CSIRO PUBLISHING www.publish.csiro.au/journals/apdn Australasian Plant Disease Notes, 2009, 4,21–22

S-type on lilac in Australia

J. H. Cunnington A,B and R. W. Brett A

ABiosciences Research Division, Department of Primary Industries, Knoxfield, Private Bag 15, Ferntree Gully Delivery Centre, Victoria 3156, Australia. BCorresponding author. Email: [email protected]

Abstract. In 2004, powdery mildew on lilac () was collected in a home garden in an inner suburb of Melbourne. At that time it could not be identified, but appeared to be the only verifiable record of powdery mildew on lilac in Australia. A recombinant DNA internal transcribed spacer sequence from a 2008 sample, collected from the same garden, revealed that the is the S-type lilac powdery mildew that lacks a clear name.

Powdery mildew occurs on lilac (Syringa spp.) in many parts of the world. Braun (1987) recognised two species of powdery mildew fungi; syringae Schwein. ( Microsphaera syringae (Schwein.) H. Magn.) and E. syringae-japonicae U. Braun & S. Takam. ( Microsphaera syringae-japonicae U. Braun). The former occurs in Europe and North America. The latter occurs in Asia. The main morphological difference between the two species is that E. syringae forms four or fives ascospores per ascus, while E. syringae-japonica forms 6–8 spores per ascus. However, Bolay (2005) could not find this difference in ascospore numbers and concluded that they were both the same species. A molecular phylogenetic study was undertaken by Seko et al. (2008) to clarify the status of the two species. Seko et al. (2008) demonstrated that two species were present, but could not assign names to them, instead calling them K-type and S-type. Interestingly, the S-type appeared to have been present for a long time in Europe and North America, while the K-type originated in Asia. The K-type then spread to Europe in the early 1990s and out-competed the S-type to become the dominant species. In December 2004, powdery mildew on lilac (Syringa vulgaris) was collected in a home garden in an inner Melbourne suburb. The shrub was very heavily infected (Fig. 1). Microscopic examination of the fungus revealed that it was a typical Pseudoidium-type anamorphic powdery mildew. Basic morphological characters agreed with those of both E. syringae and E. syringae-japonica (Braun 1987). Conidia were formed singly, ovoid-to-ellipsoid, ~25–30 Â 10–15 mm, without fibrosin bodies. Appressoria were multilobed. At that time no further identification was possible. Material was collected from the same garden in April 2008. Fig. 1. Powdery mildew on lilac (VPRI 41368). On this occasion it was decided to obtain a ribosomal DNA internal transcribed spacer (rDNA ITS) sequence to compare with the sequences of the S-type and K-type lilac powdery Total DNA was extracted from leaf material of specimen mildews published by Seko et al. (2008). Both specimens VPRI 41368 using a DNeasy Plant Mini Kit (Qiagen, have been deposited in the Department of Primary Industries Melbourne, Australia). The rDNA ITS region was amplified Victoria Plant Pathology Herbarium (VPRI 32130 and 41368). using primers PMITS1 and PMITS2 (Cunnington et al. 2003).

Australasian Plant Pathology Society 2009 10.1071/DN09009 1833-928X/09/010021 22 Australasian Plant Disease Notes J. H. Cunnington and R. W. Brett

The polymerase chain reaction products were sequenced directly References using primers ITS5 and ITS4 (White et al. 1990). A similarity Amano K (Hirata) (1986) Host Range and Geographical Distribution of the search of GenBank sequences revealed the sequence to be Powdery Mildew Fungi. 741 pp. (Science Society Press: Tokyo, Japan) identical to AB295460 (Seko et al. 2008) the S-type lilac Bolay A (2005) Les oïdiums de Suisse (Erysiphaceae). Cryptogamica powdery mildew. The sequence obtained here has been Helvetica 20,1–173. deposited in GenBank as accession FJ755790. Braun U (1987) A monograph of the (powdery mildews). Beiheft Powdery mildew on lilac in Australia has been recorded under zur Nova Hedwigia 89,1–700. the name Microsphaera alni (Chambers 1982), but this reference Chambers SC (1982) Lists of diseases recorded on ornamentals, native plants does not provide any details on its occurrence, stating only that and weeds in Victoria, before 30 June, 1980. (Department of Agriculture, it is a ‘pre-1940’ report. No specimens of powdery mildew on Government of Victoria, Technical Report Series No. 61. 104 pages) lilac could be found in any Australian plant pathology herbaria, Cook RP, Dubé AJ (1989) Host-pathogen index of plant diseases in South Australia. (South Australian Department of Agriculture: Adelaide) and the disease is not listed in any other state agriculture Cunnington JH, Takamatsu S, Lawrie AC, Pascoe IG (2003) Molecular department checklists (Simmonds 1966; Sampson and Walker identification of anamorphic powdery mildew fungi. Australasian 1982; Cook and Dubé 1989; Shivas 1989). Braun (1987) lists Plant Pathology 32, 421–428. doi: 10.1071/AP03045 E. syringae in Australia, but this is based on Amano (1986) Harrison DE, Wimalajeewa DLS, Chambers SC (1975) List of diseases (U. Braun, 2008 pers. comm.) which was written from an recorded on vegetables in Victoria before June 30, 1974. (Department extensive worldwide literature review. The source of this of Agriculture, Victoria, Technical Bulletin No. 25: Melbourne) record is unclear as Amano (1986) does not reference Sampson PJ, Walker J (1982) An annotated list of plant diseases in Tasmania. Chambers (1982). But Amano (1986) does cite a personal (Department of Agriculture, Tasmania: Hobart) communication from T.H. Harrison in 1961 on powdery Seko Y, Bolay A, Kiss L, Heluta V, Grigaliunaite B, Takamatsu S (2008) mildews in Australia, although this is not directly linked to the Molecular evidence is support of recent migration of a powdery mildew fungus on Syringa spp. into Europe from East Asia. Plant Pathology powdery mildew on lilac. Amano (1986) also references 57, 243–250. doi: 10.1111/j.1365-3059.2007.01775.x Harrison et al. (1975) but this publication does not mention Shivas RG (1989) Fungaland bacterialdiseasesof plantsin WesternAustralia. diseases of lilac. Journal of the Royal Society of Western Australia 72,1–62. We do not know if this is a new introduction into Australia Simmonds JH (1966) Host index of plant diseases in Queensland. given the rarity of the fungus. Given that the pre-1940 report (Queensland Department of Primary Industries: Brisbane) (Chambers 1982) cannot be confirmed, it is likely that we will White TJ, Bruns TD, Lee S, Taylor JW (1990) Amplification and direct never know. Since lilac is commonly grown in Australia and sequencing of fungal ribosomal RNA genes for phylogenetics. In ‘PCR the powdery mildew symptoms are so striking, it seems Protocols: a guide to methods and applications’. (Eds MA Innis, – unlikely that lilac powdery mildew would have remained DH Gelfand, JJ Sninsky, TJ White) pp. 315 322. (Academic Press: undetected since the 1940s. If it is a recent arrival, it is London) interesting that it is the old European S-type, not the more aggressive Asian K-type. Manuscript received 2 December 2008, accepted 28 February 2009

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