中国新宇宙孢菌引起花生荚腐病的首次报道。

First Report of Neocosmospora striata Causing Peanut Pod Rot in China.

作者信息

Sun W M, Feng L N, Guo W, Liu D Q, Yang Z H, Liu L F, Ran L X, Meng Q F

机构信息

Biological Control Center of Plant Diseases and Plant Pests of Hebei Province, College of Plant Protection, Agricultural University of Hebei, Baoding, 071000, Hebei, China.

Biological Control Center of Plant Diseases and Plant Pests of Hebei Province, College of Life Sciences, Agricultural University of Hebei and the National Engineering Research Center for Agriculture in Northern Mountainous Areas, Baoding, 071000, Hebei, China.

出版信息

Plant Dis. 2012 Jan;96(1):146. doi: 10.1094/PDIS-06-11-0461.

Abstract

In 2008, an outbreak of pod rot of peanut (Arachis hypogaea L.) occurred on most of the peanut cultivars in the Old Yellow River drainage area, the largest peanut-growing region in China. Disease incidence reached as high as 90% in some fields, causing severe yield losses. The black rot of pods and blackened, nonrotting taproots is similar to symptoms of peanut black rot caused by Cylindrocladium parasiticum, but the reddish orange perithecia of C. parasiticum were not found on the taproots close to the surface of the soil. The foliage of affected plants was generally asymptomatic, but some plants turned greener. This pod rot disease was further investigated in 2008 and 2010. Twenty-three Fusarium-like isolates were obtained from symptomatic, surface-disinfested pods with a frequency of 82%. These isolates were fast growing, with flat, thin, and grayish white colonies when cultured on potato dextrose agar (PDA) at 28°C for 3 to 4 days. The hyaline, elongated to cylindrical conidia, aggregated in slimy heads on conidiogenous cells developed from undifferentiated hyphae when observed with the light microscope. The size of conidia (single celled or one septum) varied from 3 to 9 μm long and 1.5 to 3.5 μm wide on the basis of the measurement of 50 spores. Some conidia appeared slightly curved. Ascomata formed within 10 to 14 days, with a punctate appearance on the colony. The cerebriform ascomata were dark brown, pyriform, ostiolate, glabrous, 120 to 170 × 90 to 130 μm, and with necks 30 to 50 μm long. Asci measured 60 to 90 × 6 to 10 μm, were cylindrical to cylindric-clavate, thin walled, and had an apical ring. Ascospore arrangement was obliquely uniseriate or partially biseriate, very pale yellow to hyaline, ellipsoidal, and measured 8 to 12 × 4.5 to 6 μm. Some spores had a median transverse straight or curved septum and were slightly constricted at the septum, with 6 to 10 thin, transverse, hyaline flanges. Morphological characteristics of the isolates with ascomata dark brown and ascospores with 6 to 10 transverse hyaline flanges matched the description for Neocosmospora striata (1). The internal transcribed spacer (ITS) region of rDNA was amplified from extracted template DNA with primer pairs ITS4/ITS5 and sequenced. A 591-bp amplicon (GenBank Accession No. HM461900) had 99% sequence identity with Fusarium solani (HQ607968 and HQ608009) and N. vasinfecta (GU213063), which indicated that these fungi belong to the genus Neocosmospora or Fusarium, although there is no direct sequence evidence that they are N. striata. N. striata has only been previously reported in Japan (2). This species is unique because of the dark brown ascomata and there is no comparable species (1). Koch's postulates were completed by surface-disinfesting 80 peanut pods of cv. Jihua 9813 and soaking them in conidial suspensions (10 conidia/ml) for 2 min. Another 80 other pods soaked in sterile water served as controls. All peanuts were incubated in moist petri dishes under darkness at 28°C. Symptoms similar to those originally observed in the field formed within 10 days on all inoculated peanut pods and not the controls. N. striata was reisolated from all affected peanut pods. To our knowledge, this is first report of N. striata causing peanut pod rot in China and the first description of the anamorph of the fungus. References: (1) P. F. Cannon et al. Trans. Br. Mycol. Soc. 82:673, 1984. (2) S. Udagawa et al. Trans. Mycol. Soc. Jpn. 16:340, 1975.

摘要

2008年,中国最大的花生产区——黄河故道地区的大部分花生品种爆发了花生荚腐病。部分田块发病率高达90%,造成严重减产。荚果黑腐和主根变黑但未腐烂的症状与寄生柱孢菌引起的花生黑腐病相似,但在靠近土壤表层的主根上未发现寄生柱孢菌的橙红色子囊壳。发病植株的叶片通常无症状,但有些植株会变得更绿。2008年和2010年对这种荚腐病进行了进一步调查。从有症状、表面消毒的荚果中获得了23株镰刀菌样分离物,分离频率为82%。这些分离物生长迅速,在28°C的马铃薯葡萄糖琼脂(PDA)上培养3至4天时,形成扁平、薄且灰白色的菌落。在光学显微镜下观察,透明、细长至圆柱形的分生孢子聚集在由未分化菌丝发育而来的产孢细胞的粘质头中。根据对50个孢子的测量,分生孢子(单细胞或有一个隔膜)大小为长3至9μm,宽1.5至3.5μm。一些分生孢子略显弯曲。子囊壳在10至14天内形成,菌落上呈点状。脑状子囊壳深褐色,梨形,有孔口,无毛,120至170×90至130μm,颈部30至50μm长。子囊大小为60至90×6至10μm,圆柱形至圆柱棒状,薄壁,有顶环。子囊孢子排列为斜单列或部分双列,极淡黄色至透明,椭圆形,大小为8至12×4.5至6μm。一些孢子有一条横向的直或弯曲的中隔膜,在隔膜处略有缢缩,有6至10个薄的横向透明翼。子囊壳深褐色且子囊孢子有6至10个横向透明翼的分离物的形态特征与条纹新宇宙孢菌的描述相符(1)。用引物对ITS4/ITS5从提取的模板DNA中扩增出rDNA的内部转录间隔区(ITS)并进行测序。一个591bp的扩增片段(GenBank登录号HM461900)与茄病镰刀菌(HQ607968和HQ608009)和大豆新宇宙孢菌(GU213063)有99%的序列同一性,这表明这些真菌属于新宇宙孢菌属或镰刀菌属,尽管没有直接的序列证据表明它们是条纹新宇宙孢菌。条纹新宇宙孢菌此前仅在日本有报道(2)。该物种因其深褐色的子囊壳而独特,且没有类似的物种(1)。通过对80个冀花9813品种的花生荚进行表面消毒,然后在分生孢子悬浮液(10个分生孢子/毫升)中浸泡2分钟,完成了柯赫氏法则验证。另外80个浸泡在无菌水中的荚果作为对照。所有花生在黑暗中于28°C的湿润培养皿中培养。所有接种的花生荚在10天内出现了与最初在田间观察到的相似症状,而对照则没有。从所有发病花生荚中重新分离出了条纹新宇宙孢菌。据我们所知,这是条纹新宇宙孢菌引起中国花生荚腐病的首次报道,也是该真菌无性型的首次描述。参考文献:(1)P.F. Cannon等人,《英国真菌学会会刊》82:673,1984年。(2)S.Udagawa等人,《日本真菌学会会刊》16:340,1975年。

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