Sclerotinia nivalis, sp. nov., the pathogen of snow mold of herbaceous dicots in northern Japan

Abstract

A new Sc/erotinia, previously reported as S. intermedia from Japan, is described as Sclerotinia nivalis on the morphological basis of the sclerotial anamorph and teleomorph produced in culture. The characters assigning this species to the genus Sclerotinia are the tuberoid sclerotia superficially produced on suscepts, the small sclerotia produced on aerial mycelium in culture, the interhyphal spaces in medullary tissue of sclerotia, and the globose cells constructing the ectal excipulum of apothecia. It is distinguishable from S. sclerotiorum, S. minor, and S. trifoliorum by the intermediate sized sclerotia in culture, binucleate ascospores, the molecular mass of major proteins of sclerotia, and the patterns of esterase isozymes in sclerotial extracts. Although S. nivalis causes snow mold of various dicots, it is a mesophile having an optimum temperature for mycelial growth of around 20~It attacks edible burdock (Arctium lappa), Chryhsanthemum morifolium, Ambrosia elatior, carrot (Daucus carota), Angelica acutiloba, Ajuga reptans, and Plantago lanceolata.Key Words herbaceous dicots; mesophilic fungus; Sclerotinia; snow mold.Tochinai and Sugimoto (1958) studied a snow-mold disease of santonica (Artemisia maritima L., the source plant for santonin industry) caused by a sclerotiniaceous fungus, which had been the major problem for santonica cultivation in Hokkaido since the early 1940s. They identified the causal organism with Sclerotinia intermedia Ramsey, which was synonymized with Sclerotinia sclerotiorum (Lib.) de Bary by Purdy (1955) proposing a broader concept of the species S. sclerotiorum based on variability of morphological characters that had been used for identification. The characters of the organism that Tochinai and Sugimoto adopted in their identification are the color of mycelium on the suscept (not always white), temperature response in mycelial growth (faster growth at 0~ than S. sclerotiorum and S. trifoliorum Erikss.), intermediate size of sclerotia produced at 25 ~ (1.9-4.3mm) and measurements of asci (118.5x 7.3/~m) and ascospores (10.5x4.5~m).Later, autumn-sown rape (Brassica campestris L. subsp, napus Hook.) and summer-sown carrot (Daucus carota L.) left unharvested in the field were found to be damaged by the same organism under the similar conditions as with santonica (Sugimoto et al., 1962;Narita, 1980). Although there have been no published records, the organism found by Tochinai and Sugimoto was also considered to cause snow-mold disease of pyrethrum (Chrysanthemum cinerariaefolium Bocc.), the source plant for pyrethrin industry, which was widely cultivated in Hokkaido in the 1930s (Narita, 1980). Thereafter, the organism has become rare in agricultural sites in Hokkaido because of the decline of cultivation of perennial or biennial dicot crops which could be suscepts. On the other hand, the recent taxonomic revision of Sclerotiniaceae (Kohn, 1979) that synonymized S. intermedia with Sclerotinia minor Jagger led to the re-examination of the organism designated as S. intermedia in Japan,...

Ciborinia gentianae sp. nov., the causal organism of sclerotial flower blight of cut-flower gentians

“…The traditional characters for identification of Ciborinia species are host, morphology of apothecia (size, presence or absence of rhizoidal tuft in stipe base), measurements of asci and ascospores (Seaver 1951;Groves and Bowerman 1955;Batra 1960;Huhtinen 1985;Palmer 1992), and number of ascospores in asci (Zhuang and Wang 1997). In addition, the nuclear number of ascospores appears to be a valid character to identify a species in the Sclerotiniaceae (Kohn 1979a;Saito 1997), and we revealed tetranucleate ascospores of C. gentianae in this study; however, the published descriptions on ciborinias lack comparable nuclear data except for C. camelliae (Kohn and Nagasawa 1984) and C. ciborium (Schumacher and Kohn 1985). With apothecial size, C. gentianae differs from species having minute apothecia (1-2 mm diameter) (C. Groves and Bowerman (1955); C, Batra and Korf (1959); D, Batra (1960); E, Kohn (1982); F, Kohn and Nagasawa (1984); G, Huhtinen (1985); H, Lew and Wu (1985); I, Schumacher and Kohn (1985); J, Palmer (1992); K, Tamura et al (1996); L, Zhuang and Wang (1997) (Seaver) Seaver; C. camelliae (Hara) L.M.…”

Environments influence the psychrophily of fungi and oomycetes in the cryosphere

“…However, when cultures were covered with unsterile soil to introduce natural microbial antagonists, mycelial growth was much less at 10°C than at 0°C (Matsumoto & Tajimi 1988, Hsiang et al 1999. These facts indicate that T. ishikariensis group I is unable to develop mycelia at 10°C in nature The ascomycetous snow mould, Sclerotinia nivalis is psychrotolerant and its optimal mycelial growth temperature is 20°C (Saito 1997). However, the fungus could infect santonica (Artemisia cina) and carrot at 0 or 3°C but not at 15°C (Saito 2001).…”

Sclerotinia trillii, sp. nov., causing a new sclerotinia disease on Trillium in Japan

“…Proteins were extracted based on the procedures of Scott (1981) and Saito (1997). 2.5-2.6 g of sclerotia were ground in mortars with quartz sand and 5 ml of 0.05 M Tris-HCI-buffer (pH 6.8) on crushed ice.…”