Badillo-Ponce G, Fernández-Pavía S P, Grünwald N J, Garay-Serrano E, Rodríguez-Alvarado G, Lozoya-Saldaña H
ICAMEX, Conjunto SEDAGRO Metepec, Mexico, 52140.
Instituto de Investigaciones Agropecuarias y Forestales, Universidad Michoacana de San Nicolás de Hidalgo, Tarímbaro, Mexico, 58880.
Plant Dis. 2004 Nov;88(11):1283. doi: 10.1094/PDIS.2004.88.11.1283C.
Several wild species of Ipomoea grow in the central highlands of Mexico. During the summer of 1999, in Metepec, Mexico, blighted leaves and petioles of Ipomoea purpurea were collected from diseased plants and placed in a moist chamber to induce sporulation. Sporangia that formed on the lesions were transferred with a piece of agar to selective rye agar medium (2). Phytophthora ipomoeae was consistently isolated. Species identification was based on sporangial and gametangial characteristics of five cultures grown on rye agar. Sporangia were mainly ellipsoid but occasionally ovoid, semipapillated, and deciduous with a short pedicel. All isolates were homothallic with smooth-walled and aplerotic oospores. Genotypic analysis for the allozymes Peptidase (Pep) and Glucose-6-phosphate isomerase (Gpi) indicated that all five isolates belonged to one genotype with alleles 78/78 (Pep) and 108/108 (Gpi). Morphological characteristics and the allozyme genotype correspond to the new, recently described species P. ipomoeae Flier & Grünwald (1) isolated from I. orizabensis (Pelletan) Ledeb. ex Steud. (I. tyrianthina) Lindl. and I. longepedunculata (Mart. & Gal.) Hemsl. Pathogenicity tests were carried out with leaves from greenhouse-grown I. purpurea plants. Detached leaves were inoculated with a suspension of 10 sporangia per ml and kept in a moist chamber at room temperature (17 ± 3°C). Lesions were observed between 7 and 15 days after inoculation and were characteristic of those observed in the field. The pathogen was reisolated from inoculated symptomatic tissue. To our knowledge, this is the first report of blight on I. purpurea caused by P. ipomoeae. References: (1) W. Flier et al. Mycol. Res. 106:848, 2002. (2) N. J. Grünwald et al. Phytopathology 91:882, 2001.
几种野生的甘薯属植物生长在墨西哥中部高地。1999年夏天，在墨西哥的梅特佩克，从患病植株上采集了染病的紫牵牛叶片和叶柄，并置于潮湿的培养箱中以诱导孢子形成。在病斑上形成的孢子囊用一块琼脂转移到选择性黑麦琼脂培养基上（2）。始终能分离出甘薯疫霉。物种鉴定基于在黑麦琼脂上培养的五种培养物的孢子囊和配子囊特征。孢子囊主要为椭圆形，但偶尔为卵形，半乳头状，具短柄且易脱落。所有分离株都是同宗配合的，卵孢子壁光滑且无孔。对同工酶肽酶（Pep）和葡萄糖-6-磷酸异构酶（Gpi）的基因型分析表明，所有五个分离株都属于一个基因型，其等位基因为78/78（Pep）和108/108（Gpi）。形态特征和同工酶基因型与最近描述的从稻叶牵牛（Pelletan）Ledeb. ex Steud.（tyrianthina牵牛）Lindl.和长柄牵牛（Mart. & Gal.）Hemsl.分离出的新物种甘薯疫霉Flier & Grünwald（1）相符。用温室种植的紫牵牛植株的叶片进行致病性测试。将离体叶片接种每毫升含10个孢子囊的悬浮液，并置于室温（17±3°C）的潮湿培养箱中。接种后7至15天观察到病斑，其特征与在田间观察到的一致。从接种的有症状组织中重新分离出病原体。据我们所知，这是关于甘薯疫霉引起紫牵牛疫病的首次报道。参考文献：（1）W. Flier等人，《真菌学研究》106:848，2002年。（2）N. J. Grünwald等人，《植物病理学》91:882，2001年。
