele, as well as in two Col-0 mutant lines, cpr5 rps2 and coi1 rps2, that exhibit enhanced resistance. We also generated transgenic A. thaliana lines expressing avrRpt2 and demonstrated, by using several different assays, that expression of avrRpt2 within the plant also promotes virulence of PstDC3000. Thus, AvrRpt2 appears to promote pathogen virulence from within the plant cell.

scholarly journals A Phylogenetic Investigation of the New Zealand  Pteridaceae Ferns

2021 ◽  
Author(s):  
◽  
Whitney L M Bouma
Keyword(s):  
New Zealand ◽  
Dna Sequences ◽  
Phylogenetic Relationships ◽  
Native Species ◽  
Sequence Data ◽  
Phylogenetic Analyses ◽  
Morphological Characters ◽  
Taxonomic Confusion ◽  
Species Specific

<p>The fern family Pteridaceae is among the largest fern families in New Zealand. It comprises 17 native species among five genera. Traditionally the classification of Pteridaceae was based on morphological characters. The advent of molecular technology, now makes is possible to test these morphology-based classifications. The Pteridaceae has previously been subjected to phylogenetic analyses; however representatives from New Zealand and the South Pacific have never been well represented in these studies. This thesis research aimed to investigate the phylogenetic relationships of the New Zealand Pteridaceae, as well as, the phylogenetic relationships of the New Zealand species to their overseas relatives. The DNA sequences of several Chloroplast loci (e.g. trnL-trnF locus, rps4 and rps4-trnS IGS, atpB, and rbcL) were determined and the phylogenetic relationships of the New Zealand Pteridaceae and several species-specific question within the genus Pellaea and Adiantum were investigated. Results presented in this thesis confirm previously published phylogenetics of the Pteridaceae, which show the resolution of five major clades, i.e.,cryptogrammoids, ceratopteridoids, pteridoids, cheilanthoids, and the adiantoids. The addition of the New Zealand species revealed a possible South West Pacific groups formed by the respective genera, where New Zealand species were generally more related to one another than to overseas relatives. Within the New Zealand Pellaea, the analysis of the trnL-trnF locus sequence data showed that the morphologically-intermediate plants P. aff. falcata, responsible for taxonomic confusion, were more closely related to P. rotundifolia than to P. falcata. Furthermore, the species collected on the Kermadec Islands, previously thought to be P. falcata, are genetically distinct from the Australian P. falcata and they could constitute a new species. Adiantum hispidulum, which is polymorphic for two different hair types being used to distinguish them as different species, was also reinvestigated morphologically and molecularly. Morphological inspection of hairs revealed three hair types as opposed to the previous thought two, and furthermore, they correspond to three different trnL-trnF sequences haplotypes.</p>

scholarly journals Survival of Pseudomonas syringae pv actinidiae on the orchard floor over winter

2012 ◽  
Vol 65 ◽  
pp. 25-28 ◽  
Author(s):  
J.L. Tyson ◽  
J. Rees-George ◽  
C.L. Curtis ◽  
M.A. Manning ◽  
R.A. Fullerton
Keyword(s):  
New Zealand ◽  
Leaf Litter ◽  
Pseudomonas Syringae ◽  
Inoculum Source ◽  
Detection Frequency ◽  
Fallen Leaves ◽  
Actinidia Spp ◽  
Over Time

Pseudomonas syringae pv actinidiae (Psa) was first identified on kiwifruit (Actinidia spp) in New Zealand in November 2010 and has since caused serious losses particularly in Te Puke The role of fallen leaves and pruning debris in the lifecycle of Psa in New Zealand is unknown Survival of Psa was investigated in fallen leaves and cane prunings over winter 2011 Heavily infected leaves and cane prunings with Psa dieback symptoms were kept on the orchard floor and in the laboratory and assayed weekly for the presence of viable Psa At leaffall all leaves yielded live Psa Although detection frequency declined over time especially after 56 weeks Psa was still isolated from leaf litter 15 weeks after leaffall and cane prunings 11 weeks after winter pruning These results indicate that the pathogen overwinters readily in leaf litter and pruning debris representing a potential inoculum source for infection of new spring growth

scholarly journals An avrPto/avrPtoB Mutant of Pseudomonas syringae pv. tomato DC3000 Does Not Elicit Pto-Mediated Resistance and Is Less Virulent on Tomato

2005 ◽  
Vol 18 (1) ◽  
pp. 43-51 ◽  
Author(s):  
Nai-Chun Lin ◽  
Gregory B. Martin
Keyword(s):  
Pseudomonas Syringae ◽  
Double Mutant ◽  
Deletion Mutant ◽  
Severe Disease ◽  
Defense Responses ◽  
Effector Proteins ◽  
Avirulence Genes ◽  
Disease Symptoms ◽  
Tomato Plants ◽  
Susceptible Tomato

AvrPto and AvrPtoB are type III effector proteins expressed by Pseudomonas syringae pv. tomato strain DC3000, a pathogen of both tomato and Arabidopsis spp. Each effector physically interacts with the tomato Pto kinase and elicits a hypersensitive response when expressed in tomato leaves containing Pto. An avrPto deletion mutant of DC3000 previously was shown to retain avirulence activity on Pto-expressing tomato plants. We developed an avrPtoB deletion mutant of DC3000 and found that it also retains Pto-specific avirulence on tomato. These observations suggested that avrPto and avrPtoB both contribute to avirulence. To test this hypothesis, we developed an ΔavrPtoΔavrPtoB double mutant in DC3000. This double mutant was able to cause disease on a Pto-expressing tomato line. Thus, avrPto and avrPtoB are the only avirulence genes in DC3000 that elicit Pto-mediated defense responses in tomato. When inoculated onto susceptible tomato leaves and compared with wild-type DC3000, the mutants DC3000ΔavrPto and DC3000ΔavrPtoB each caused slightly less severe disease symptoms, although their growth rate was unaffected. However, DC3000ΔavrPtoΔavrPtoB caused even less severe disease symptoms than the single mutants and grew more slowly than them on susceptible leaves. Our results indicate that AvrPto and AvrPtoB have phenotypically redundant avirulence activity on Pto-expressing tomato and additive virulence activities on susceptible tomato plants.

scholarly journals A Phylogenetic Investigation of the New Zealand  Pteridaceae Ferns

2021 ◽  
Author(s):  
◽  
Whitney L M Bouma
Keyword(s):  
New Zealand ◽  
Dna Sequences ◽  
Phylogenetic Relationships ◽  
Native Species ◽  
Sequence Data ◽  
Phylogenetic Analyses ◽  
Morphological Characters ◽  
Taxonomic Confusion ◽  
Species Specific

<p>The fern family Pteridaceae is among the largest fern families in New Zealand. It comprises 17 native species among five genera. Traditionally the classification of Pteridaceae was based on morphological characters. The advent of molecular technology, now makes is possible to test these morphology-based classifications. The Pteridaceae has previously been subjected to phylogenetic analyses; however representatives from New Zealand and the South Pacific have never been well represented in these studies. This thesis research aimed to investigate the phylogenetic relationships of the New Zealand Pteridaceae, as well as, the phylogenetic relationships of the New Zealand species to their overseas relatives. The DNA sequences of several Chloroplast loci (e.g. trnL-trnF locus, rps4 and rps4-trnS IGS, atpB, and rbcL) were determined and the phylogenetic relationships of the New Zealand Pteridaceae and several species-specific question within the genus Pellaea and Adiantum were investigated. Results presented in this thesis confirm previously published phylogenetics of the Pteridaceae, which show the resolution of five major clades, i.e.,cryptogrammoids, ceratopteridoids, pteridoids, cheilanthoids, and the adiantoids. The addition of the New Zealand species revealed a possible South West Pacific groups formed by the respective genera, where New Zealand species were generally more related to one another than to overseas relatives. Within the New Zealand Pellaea, the analysis of the trnL-trnF locus sequence data showed that the morphologically-intermediate plants P. aff. falcata, responsible for taxonomic confusion, were more closely related to P. rotundifolia than to P. falcata. Furthermore, the species collected on the Kermadec Islands, previously thought to be P. falcata, are genetically distinct from the Australian P. falcata and they could constitute a new species. Adiantum hispidulum, which is polymorphic for two different hair types being used to distinguish them as different species, was also reinvestigated morphologically and molecularly. Morphological inspection of hairs revealed three hair types as opposed to the previous thought two, and furthermore, they correspond to three different trnL-trnF sequences haplotypes.</p>

Effect of a protectant copper application on Psa infection of kiwifruit trap plants

2017 ◽  
Vol 70 ◽  
pp. 310-314
Author(s):  
J.L. Tyson ◽  
S.J. Dobson ◽  
M.A. Manning
Keyword(s):  
New Zealand ◽  
Disease Control ◽  
Pseudomonas Syringae ◽  
Low Risk ◽  
Bacterial Canker ◽  
Complete Protection ◽  
Leaf Spots ◽  
Copper Compounds ◽  
Trap Plants

Pseudomonas syringae pv. actinidiae (Psa) causes bacterial canker of kiwifruit, which is an ongoing threat to New Zealand kiwifruit production. Disease control depends on orchard practices such as removal of visibly diseased material, pruning during low-risk periods, and the application of foliar bactericides. Although the use of copper compounds on Actinidia species (kiwifruit) can cause phytotoxicity, copper-based formulations remain a key component of Psa control in New Zealand. The effect of single copper applications on Psa infection of ‘Hort16A’ trap plants was studied over the Spring of 2014 (Sept—Nov). Psa leaf spots were observed at the beginning of October, appearing first on the untreated plants. Although the copper sprays did not achieve complete protection, particularly as the inoculum built up during November, the copper-sprayed plants always had less disease than the untreated plants.

scholarly journals Linking morphological and molecular sources to disentangle the case of Xylodon australis

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Javier Fernández-López ◽  
M. Teresa Telleria ◽  
Margarita Dueñas ◽  
Mara Laguna-Castro ◽  
Klaus Schliep ◽  
...  
Keyword(s):  
New Zealand ◽  
Phylogenetic Analyses ◽  
Single Species ◽  
R Package ◽  
Molecular Data ◽  
Historical Collections ◽  
Close Relationship ◽  
Kinship Relations ◽  
History Of ◽  
Different Sources

AbstractThe use of different sources of evidence has been recommended in order to conduct species delimitation analyses to solve taxonomic issues. In this study, we use a maximum likelihood framework to combine morphological and molecular traits to study the case of Xylodon australis (Hymenochaetales, Basidiomycota) using the locate.yeti function from the phytools R package. Xylodon australis has been considered a single species distributed across Australia, New Zealand and Patagonia. Multi-locus phylogenetic analyses were conducted to unmask the actual diversity under X. australis as well as the kinship relations respect their relatives. To assess the taxonomic position of each clade, locate.yeti function was used to locate in a molecular phylogeny the X. australis type material for which no molecular data was available using morphological continuous traits. Two different species were distinguished under the X. australis name, one from Australia–New Zealand and other from Patagonia. In addition, a close relationship with Xylodon lenis, a species from the South East of Asia, was confirmed for the Patagonian clade. We discuss the implications of our results for the biogeographical history of this genus and we evaluate the potential of this method to be used with historical collections for which molecular data is not available.

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