Rooney-Latham Suzanne, Lutz Matthias, Blomquist Cheryl L, Romberg Megan K, Scheck Heather J, Piątek Marcin
a Plant Pest Diagnostics Center , California Department of Food and Agriculture , Sacramento , California 95832.
b Plant Evolutionary Ecology, Institute of Evolution and Ecology , University of Tübingen , Auf der Morgenstelle 5, D- 72076 Tübingen , Germany.
Mycologia. 2017 May-Jun;109(3):520-528. doi: 10.1080/00275514.2017.1362314. Epub 2017 Aug 1.
White leaf smut is a minor foliar disease of sunflower (Helianthus annuus) in the United States. The disease occurs primarily in greenhouse-grown sunflowers in California and causes leaf spot, defoliation, and a reduction in yield and crop value. Historically, many Entyloma specimens with similar morphological characters, but infecting diverse plant genera including Helianthus, were called Entyloma polysporum. Recent comparative morphological and molecular work has shown that Entyloma species infect hosts within a single genus or species, suggesting that the sunflower Entyloma species may not be E. polysporum. In 2015, sunflower leaf smut material was collected from ornamental sunflowers in a greenhouse in Santa Barbara County, California. Morphologically, this species differed from E. polysporum in having smaller, more regular-shaped teliospores and prominently developed conidiophores with cylindrical conidia. The rDNA ITS1-5.8S-ITS2 (internal transcribed spacer [ITS]) region of the sunflower leaf smut was phylogenetically distinct from all previously sequenced Entyloma species and found only on H. annuus. This study confirms that the sunflower leaf smut pathogen represents a novel species, Entyloma helianthi. Possible misidentification of the anamorphic stage of Entyloma helianthi as another leaf spot pathogen, Ramularia helianthi, is also discussed.
白叶黑粉病是美国向日葵（Helianthus annuus）的一种次要叶部病害。该病主要发生在加利福尼亚州温室种植的向日葵上，会导致叶斑、落叶，并降低产量和作物价值。历史上，许多具有相似形态特征但感染包括向日葵在内的多种植物属的叶黑粉菌标本都被称为多孢叶黑粉菌（Entyloma polysporum）。最近的比较形态学和分子研究表明，叶黑粉菌属物种感染单一属或物种内的宿主，这表明向日葵叶黑粉菌物种可能不是多孢叶黑粉菌。2015年，从加利福尼亚州圣巴巴拉县一个温室的观赏向日葵上采集了向日葵叶黑粉病材料。在形态上，该物种与多孢叶黑粉菌不同，其冬孢子更小、形状更规则，分生孢子梗显著发育，具圆柱形分生孢子。向日葵叶黑粉病的核糖体DNA ITS1-5.8S-ITS2（内转录间隔区[ITS]）区域在系统发育上与所有先前测序的叶黑粉菌属物种不同，且仅在向日葵上发现。本研究证实，向日葵叶黑粉病病原菌代表一个新物种，即向日葵叶黑粉菌（Entyloma helianthi）。还讨论了向日葵叶黑粉菌的无性阶段可能被误鉴定为另一种叶斑病原菌向日葵柱隔孢（Ramularia helianthi）的情况。
