First report of stem rot on hydrangea caused by Phytophthora hedraiandra in Japan
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First report of stem rot on hydrangea caused by Phytophthora hedraiandra in Japan Rani Yosilia1,3,5 · Masaji Morishima2 · Ayaka Hieno3 · Haruhisa Suga4 · Koji Kageyama3 Received: 2 March 2020 / Accepted: 7 April 2020 © The Phytopathological Society of Japan and Springer Japan KK, part of Springer Nature 2020
Abstract A stem rot disease appeared on hydrangea plants in Tochigi Prefecture, Japan. Four Phytophthora-like isolates were obtained, and a representative isolate was selected for analysis. Hydrangea plants inoculated with the isolate developed similar symptoms. Molecular phylogenetic analyses using the rDNA ITS region and cox1, EF1-α, and β-tubulin genes indicated that the isolate was Phytophthora hedraiandra. The sporangia were papillate, laterally sessile, and caducous. Antheridia were paragynous or amphygynous, and laterally sessile, and the oospores were aplerotic. Based on these characteristics, the isolate was identified as P. hedraiandra. We suggest naming this hydrangea disease “Ajisai kukieki byo”. Keywords Ajisai · Hydrangea macrophylla · New disease · Phytophthora hedraiandra · Phytophthora stem-rot Hydrangea (Hydrangea macrophylla; Hydrangeaceae), or Ajisai in Japanese, is native to Japan and typically flowers during the rainy season. Hydrangea is grown commercially, which has led to the development of new diseases that can spread rapidly between plants, especially in intensive agricultural systems. In March 2013, in a hydrangea greenhouse in Tochigi Prefecture, a stem rot disease was found on the basal parts of hydrangea plants of cvs. Furaumiyuki and Furauaya. The rot extended to the roots in severe cases. The plants gradually wilted, and their leaves became chlorotic (Fig. 1a). The stem base gradually changed from light green The nucleotide sequence data reported are available in the GenBank database under accession numbers MG786590, MN547316, MN547317, MN547315. * Koji Kageyama [email protected]‑u.ac.jp 1
Graduate School of Applied Biological Sciences, Gifu University, Gifu 501‑1193, Japan
2
Tochigi Prefectural Agricultural Experiment Station, Tochigi 320‑0002, Japan
3
River Basin Research Center, Gifu University, Gifu 501‑1193, Japan
4
Life Science Research Center, Gifu University, Gifu 501‑1193, Japan
5
Present Address: Integrated Laboratory for Innovation and Technology, University of Lampung, Bandar Lampung 35145, Indonesia
to dark brown and eventually dried (Fig. 1b). Around 10% of plants were affected by the disease, resulting in extensive damage and large economic losses. To isolate the disease-causing agent, we placed infected stems from one plant of each cultivar on NARM agar containing nystatin, ampicillin, rifampicin, and miconazole (Morita and Tojo 2007). Oomycetes that grew on the medium were plated on corn meal agar, and four similarlooking isolates were obtained. One representative isolate was then grown on V8 juice agar at 25 °C in the dark for 6 days and used to inoculate plants of cv. Fujinotaki. One stem of two healthy two-stemmed plants w
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