Active defence by an Australian native host, Lomandra longifolia, provides resistance against Phytophthora cinnamomi

2017 ◽  
Vol 44 (4) ◽  
pp. 386 ◽  
Author(s):  
Md Tohidul Islam ◽  
James E. Rookes ◽  
David M. Cahill
Keyword(s):  
Native Species ◽  
Phytophthora Cinnamomi ◽  
Lesion Length ◽  
Root Pathogen ◽  
Resistant Species ◽  
Multiple Components ◽  
Whole Plant ◽  
Active Defence ◽  
Callose Formation ◽  
Native Host

Resistance is rare against the oomycete plant pathogen Phytophthora cinnamomi Rands. Only a limited number of species have been recorded as field-resistant species in Australia. However, understanding the nature of resistance of those species when grown under controlled conditions is challenging because of their slow growth and the inherent difficulties of working with a root pathogen. We assessed the Australian native species, Lomandra longifolia Labill., as a resistant species by analysing in detail the response of roots to infection by P. cinnamomi in a series of comparative tests with Lupinus angustifolius L., a highly susceptible species. Following inoculation of L. longifolia roots, lesion length and colonisation percentage were significantly less than in roots of the susceptible species. Moreover, there was no statistical difference in root growth rate, whole-plant FW and leaf relative chlorophyll content between controls and inoculated L. longifolia. We then examined three key cellular responses that are related to resistance: the production of the reactive oxygen species, H2O2, callose formation and lignin deposition in L. longifolia roots following inoculation with P. cinnamomi. The upregulation of these resistance-related components in the early hours after inoculation suggested their involvement in resistance and that this is controlled by the coordinated response of multiple components. Resistance assessment and a detailed investigation of cellular resistance components along with gene expression analysis provides a platform for further understanding of the mechanisms of resistance against this generalist pathogen and presents opportunities for manipulating susceptible species for disease resistance.

Endangered Butterflies and their Non-Native Host Plants: Examining Shifting Values of Belonging in Restoration

2019 ◽  
Vol 3 (1) ◽  
pp. 1-9
Author(s):  
Robert M. Anderson ◽  
Amy M. Lambert
Keyword(s):  
Ecological Restoration ◽  
Native Species ◽  
Puget Sound ◽  
A Value ◽  
The Social ◽  
Remote Island ◽  
Scientific Truth ◽  
Native Host

The island marble butterfly (Euchloe ausonides insulanus), thought to be extinct throughout the 20th century until re-discovered on a single remote island in Puget Sound in 1998, has become the focus of a concerted protection effort to prevent its extinction. However, efforts to “restore” island marble habitat conflict with efforts to “restore” the prairie ecosystem where it lives, because of the butterfly’s use of a non-native “weedy” host plant. Through a case study of the island marble project, we examine the practice of ecological restoration as the enactment of particular norms that define which species are understood to belong in the place being restored. We contextualize this case study within ongoing debates over the value of “native” species, indicative of deep-seated uncertainties and anxieties about the role of human intervention to alter or manage landscapes and ecosystems, in the time commonly described as the “Anthropocene.” We interpret the question of “what plants and animals belong in a particular place?” as not a question of scientific truth, but a value-laden construct of environmental management in practice, and we argue for deeper reflexivity on the part of environmental scientists and managers about the social values that inform ecological restoration.

Acetolactate Synthase Resistance in a Common Waterhemp (Amaranthus rudis) Population

1997 ◽  
Vol 11 (1) ◽  
pp. 13-18 ◽  
Author(s):  
John R. R. Hinz ◽  
Micheal D. K. Owen
Keyword(s):  
Plant Material ◽  
Resistance Mechanism ◽  
Acetolactate Synthase ◽  
Grain Amaranth ◽  
Common Waterhemp ◽  
Resistant Species ◽  
Whole Plant ◽  
Amaranthus Rudis ◽  
Inhibitor Resistance ◽  
Als Inhibitor

Research was initiated to determine (a) whether a common waterhemp population was resistant to acetolactate synthase (ALS) inhibiting herbicides, (b) the percentage of the population that was ALS-inhibitor resistant, (c) the resistance mechanism, and (d) the effectiveness of a whole plant assay to detect ALS-inhibitor resistance. ALS-inhibitor resistance was confirmed in a common waterhemp population near Davis City, IA. The Davis City common waterhemp population was cross resistant to both imidazolinone and sulfonylurea herbicides, but not to lactofen. Approximately 10% of the Davis City common waterhemp population was sensitive to a rate of imazaquin 4 times the normal field rate. Davis City common waterhemp isolated ALS was much less sensitive to imazaquin and primisulfuron inhibition than was grain amaranth or an ALS-sensitive common waterhemp isolated ALS. Imazaquin I50values were 366.4 and 3.4 μM for ALS isolated from Davis City common waterhemp and grain amaranth, respectively. Primisulfuron I50values were 3.6 and 0.007 μM for ALS isolated from Davis City common waterhemp and grain amaranth, respectively. A whole plant ALS assay was developed that allowed for much more rapid detection of an ALS-resistant species and used less plant material than a conventional ALS assay.

The susceptibility of rare and threatened NSW species to the root-rot pathogen Phytophthora cinnamomi: 1. Initial testing and identification of key research questions

2019 ◽  
Vol 67 (7) ◽  
pp. 510 ◽  
Author(s):  
Justin S. H. Wan ◽  
Keith L. McDougall ◽  
Edward C. Y. Liew
Keyword(s):  
Threatened Species ◽  
Native Species ◽  
Prophylactic Treatment ◽  
Phytophthora Cinnamomi ◽  
New South ◽  
South Wales ◽  
Disease Aetiology ◽  
Susceptible Control ◽  
Research Questions ◽  
Pathogen Recovery

In Australia disease caused by Phytophthora cinnamomi can have devastating impacts on native vegetation, especially on plant species with restricted distributions. The identification of susceptible threatened species is a crucial first step in understanding disease aetiology and selecting appropriate management. In a glasshouse trial, plants of 16 rare and threatened New South Wales native species from 10 families were inoculated with the pathogen. Phebalium squamulosum spp. alpinum was included as a susceptible control. We found that three species are highly susceptible to the pathogen (Nematolepis rhytidophylla (Albr. & N.G.Walsh) Paul G.Wilson, Prostanthera marifolia R.Br., Pultenaea sp. ‘Genowlan Point’); four others (Hibbertia spanantha Toelken & A.F.Rob, Phebalium bifidum P.H.Weston & M.J.Turton, Plinthanthesis rodwayi (C.E.Hubb.) S.T.Blake, Pomaderris delicata N.G.Walsh & Coates) are likely to be susceptible based on symptoms. The remaining species had few or no plant deaths and no pathogen recovery from the roots. All of the species regarded as highly susceptible are known from single populations. Following these results, subsequent research will assess the efficacy of prophylactic treatment on highly susceptible threatened species, and test whether glasshouse tests are indicative of field responses. Other threatened species will also be tested for susceptibility.

Vegetation Changes Associated With Invasion by Phytophthora cinnamomi of Defined Plots in the Brisbane Ranges, Victoria, 1975-1985

1986 ◽  
Vol 34 (6) ◽  
pp. 633 ◽  
Author(s):  
G Weste
Keyword(s):  
Slow Growth ◽  
Phytophthora Cinnamomi ◽  
Vegetation Changes ◽  
Bare Ground ◽  
Shrub Species ◽  
Slow Growth Rate ◽  
Ground Flora ◽  
Resistant Species ◽  
Open Forest ◽  
Vigorous Growth

Changes in plant species composition over a 10 year period were measured by biennial counts of numbers and areas on seven quadrats at each of three sites; one site pathogen free, one in the process of invasion by Phytophthora cinnamomi and one diseased since 1970. Susceptible species died and field-resistant species increased. Partly susceptible species fluctuated in growth. The plant community changed from open forest with sclerophyllous understorey dominated by Xanthorrhoea australis to open forest with large gaps and sedge-dominated ground flora. Tree numbers increased by 25% on the pathogen-free site but decreased by 42.9 and 45.3% on the two infested sites. Susceptible shrub species increased 10% on pathogen-free quadrats but decreased in both numbers and diversity with infestation. The high percentage of bare ground on the old diseased site was gradually colonised by graminoids and legumes. At the end of the 10 year period P. cinnamomi could no longer be isolated from this site, tree crowns showed vigorous growth and seedlings of some susceptible species were observed. The epidemic caused by P. cinnamomi in the Brisbane Ranges may be finite, with peak death periods in 1979 for the invaded site and in 1972 for the old diseased site. The bare ground was later colonised by field-resistant species and the disease potential of the pathogen declined. Regeneration has commenced on the old diseased site and may eventually become complete for the tree stratum, but incomplete for the understorey because Xanthorrhoea australis, formerly dominant, has a very slow growth rate.

Regeneration of Susceptible Native Species Following a Decline of Phytophthora cinnamomi over a Period of 20 Years on Defined Plots in the Grampians, Western Victoria

1997 ◽  
Vol 45 (1) ◽  
pp. 167 ◽  
Author(s):  
Gretna Weste ◽  
Jill Kennedy
Keyword(s):  
Species Composition ◽  
Plant Communities ◽  
Native Species ◽  
Phytophthora Cinnamomi ◽  
Susceptible Host ◽  
Open Forest ◽  
Crown Density ◽  
Set Up ◽  
Pathogen Populations ◽  
Western Victoria

Regeneration of susceptible species following a major decline in the population and distribution of the pathogen Phytophthora cinnamomi Rands is reported from a reassessment of infested plots in open forest, woodland and heathland of the Grampians. The distribution of P. cinnamomi and changes in the vegetation were measured on quadrats set up in 1976 and 1977 and checked biennially until 1984. In 1995, P. cinnamomi was detected in only 15.6% of the 345 soil and root samples tested and was present in only 28.6% of the infested quadrats compared with 100% of the samples and infested quadrats in all previous assessments. Both the restricted distribution and the isolation of P. cinnamomi from susceptible species without symptoms were evidence of changes in the disease which may have been associated with factors such as a reduced supply of susceptible host roots or an alteration in pathogenicity or in the environment. Changes were recorded in structure and species composition of infested plant communities compared with those that remained pathogen-free, but few recent deaths or dieback symptoms were observed in 1995. On the infested plots, several mature stringybark eucalypts such as Eucalyptus baxteri and E. obliqua had died, and the survivors had reduced crown density and dieback of the major branches. However, regeneration in the form of 8-year-old saplings and young seedlings showed few or no symptoms despite the isolation of P. cinnamomi from the roots. The understorey of infested plots comprised a dense growth of field-resistant plants such as Leptospermum spp. and sedges entwined with dodder laurel, whereas the uninfested plots contained a species-rich heath flora of which 54% were known to be susceptible to P. cinnamomi. Regeneration and continuing survival of 24 susceptible species from 11 different families were recorded as small plants on various infested quadrats. However, 12 susceptible species from 7 different families had failed to regenerate. Pathogen populations may increase with the renewed supply of susceptible roots, but independent of pathogen potential, the emerging susceptible species may not be able to compete effectively against the dense field-resistant understorey in infested plots in order to re-establish the original diverse heathland understorey.

The invasion of native forest by Phytophthora cinnamomi. I. Brisbane Ranges, Victoria

1971 ◽  
Vol 19 (3) ◽  
pp. 281 ◽  
Author(s):  
GM Weste ◽  
P Taylor
Keyword(s):  
Water Stress ◽  
Phytophthora Cinnamomi ◽  
Eucalyptus Species ◽  
Native Forest ◽  
Symptom Expression ◽  
Root Pathogen ◽  
Disease Symptoms ◽  
Sclerophyll Forest ◽  
Drainage Channels

Disease within an open sclerophyll forest dominated by Eucalyptus species of relatively low stature (15-20 m) was shown to be caused by Phytophthora cinnamomi Rands, an introduced root pathogen. Diseased sites were mapped and measured. The rate of advance of the pathogen over a period of 5 months was calculated at 4 m per month through moderately drained soils compared with 7 m per month through soils subject to waterlogging. Areas showing disease symptoms increased from 10.8 to 90%, the major extensions occurring along gullies. Spread of the fungus was associated with road-making activities, waterlogging, and the presence of drainage channels. Symptom expression in the different species was studied and shown to be similar to that associated with water stress. Most of the 42 species comprising the woody flora were susceptible to the disease, those particularly susceptible including the dominants. During a period of 8 months mortalities occurred in 50% of the species. Grasses, sedges, and Eucalyptus goniocalyx appeared to be field-resistant, but were uncommon in the Aora of the sites studied.

scholarly journals Screening Cotoneaster for Resistance to Fire Blight by Artificial Inoculation

HortScience ◽  
2014 ◽  
Vol 49 (12) ◽  
pp. 1480-1485 ◽  
Author(s):  
Joseph J. Rothleutner ◽  
Ryan N. Contreras ◽  
Virginia O. Stockwell ◽  
James S. Owen
Keyword(s):  
Disease Resistance ◽  
Fire Blight ◽  
Bacterial Pathogen ◽  
Artificial Inoculation ◽  
Lesion Length ◽  
Sources Of Resistance ◽  
Landscape Plants ◽  
Whole Plant ◽  
Wide Range ◽  
Disease Pressure

Cotoneaster Medik. is a genus of ornamental landscape plants commonly affected by fire blight. Fire blight is a disease caused by the bacterial pathogen, Erwinia amylovora (Burrill) Winslow et al., that attacks a wide range of taxa in the apple subfamily (Maloideae; Rosaceae). To assess susceptibility of species and identify potential sources of resistance, we inoculated 52 taxa of Cotoneaster with E. amylovora. Disease severity was scored by percent shoot necrosis (lesion length/total shoot length). Disease screenings were conducted over 2 years and varying levels of susceptibility were observed. Some taxa were highly susceptible to fire blight and the disease resulted in whole plant mortality (C. rhytidophyllus Rehder & E.H. Wilson, C. rugosus E. Pritzel ex Diels, and C. wardii W.W. Smith). Other taxa repeatedly exhibited moderate to high levels of disease resistance [C. arbusculus G. Klotz, C. chungtinensis (T.T. Yu) J. Fryer & B. Hylmö, C. delsianus E. Pritzel var. delsianus, C. sikangensis Flinck & B. Hylmö, C. simonsii Baker, and C. splendens Flinck & Hylmö]. Ongoing studies are being conducted to determine if taxa with high levels of resistance under artificial inoculation will exhibit high levels of resistance in the field under natural disease pressure. Identifying sources of disease resistance will be useful for breeding programs to increase tolerance of these landscape plants with desirable horticultural characteristics to fire blight.

A Comparison of Phytophthora cinnamomi Infection in Eucalyptus sieberi, a Susceptible Species, and Eucalyptus maculata a Field Resistant Species

1978 ◽  
Vol 26 (5) ◽  
pp. 643 ◽  
Author(s):  
DM Halsall
Keyword(s):  
Root Growth ◽  
Shoot Growth ◽  
Phytophthora Cinnamomi ◽  
Growth Reduction ◽  
Resistant Species ◽  
Eucalypt Species ◽  
Root And Shoot Growth ◽  
Seedling Roots ◽  
Eucalyptus Maculata

Zoospores of Phytophthora cinnamomi Rands were attracted, in almost equal numbers, to seedling roots of Eucalyptus sieberi (a susceptible species) and Eucalyptus maculata (a field resistant species). Germinating zoospores penetrated and mycelium developed within seedling roots of both species. The root and shoot growth of both eucalypt species were reduced by P. cinnamomi infection. In E. sieberi the growth reduction was greater than in E. maculata seedlings and other symptoms of infection were evident. Cell-free extracts of P. cinnamomi were able to produce some of the symptoms of infection in the absence of parasitism. Root growth of both eucalypt species was reduced at high extract dilutions and seedling deaths occurred at low extract dilutions.

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