First Report of Rhizopus arrhizus (syn. R. oryzae) Causing Garlic Bulb Soft Rot in Hebei Province, China
First Report of Rhizopus arrhizus (syn. R. oryzae) Causing Garlic Bulb Soft Rot in Hebei Province, China
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中国河北省首次报道无根根霉（R. oryzae）引起大蒜球茎软腐病
DOI：
10.1094/pdis-05-22-1024-pdn
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发表时间：
2022
期刊：
影响因子：
4.5
通讯作者：
Miao Gao
中科院分区：
文献类型：
--
作者：
Ya-Nan Zhang;Zhong Ji Wang;Bryan Swingle;Bang Yan Niu;Jing Xu;Xing Ma;Hailei Wei;Miao Gao
根霉软腐病发生在世界各地的蔬菜、水果和观赏植物的肉质组织上（Cui et al. 2019）。2021年11月，当大蒜在田间处于苗期时（图S1），中国河北省邯郸市大名县（N 36° 17 '，E 115° 13'）发生疑似根霉软腐病的大蒜鳞茎病害暴发。该病害症状在国内首次发现于大蒜苗期。栽培大蒜种球发病率为10%~ 30%。病蒜鳞茎表面有柔软的水浸病斑，内部呈褐色，柔软。在发病严重的田间，在发病的大蒜鳞茎上观察到白色至灰色的菌丝体。对受感染的大蒜鳞茎进行取样，以分离和确定致病生物体的身份。将Symptoms球用1%NaClO表面灭菌2分钟，浸入75%乙醇中3分钟，并用高压灭菌的蒸馏水冲洗三次。取出内部腐烂组织的小块，并在28°C下在马铃薯葡萄糖琼脂（PDA）上培养2至3天。5个白色菌落在PDA上生长，然后变为棕灰色至黑灰色菌丝体。采用菌丝尖分离法对菌株进行纯化。为了确定五种分离的真菌的身份，我们分析了它们的内部转录间隔区（ITS）序列（Jung et al. 2012）。对来自DSF-0-2（登录号ON706022）、DSF-0-3（登录号ON706021）、DSF-0-4（登录号ON706020）、DSF-0-5（登录号ON706019）和DSF-0-6（登录号ON706018）的ITS序列的BLAST分析均与少根根霉（Rhizopus arrhizus）（syn.根霉属Rhizopus sp.）基于ITS rRNA基因序列，使用MEGA 11的邻接法构建系统发育树（Walther et al. 2013）。系统发育树分析表明，这些菌株很可能是少根根霉Rhizopus arrhizus（syn.根霉属（Rhizopus）（图S2）。我们选择了一株分离菌株DSF-0-2进行形态特征分析并测试其引起大蒜鳞茎软腐病的能力。在显微镜下观察到无隔假根、孢子囊和孢子囊孢子，
Rhizopus soft rot occurs on the succulent tissues of vegetables, fruits, and ornamental plants throughout the world (Cui et al. 2019). When the garlic is in the seedling stage in the fields (Fig. S1) in November 2021, a disease outbreak on garlic bulbs suspected as Rhizopus soft rot occurred in Daming County, Handan City, Hebei Province of China (N 36°17', E 115° 13'). This disease symptom was first found in the garlic seedling stage in China. Disease incidence was 10% to 30% in cultivated garlic bulbs. There were soft water-soaked lesions on the surface of diseased garlic bulbs and the interiors were brown and soft. In the disease severe field, white to gray mycelia were observed on the diseased garlic bulbs. Infected garlic bulbs were sampled to isolate and determine the identity of the disease-causing organism. Symptomatic bulbs were surface sterilized with 1% NaClO for 2 min, dipped in 75% ethanol for 3 min and rinsed three times with autoclaved distilled water. Small pieces of the inner decayed tissue were removed and cultured on potato dextrose agar (PDA) at 28°C for 2 to 3 days. Five white colonies grew on PDA and then they became brownish gray to blackish-gray mycelium. The fungal strains were purified by hyphal-tip isolation method. To determine the identity of the five isolated fungi, we analyzed their internal transcribed spacer (ITS) region sequences (Jung et al. 2012). BLAST analysis of the ITS sequences from DSF-0-2 (accession no. ON706022), DSF-0-3 (accession no. ON706021), DSF-0-4 (accession no. ON706020), DSF-0-5 (accession no. ON706019) and DSF-0-6 (accession no. ON706018) were all 100% identical with Rhizopus arrhizus (syn. Rhizopus oryzae). Phylogenetic trees were constructed using the neighbor-joining method of MEGA11 based on the sequences of ITS rRNA gene (Walther et al. 2013). Phylogenetic trees indicated that isolates were most likely Rhizopus arrhizus (syn. Rhizopus oryzae) (Fig. S2). We selected one isolated strain, DSF-0-2, for characterize the morphology and test its ability to cause garlic bulb soft rot. Under the microscope, nonseptate rhizoids, sporangia, and sporangiospores were