During routine surveys of Pinus radiata plantations in the Nelson region, New Zealand, a Phytophthora species was isolated in association with bleeding stem cankers and rhizosphere soil. This isolate grew more slowly than other Phytophthora species associated with P. radiata in New Zealand, and was morphologically similar to isolates of Phytophthora cactorum previously associated with horticulture production, and isolates that were morphologically identified as P. cactorum from P. radiata in Nelson since the 1970s. Phylogenetic analyses of the ITS, cox1, and ß-tubulin _F1A and ß-tubulin_F2A regions confirmed this to be a new species closely related to P. hedraiandra in Clade 1. The new species is described here as Phytophthora aleatoria sp. nov. It produces partially caducous, papillate, ovoid to rarely globose or limoniform sporangia, markedly aplerotic oogonia forming thin-walled oospores, and paragynous (mainly) or amphigynous antheridia on some cultures. To date, this species has been confirmed on P. radiata in New Zealand across a range of sites within the North Canterbury, Nelson, Hawkes Bay, Taupo and the Bay of Plenty regions.
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This work was funded by MBIE (CO4X1305), the Forest Growers Levy Trust (administered by the New Zealand Forest Owners’ Association) and the Radiata Pine Breeding Company under the “Healthy Trees, Healthy Future” research programme at Scion (NZFRI, Ltd). Strategic Science Investment Funds (MBIE, New Zealand) were also utilised for this study. Nicole Silvester, Rita Tetenburg, Sara Carey, and Tomoko Pearson are acknowledged for technical assistance. Scion’s Forest Research Culture Collection housed and maintained all the isolates used in this study.
Supplementary Fig. 1Bayesian trees produced from sequences from the ITS region (upper), β-tubulin (middle) and cox1 (lower), including species from Clade 1. Bayesian posterior probabilities are given above the branches, and maximum likelihood bootstrap values (in %) above 70% are given below the branches. Phytophthora psychrophila isolate P10433 from Clade 3 was used for an outgroup reference. (PNG 759 kb)
Supplementary Fig. 2Bayesian trees produced from concatenated sequences from the ITS region, including species from Clade 1, and additional Phytophthora aleatoria isolates sequenced from the Scion Forest Health Diagnostics Service. Bayesian posterior probabilities are given above the branches, and maximum likelihood bootstrap values (in %) above 70% are given below the branches. Phytophthora psychrophila isolate P10433 from Clade 3 was used for an outgroup reference. (PNG 771 kb)
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