The Influence of Root Infection by Phytophthora cinnamomi on Mineral Content of Certain Native Species

Phytophthora root rot is a severe disease on blueberry (Vaccinium corymbosum L.) in poorly drained soils. Little is known about how mulching and frequent waterlogging affect disease severity in blueberries. Phytophthora cinnamomi Rands was grown on rice hulls, which were incorporated into the soil at the rate of 10% (v:v). Waterlogging conditions were imposed for 48 hours 1 week after planting on mulched and nonmulched blueberry plants at weekly, biweekly, and monthly intervals for a total of 3 months. Control plants were not subjected to flooding. The severity of Phytophthora root rot increased with time. Significant linear relationships were found between flooding interval and disease severity rating of shoot, percentage of root infection, and shoot and root dry weights of plants. Disease symptoms were minimal in control plants, but shoot disease rating and percentage of root infection were high in mulched and nonmulched plants that were flooded every week. Shoot and root dry weights were higher in 1997 than in 1996. In 1996, mulched plants had higher shoot dry weights than did nonmulched plants. Disease incidence was higher with weekly and biweekly flooding than with monthly or no flooding. However, mulching did not affect root infection.

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

Australian Journal of Botany ◽

10.1071/bt19090 ◽

2019 ◽

Vol 67 (7) ◽

pp. 510 ◽

Cited By ~ 1

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.

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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

Australian Journal of Botany ◽

10.1071/bt96048 ◽

1997 ◽

Vol 45 (1) ◽

pp. 167 ◽

Cited By ~ 11

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.

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Root infection by Phytophthora cinnamomi in seedlings of three oak species

Plant Pathology ◽

10.1046/j.1365-3059.2001.00643.x ◽

2001 ◽

Vol 50 (6) ◽

pp. 708-716 ◽

Cited By ~ 54

Author(s):

C. Robin ◽

G. Capron ◽

M. L. Desprez-Loustau

Keyword(s):

Phytophthora Cinnamomi ◽

Root Infection

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Comparative Pathogenicity of Fourteen Australian Isolates of Phytophthora cinnamomi Determined on Transplants of Tasmanian Temperate Heathland

Australian Journal of Botany ◽

10.1071/bt9890491 ◽

1989 ◽

Vol 37 (6) ◽

pp. 491

Author(s):

FD Podger

Keyword(s):

Root Rot ◽

Native Species ◽

Host Plants ◽

Phytophthora Cinnamomi ◽

Single Plant ◽

Taxonomic Affinity

Peat cores containing mature plants of 21 native species were transplanted from heathland in south- western Tasmania to a greenhouse and inoculated individually with 14 Australian isolates of Phytophthora cinnamomi. The isolates, which had been obtained from 10 different species of host plants and from 14 localities widely distributed across the continent, included three of the four isotypes of the fungus known to occur in Australia. Abnormal coloration, root-rot and death occurred in 9 of the 11 species of dicotyledons present; in a single plant of one species of the 11 monocotyledons but in neither of the two ferns. Of the nine species of dicotyledons in which disease occurred, five species were highly susceptible. Comparisons of the relative pathogenicity of isolates, based on the response of the five highly susceptible species, showed no evidence of strong differences in pathogenicity between groups of isolates, whether these groups were based on isotype of the fungus, climate at the source of the isolates or taxonomic affinity of the host plants from which they were originally isolated.

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Changes in Mineral Content of Eucalyptus marginata and E. calophylla Grown under Controlled Conditions and Inoculated with Phytophthora cinnamomi

Journal of Phytopathology ◽

10.1111/j.1439-0434.1986.tb00890.x ◽

1986 ◽

Vol 116 (1) ◽

pp. 18-29 ◽

Cited By ~ 3

Author(s):

D. Cahill ◽

C. Wookey ◽

G. Weste ◽

J. Rouse

Keyword(s):

Mineral Content ◽

Phytophthora Cinnamomi ◽

Eucalyptus Marginata ◽

Controlled Conditions

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First Report of Root and Crown Rot Caused by Phytophthora cinnamomi Affecting Native Stands of Arctostaphylos myrtifolia and A. viscida in California

Plant Disease ◽

10.1094/pdis.2003.87.11.1395b ◽

2003 ◽

Vol 87 (11) ◽

pp. 1395-1395 ◽

Cited By ~ 7

Author(s):

T. J. Swiecki ◽

E. A. Bernhardt ◽

M. Garbelotto

Keyword(s):

Sierra Nevada ◽

Native Species ◽

Phytophthora Cinnamomi ◽

Crown Rot ◽

Infested Soil ◽

Mixed Stands ◽

First Report ◽

Root And Crown Rot ◽

Dead Plant ◽

Natural Stands

Ione manzanita (Arctostaphylos myrtifolia) is a rare, endemic, evergreen shrub restricted to Ione formation soils (infertile, acidic, sedimentary oxisols) in the foothills of the Sierra Nevada. The widely distributed A. viscida (whiteleaf manzanita) intermixes with A. myrtifolia at the margins of Ione formation soils. In 2002, we observed extensive mortality within two mixed stands of A. myrtifolia and A. viscida near Ione, CA. At one site, nearly all plants of both species in a 0.25-ha area had died recently. At a second site, most of the A. myrtifolia and A. viscida plants on several hectares died at least 5 years earlier. Dying plants of both species exhibited wilting and desiccation of the foliage; dark brown discoloration and necrosis of the root crown, taproot, and some large roots; and loss of fine roots. Plants of all age classes were affected. We consistently isolated a Phytophthora sp. from symptomatic plants of both species using PARP (1) and acidified potato dextrose agar. We recovered the same Phytophthora sp. from soil collected under dead plants using green pears to bait flooded soil samples. The pathogen was not recovered from soil collected under healthy plants 50 m from the nearest dead plant. Based on the morphology of the hyphae, chlamydospores, sporangia, and the sequence of the internal transcribed spacer rDNA, we identified the pathogen as P. cinnamomi Rands (GenBank Accession No. AY267370; ATCC No. MYA-2989). To test pathogenicity, we poured zoospore suspensions (4 × 104 zoospores per pot) on the soil of eight pots with rooted A. myrtifolia cuttings and four pots with rooted A. viscida cuttings (1 14-month-old plant per pot). The soil in inoculated and uninoculated control pots (eight A. myrtifolia and two A. viscida) was flooded for 20 to 23 h. All inoculated A. myrtifolia developed severe root and crown rot, and seven of eight died within 17 days. All inoculated A. viscida developed severe root rot, and three of four developed 5- to 10-cm long basal cankers. After 17 days, we isolated P. cinnamomi from inoculated A. myrtifolia (eight of eight) and A. viscida (two of four) but not from controls, which remained healthy. We tested pathogenicity in native soil by transplanting rooted cuttings (eight A myrtifolia and six A. viscida) into pots of naturally infested soil from one of the disease centers. Controls (four and three plants, respectively) were planted in soil collected from under healthy plants. Pots were flooded for 12 to 13 h for 11 days (A. myrtifolia) or 6 weeks (A. viscida) after transplanting. All plants grown in naturally infested soil developed root and crown rot, and all A. myrtifolia and one A. viscida died within 5 weeks of transplanting. Plants grown in field soil collected near healthy plants remained asymptomatic. We isolated P. cinnamomi from all eight A. myrtifolia and three A. viscida plants grown in infested soil but not from the controls. To our knowledge, this is the first report of root and crown rot caused by P. cinnamomi on A. myrtifolia and A. viscida. P cinnamomi was first isolated in the state in 1942 (2), but it has not previously been reported to caused significant mortality in natural stands of California native species. This disease will significantly impact conservation of the already threatened A. myrtifolia. References: (1) D. C. Erwin and O. K. Ribeiro, Phytophthora Diseases Worldwide. American Phytopathological Society, St. Paul, MN 1996. (2) V. A. Wager. Hilgardia 14:519, 1942.

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Loss of Aggressiveness of Phytophthora cinnamomi (Beta-Cinnamomin Silenced Strain) in the Infection of Castanea sativa

Microscopy and Microanalysis ◽

10.1017/s1431927612012743 ◽

2012 ◽

Vol 18 (S5) ◽

pp. 17-18 ◽

Cited By ~ 2

Author(s):

I. Maia ◽

M. Horta ◽

A. Cravador ◽

C. Medeira

Keyword(s):

Environmental Conditions ◽

Plant Material ◽

Native Species ◽

Forest Decline ◽

Phytophthora Cinnamomi ◽

Castanea Sativa ◽

Forest Species ◽

Living Root ◽

Root Tissues ◽

Ink Disease

Several forest species are severely affected by Phytophthora cinnamomi. The contribution of this oomycete to forest decline and dieback has been broadly reported. In particular, it is consensual that it is the causal agent of ink disease in Castanea sativa. It has been associated with the severe decline of Quercus species, namely the Q. suber and Q. ilex dieback in Portugal and Spain, and has been responsible for the infection of numerous native species and crops. This pathogen persists in the soil or on plant material in the form of chlamydospores allowing the infection of living root tissues when environmental conditions are favorable.

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

Functional Plant Biology ◽

10.1071/fp16266 ◽

2017 ◽

Vol 44 (4) ◽

pp. 386 ◽

Cited By ~ 4

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.

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