02914nas a2200205 4500008004100000022001400041245009700055210006900152260002900221300001400250490000700264520228600271100001502557700001202572700001702584700001602601700001402617700002202631856005502653 2011 eng d a1439-032900aPathogenicity of Phytophthora multivora to Eucalyptus gomphocephala and Eucalyptus marginata0 aPathogenicity of Phytophthora multivora to Eucalyptus gomphoceph bBlackwell Publishing Ltd a289–2980 v423 a

Phytophthora multivora is associated with the rhizosphere of declining Eucalyptus gomphocephala, Eucalyptus marginata and Agonis flexuosa. Two pathogenicity experiments were conducted. The first experiment examined the pathogenicity of five P. multivora isolates and one Phytophthora cinnamomi isolate on the root systems of E. gomphocephala and one P. multivora isolate on the root system of E. marginata. In the second experiment, the pathogenicity of P. multivora to E. gomphocephala and E. marginata saplings was measured using under-bark stem inoculation. In Experiment 1, the P. cinnamomi isolate was more aggressive than all P. multivora isolates causing significant loss of fine roots and plant death. Two P. multivora isolates and the P. cinnamomi isolate caused significant losses of E. gomphocephala fine roots 0-2 mm in diameter and significantly reduced the surface area of roots 0-1 mm in diameter. One P. multivora and the P. cinnamomi isolate significantly reduced the surface area of roots 1-2 mm in diameter. Two of the P. multivora isolates significantly reduced the number of E. gomphocephala root tips. In E. marginata, the length and surface area of roots 0-1 mm in diameter and number of root tips were significantly reduced by P. multivora infestation. Rhizosphere infestation with the P. multivora isolates and P. cinnamomi isolate on E. gomphocephala, and one P. multivora isolate on E. marginata, did not significantly influence the foliar nutrient concentrations. In Experiment 2, under-bark inoculation with P. multivora caused significant lesion extension in E. gomphocephala and E. marginata saplings, compared to the control. We propose that P. multivora is inciting E. gomphocephala and E. marginata decline by causing fine root loss and subsequently interfering with nutrient cycling throughout the plant. The impact of fine root loss on the physiology of plants in sites infested with P. multivora requires further research.

1 aScott, P M1 aJung, T1 aShearer, B L1 aBarber, P A1 aCalver, M1 aHardy, St., G E J uhttp://dx.doi.org/10.1111/j.1439-0329.2011.00753.x01615nas a2200193 4500008004100000245014900041210006900190300001300259490000700272520096800279100001501247700001701262700001601279700001701295700001901312700002101331700001201352856005701364 2009 eng d00aPhytophthora multivora sp. nov., a new species recovered from declining Eucalyptus, Banksia, Agonis and other plant species in Western Australia0 aPhytophthora multivora sp nov a new species recovered from decli a1-13(13)0 v223 a

A new Phytophthora species, isolated from rhizosphere soil of declining or dead trees of Eucalyptus gomphocephala, E. marginata, Agonis flexuosa, and another 13 plant species, and from fine roots of E. marginata and collar lesions of Banksia attenuata in Western Australia, is described as Phytophthora multivora sp. nov. It is homothallic and produces semipapillate sporangia, smooth-walled oogonia containing thick-walled oospores, and paragynous antheridia. Although morphologically similar to P. citricola, phylogenetic analyses of the ITS and cox1 gene regions demonstrate that P. multivora is unique. Phytophthora multivora is pathogenic to bark and cambium of E. gomphocephala and E. marginata and is believed to be involved in the decline syndrome of both eucalypt species within the tuart woodland in south-west Western Australia.

1 aScott, P M1 aBurgess, T I1 aBarber, P A1 aShearer, B L1 aStukely, M J C1 aHardy, G.E.St.J.1 aJung, T uhttp://www.ncbi.nlm.nih.gov/pmc/articles/PMC2789538/