Pan R, Deng Q, Xu D, Ji C, Deng M, Chen W
Department of Plant Pathology, South China Agricultural University, Guangzhou 510642, China.
Plant Protection Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China.
Plant Dis. 2012 Apr;96(4):583. doi: 10.1094/PDIS-11-11-0982.
During late July and early August of 2010, a serious disease of peanut (Arachis hypogaea L.) resembling Cylindrocladium black rot (CBR) was found in Longyan City, Fujian Province of Eastern China. Aboveground symptoms were chlorosis and yellowing of leaves, a black rot of the basal stem and pegs, and wilting of the vines. Underground plant parts (including pods, pegs, taproots, and hypocotyls) were blackened and rotted. Orange-to-reddish spherical fruiting bodies appeared on the lesions of the basal stems and pegs of peanut. Disease incidence was approximately 20%. A fungus was consistently isolated from the edge of lesions on potato dextrose agar (PDA) amended with streptomycin and incubated at 25°C. The fungus produced white-to-pale buff mycelia with a yellowish brown pigment. Optimum growth of the fungus on PDA was at 25 to 30°C. Conidiophores were borne laterally on a stipe that terminated in a hyaline, globose vesicle measuring 5.5 × 10.9 μm in diameter. Conidia were hyaline, cylindrical, rounded at both ends, slightly wider at the base than at the apex, with one to three septa (mostly one septa), and measured 27.3 to 70.9 × 4.1 to 8.2 μm. Orange-to-reddish perithecia were readily formed in old cultures. The perithecia were subglobose to oval or obovate and measured 215.6 to 609.4 × 309.4 to 496.9 μm. The asci were hyaline, clavate, thin walled, long stalked, with each containing eight ascospores. Ascospores were hyaline, falcate, had one septum, and measured 27.3 to 54.5 × 4.1 to 6.8 μm. The fungus was identified as Cylindrocladium parasiticum Crous, M.J. Wingfield, & Alfenas (teleomorph Calonectria ilicicola) (1,2). The beta-tubulin gene fragment was amplified using the T1/Bt2b primers (3) and sequenced. The sequences of three isolates (GenBank Accession Nos. JF343965, JF429656, and JF429657), when compared with existing sequences in GenBank, had 95 to 99% sequence identity with Calonectria ilicicola (GenBank Accession Nos. AY725643 and AY725639). Pathogenicity tests were conducted by first culturing the fungus on wheat kernels for 2 weeks. Inoculated kernels were then used as inoculum and mixed with sterilized soil in a proportion of 1:20 by weight in plastic pots (10 × 9 cm). Noninoculated wheat kernels were mixed with sterilized soil in the same proportion and served as the control. Two-week-old peanut seedlings (cv. Yueyou No. 7) were transplanted into inoculated or noninoculated pots. There were five plants per pot and each treatment was replicated four times. The plants were incubated in a greenhouse at 25 ± 2°C. All of the treated plants exhibited typical basal stem and root rot symptoms of CBR 2 weeks after inoculation, while all of the control plants remained healthy. C. parasiticum was reisolated from the diseased plants. To our knowledge, this is the first report of CBR on peanut in Fujian Province in Eastern China. The disease has been previously reported in Guangdong Province in Southern China but is not known elsewhere (4). This pathogen may pose a serious threat to peanut production in China, where peanut is an important crop. References: (1) D. K. Bell and E. K. Sobers. Phytopathology 56:1361, 1966. (2) P. W. Crous et al. Mycol. Res. 97:889, 1993. (3) P. W. Crous et al. Can. J. Bot. 77:1813, 1999. (4) R. Pan et al. Plant Pathol. 58:1176, 2009.
2010年7月下旬至8月初，在中国东部福建省龙岩市发现一种花生（Arachis hypogaea L.）的严重病害，症状类似柱枝双孢霉黑腐病（CBR）。地上部症状表现为叶片褪绿和黄化、基部茎和果针黑腐以及藤蔓萎蔫。地下部植株部分（包括荚果、果针、主根和下胚轴）变黑并腐烂。在花生基部茎和果针的病斑上出现橙红色至红色的球形子实体。发病率约为20%。从添加链霉素并在25°C下培养的马铃薯葡萄糖琼脂（PDA）平板上的病斑边缘持续分离到一种真菌。该真菌产生白色至浅米色菌丝体，并带有黄棕色色素。该真菌在PDA上的最适生长温度为25至30°C。分生孢子梗侧生于梗上，顶端为无色、球形的囊状体，直径5.×10.9μm。分生孢子无色、圆柱形，两端圆形，基部比顶端稍宽，有1至3个隔膜（大多为1个隔膜），大小为27.3至70.9×4.1至8.2μm。在老龄培养物中容易形成橙红色至红色的子囊壳。子囊壳近球形至椭圆形或倒卵形，大小为215.6至609.4×309.4至496.9μm。子囊无色、棒状、薄壁、柄长，每个子囊含8个子囊孢子。子囊孢子无色、镰刀形，有1个隔膜，大小为27.3至54.5×4.1至6.8μm。该真菌被鉴定为寄生柱枝双孢霉Crous、M.J. Wingfield和Alfenas（有性型为冬青柱枝双孢菌）（1,2）。使用T1/Bt2b引物（3）扩增β-微管蛋白基因片段并进行测序。与GenBank中现有序列相比，三个分离株（GenBank登录号JF343965、JF429656和JF429657）的序列与冬青柱枝双孢菌（GenBank登录号AY725643和AY725639）的序列一致性为95%至99%。致病性测试首先在麦粒上培养该真菌2周。然后将接种的麦粒用作接种物，按重量比1:20与灭菌土壤混合于塑料盆（10×9cm）中。未接种的麦粒与灭菌土壤按相同比例混合作为对照。将两周龄的花生幼苗（品种粤油7号）移栽到接种或未接种的盆中。每盆5株，每个处理重复4次。植株在25±2°C的温室中培养。接种后2周，所有处理的植株均表现出典型的柱枝双孢霉黑腐病基部茎和根腐症状，而所有对照植株保持健康。从患病植株上重新分离到寄生柱枝双孢霉。据我们所知这是中国东部福建省花生上柱枝双孢霉黑腐病的首次报道。该病害此前在中国南部广东省有报道，但其他地方未见报道（4）。这种病原菌可能对中国花生生产构成严重威胁，在中国花生是一种重要作物。参考文献：（1）D.K. Bell和E.K. Sobers。植物病理学56:1361，1966。（2）P.W. Crous等。真菌学研究97:889，1993。（3）P.W. Crous等。加拿大植物学杂志77:1813，1999。（4）R. Pan等。植物病理学58:1176，2009。
