Zoospore Motility of Phytophthora cinnamomi in Particulate Substrates

Newhook, F. J.; Young, BR; Allen, S.; Allen, R. N.

doi:10.1111/j.1439-0434.1981.tb03341.x

Cited by 19 publications

(15 citation statements)

References 14 publications

(6 reference statements)

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“…Zentmyer (1980) suggested that this is due to increased infection by zoospores, and our data support this, because following flooding the number of lesions increased while lesion lengths were similar. Zoospores are motile in saturated soil (Duniway, 1976;Newhook et al, 1981) and are chemotactically attracted to ethanol, a product of anaerobically respiring roots (Allen & Newhook, 1973).…”

Section: Discussionmentioning

confidence: 99%

“…Plates were examined for hyphae growing from the root pieces. As the morphology of P. cinnamomi hyphae is distinctive (Newhook, Waterhouse & Stamps, 1978), their identity could be checked with a compound microscope using a X 10 objective. The number of P. cinnamomi colonies was recorded and each segment of root from which the fungus had grown was excised, cut into 1 to 2 cm length pieces, bulked, and the total infected length measured using a Comair root length scanner.…”

Section: Harvesting Proceduresmentioning

confidence: 99%

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THE EFFECT OF WATERLOGGING ON INFECTION OF EUCALYPTUS MARGIN AT A SEEDLINGS BY PHYTOPHTHORA CINNAMOMI

Davison

Tay

1987

New Phytologist

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SUMMARYThree-to four-month-old Eucalyptus marginata Donn ex Sm. (jarrah) were grown in the glasshouse in peat/sand at 20 °C root temperature, infected with zoospores of Phytophthora cinnamomi Rands, added either 10 cm below the soil surface or flooded onto the soil, and various waterlogging regimes were imposed. When plants were infected but not waterlogged, the proportion of infected root length adjacent to the point where zoospores were added was low. More lesions were formed per metre root length on tap roots than on lateral roots, but lesions on lateral roots were longer than on tap roots. When plants were waterlogged for a 4 d period before the addition of zoospores, there was no increase in root infection. When plants were waterlogged at the same time or after the pots were inoculated, there was a significant increase in the proportion of root length infected. This was due to an increase in the number of lesions and not, in four of the five harvests, to an increase in lesion length.When inoculation and waterlogging were imposed at the same time, the increased number of infections was probably due both to the increased attraction of zoospores to anaerobically respiring roots and to increased zoospore motility in flooded soil. When waterlogging was imposed several days or weeks after the plants had been infected, the increased number of lesions was unlikely to have been due to residual zoospores in the soil, because their numbers declined exponentially. It was also unlikely to have been due to sporangia developing de novo on the roots after waterlogging had been imposed, because the Og concentration of the soil solution was inadequate. It is probable, therefore, that the new infections originated from zoospores liberated from sporangia already formed on lesions before waterlogging was imposed.When plants were infected but not waterlogged, there was no efl^ect on the leaf difl^usive resistance, leaf relative water content and shoot xylem pressure potential between 1 and 28 d. When plants were flooded, the daily water loss decreased more rapidly and plants died more rapidly in the inoculated and waterlogged treatments than in the treatments which were only waterlogged. Infection by P. cinnamomi did not aflf^ect the proportion of xylem vessels occluded with tyloses in seven of the eight unflooded, and seven of the eight flooded, comparisons.

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Section: Discussionmentioning

confidence: 99%

Section: Harvesting Proceduresmentioning

confidence: 99%

THE EFFECT OF WATERLOGGING ON INFECTION OF EUCALYPTUS MARGIN AT A SEEDLINGS BY PHYTOPHTHORA CINNAMOMI

Davison

Tay

1987

New Phytologist

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“…The zoosporic phase is of much importance in the infection process, survival and dispersal of plant pathogenic oomycetes (Hickman 1970;Walker and van West 2006;Jeger and Pautasso 2008); yet, what happens to zoospores released from sporangia and failing to target their host remains poorly known (Deacon and Donaldson 1993). Zoospores have a limited capacity for self-dispersal in water films but they can be passively dispersed over long distances by moving water (Newhook et al 1981). In some species of the genera Phytophthora and Pythium, zoospores swim until they encyst permanently or they may display a first swimming period followed by encystment, emergence and a second swimming period followed by encystment, a phenomenon named diplanetism (Drechsler 1930;Dick 2001).…”

Section: Introductionmentioning

confidence: 99%

Diplanetism and microcyclic sporulation in Phytophthora ramorum

Moralejo

Descals

2010

Forest Pathology

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The zoosporic phase of the pathogen Phytophthora ramorum plays a crucial role in the process of plant infection, yet little is known about the fate of zoospores failing to target their hosts. Here, we describe new stages in the life cycle of P. ramorum concerning the in vitro development of monomorphic diplanetism and microcyclic sporulation in free water. Papillate cysts were formed after zoospore suspensions of isolates of the EU1 and NA1 clonal lineages were vortexed. Cysts usually germinated directly forming an emerging tube, or indirectly by releasing a secondary zoospore, which leaves behind an empty cyst with a short evacuation tube. Germinate cysts frequently developed either an appressorium or a microsporangium both terminally. We also observed microcyclic sporulation, i.e. sporangia indirectly germinated by forming a microsporangium, as in microcyclic conidiation of true fungi. Temporal progress of encysted zoospores in solution showed that percentage of germination varied significantly among and within isolates as well as between experiments, suggesting that germination is partly ruled by internal mechanisms. Diplanetism and microcyclic sporulation in P. ramorum may provide a second opportunity for host infection and may increase the chance of long dispersal in moving water.

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“…Zoospores produced from sporangia in moist soil may be passively dispersed by water moving through the profile (Newhook et al, 1981;Shea et al, 1983). Our results suggest that the soil O.^ concentration does not affect the proportion of zoospores which germinate, but does affect their subsequent growth.…”

Section: Effect Of Aeration On Zoospore Germination and Germ Tube Gromentioning

confidence: 72%

THE EFFECT OF AERATION ON COLONY DIAMETER, SPORANGIUM PRODUCTION AND ZOOSPORE GERMINATION OF PHYTOPHTHORA CINNAMOMI

Davison¹,

Tay

1986

New Phytologist

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SUMMARYThe reduced aeration which occurs in waterlogged soil was simulated in the laboratory using O /N gas mixtures, and its effects were studied on six isolates of Phytophthora cinnamomi Rands^. Mycelial growth of five isolates grown on agar under a flowing atmosphere, and sporangium production by all of the isolates grown in bubbled liquid culture, were severely reduced under anaerobic conditions. Three of the isolates showed an increase in the number and rate of development of sporangia with increasing O^ concentration of the gas stream. The other isolates showed no increase in the number of sporangia formed at dissolved Oj concentrations above 13 mg 1"'. There was no efTect of Oj concentration, either during growth (13-5 or 21 % O2) or germination, on the proportion of zoospores that germinated on agar or on initial growth of germ tubes. However, after 19 h, the total length of germ tubes including branches increased with increasing Oj concentration during germination. The number of branches in 11 of the 12 combinations examined was also positively correlated with O2 concentration.

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Zoospore Motility of Phytophthora cinnamomi in Particulate Substrates

Cited by 19 publications

References 14 publications

THE EFFECT OF WATERLOGGING ON INFECTION OF EUCALYPTUS MARGIN AT A SEEDLINGS BY PHYTOPHTHORA CINNAMOMI

THE EFFECT OF WATERLOGGING ON INFECTION OF EUCALYPTUS MARGIN AT A SEEDLINGS BY PHYTOPHTHORA CINNAMOMI

Diplanetism and microcyclic sporulation in Phytophthora ramorum

THE EFFECT OF AERATION ON COLONY DIAMETER, SPORANGIUM PRODUCTION AND ZOOSPORE GERMINATION OF PHYTOPHTHORA CINNAMOMI

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