First report of powdery mildew caused byerysiphe buhrii on Gypsophila oldhamiana in Korea

I. Y. Choi, C. H. Kang, Y. J. Song, S. E. Cho, Hyeon-Dong Shin

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Abstract

Gypsophila oldhamiana L., from family Caryophyllaceae, is native to China and Korea. Its roots have been used as a substitute in traditional Chinese medicine for Yin-Chai-Hu (roots of Stellaria dichotoma) (Luo et al. 2008). Due to its ability to survive as a dominant plant species in serpentine soil having high nickel, chromium, and cobalt contents, G. oldhamiana is of ecological significance (Kim et al. 1997). In October 2015, about 100 plants of G. oldhamiana were found affected by a powdery mildew at a disease incidence of 100% in an experimental plot in Iksan (35°56′38.47″ N; 126°59′37.04″ E), Korea. Powdery mildew colonies first appeared as thin patches on both sides of the leaves. As the disease progressed, the plants were covered with abundant masses of the mycelia and conidia, resulting in premature senescence and decreased aesthetic and medicinal value. A specimen was deposited in the Korea University Herbarium (KUS-F29015). Hyphal appressoria were well-developed, multilobed or moderately lobed, single or opposite in pairs. Conidiophores were straight, 95 to 140 × 7.0 to 9.5 µm. Foot-cells of conidiophores were cylindrical or slightly sinuous at the base, and 33 to 50 µm long, followed by 2 to 3 cells. Singly produced conidia were cylindrical to oblong-elliptical, 35 to 53 × 12 to 17 µm with a length/width ratio of 2.1 to 3.8, showed angular/rectangular wrinkling of outer walls, and devoid of distinct fibrosin bodies. Germ tubes were produced in the perihilar position of conidia. No chasmothecia were found during the growing season. These structures are typical of the powdery mildew Pseudoidium anamorph of the genus Erysiphe. The morphological characteristics and host range were consistent with those of E. buhrii U. Braun (Braun and Cook 2012). To confirm the identification, the internal transcribed spacer (ITS) regions of isolate KUS-F29015 were amplified with primers ITS5 and P3 as described by Takamatsu et al. (2009), and sequenced directly. The resulting 758 bp sequence was deposited in GenBank (Accession No. KU945278). A GenBank BLAST search of the Korean isolate showed >99% similarity with E. buhrii on G. paniculata from Korea (KJ530705) and Japan (LC009959). Pathogenicity was confirmed through inoculation by gently dusting conidia onto leaves of five healthy, potted G. oldhamiana. Five noninoculated plants served as controls. Plants were maintained in a greenhouse at 24 to 30°C. Inoculated plants developed signs and symptoms after 7 days, whereas the control plants remained symptomless. The fungus present on the inoculated plants was identical morphologically to that originally observed on diseased plants. Powdery mildew of Gypsophila spp. caused by E. buhrii has been recorded in several European countries, Mongolia, Korea, and Argentina (Farr and Rossman 2016). To our knowledge, this is the first report of powdery mildew caused by E. buhrii on G. oldhamiana globally as well as in Korea. This information would be helpful for Gypsophila producers, breeders, and gardeners.

Original languageEnglish
Pages (from-to)2164
Number of pages1
JournalPlant Disease
Volume100
Issue number10
DOIs
Publication statusPublished - 2016 Oct 1

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ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Plant Science

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