魔芋,被称为魔芋,由于其富含葡甘露聚糖,被广泛用于生物医学和食品加工。在2019年至2022年之间,上午南部疫病严重爆发。在Mile市的主要种植区,在8月和9月观察到了muelleri。平均发病率为20%,造成约10,000平方米的15.3%的经济损失。受感染的植物显示枯萎和腐烂,在叶柄基部和块茎上都覆盖着白色密集的菌丝体和菌核垫。Am.收集覆盖有菌丝垫的muelleri叶柄基部用于病原体分离。感染的组织(n=20)用无菌水洗涤,表面用75%酒精消毒60秒,用无菌水冲洗三次,在玫瑰红琼脂(RBA)上培养,并在27℃下孵育两天(Adre等人。2022年)。将个体菌丝转移到新的RBA平板中并在27°C下孵育15天以获得纯化的培养物。随后获得了五个代表性的分离株,并表现出相同的形态特征。所有分离物都产生密集的,棉白气生菌丝体,日生长速率为1.6±0.2毫米(n=5)。10天后,所有分离物形成球形菌核(直径范围1.1至3.5毫米,.2.0±0.5mm;n=30)和不规则形状。每个板的菌核数量范围为58至113(aver=82;n=5)。这些菌核最初是白色的,随着成熟逐渐变成棕色。选择代表性分离株(17B-1)进行分子鉴定和翻译延伸因子(TEF,480NT。),内部转录间隔区(ITS,629NT。),大亚基(LSU,922NT。),和小亚基(SSU,1016NT。)用引物EF595F/EF1160R(Wendland和Koshe1997)扩增区域,ITS1/ITS4(Utama等人2022),NS1/NS4和LROR/LR5(Moncalvo等人2000),分别。ITS(GenBank登录号OP658949),LSU(OP658955),SSU(OP658952),TEF(OP679794)序列为99.19%,99.78%,99.31%,与At的99.58%相似。rolfsii分离株(分别为MT634388、MT225781、MT103059和MN106270)。因此,由分离物17B-1代表的真菌被鉴定为At。Rolfsii,证实了菌核的鉴定。,anamorph,基于文化和形态特征。对六个月大的无症状Am进行了致病性测试。muelleri植物(n=30)在温室中在27°C和80%相对湿度的无菌土壤中生长。用无菌刀片划伤叶柄基部,并通过在伤口上放置5天龄的分离物17B-1的5mm2菌丝体栓接种20株植物。在10株受伤的对照植物上使用无菌RBA塞。12天后,所有接种的植物都表现出与田间观察到的症状相似的症状,而对照植物没有症状。从接种的叶柄中重新分离出的真菌的形态和分子鉴定证实了其身份为At。Rolfsii,履行科赫的假设。S、rolfsii最早是在上午报道的。印度的campanulatus(Sarma等人。2002).如在。rolfsii在所有魔芋生长地区引起魔芋疾病(Pravi等人。2014),在的重要性。rolfsii是Am的地方性病原体。中国的muelleri需要得到认可,其患病率应确定为管理该疾病的第一步。
Amorphophallus muelleri, known as
konjac, is widely used in the biomedicine and food processing due to its richness in glucomannan. Between the years of 2019 to 2022, severe outbreaks of southern blight on Am. muelleri were observed during August and September in the main planting region of Mile city. The average disease incidence was 20%, resulted in 15.3% of economic losses in approximately 10,000 m2. Infected plants showed wilting and rotting and were covered with white dense mats of mycelia and sclerotia on both petiole base and tubers. Am. muelleri petiole base covered with mycelial mats were collected for pathogen isolation. The infected tissues (n=20) were washed with sterile water and surface disinfected with 75% alcohol for 60 seconds, rinsed three times with sterile water, cultured on rose bengal agar (RBA) and incubated at 27 ℃ for two days (Adre et al. 2022). Individual hyphae were transferred to new RBA plates and incubated at 27 ℃ for 15 days to obtain purified cultures. Five representative isolates were subsequently obtained and exhibited identical morphological characteristics. All isolates produced dense, cotton-white aerial mycelia and had a daily growth rate of 1.6 ± 0.2 mm (n=5). After 10 days, all isolates formed sclerotia in spherical (diameter range 1.1 to 3.5 mm, aver. 2.0 ± 0.5 mm; n=30) and irregular shapes. The number of sclerotia per plate ranged from 58 to 113 (aver=82; n=5). These sclerotia were initially white and gradually turned brown as they matured. A representative isolate (17B-1) was selected for molecular identification and the translation elongation factor (TEF, 480 nt.), internal transcribed spacer (ITS, 629 nt.), large subunit (LSU, 922 nt.), and small subunit (SSU, 1016 nt.) regions were amplified with the primers EF595F/EF1160R (Wendland and Kothe 1997), ITS1/ITS4 (Utama et al. 2022), NS1/NS4, and LROR/LR5 (Moncalvo et al. 2000), respectively. The ITS (GenBank accession no. OP658949), LSU (OP658955), SSU (OP658952), and TEF (OP679794) sequences were 99.19%, 99.78%, 99.31%, and 99.58% similar to those of At. rolfsii isolates (MT634388, MT225781, MT103059, and MN106270, respectively). Thus, the fungus represented by isolate 17B-1 was identified as At. rolfsii, corroborating the identification of Sclerotium rolfsii Sacc., the anamorph, based on cultural and morphological features. Pathogenicity tests were performed on six-month-old asymptomatic Am. muelleri plants (n=30) grown in pots with sterile soil in a greenhouse at 27 °C and 80% relative humidity. The petiole base was scratched with a sterile blade and 20 plants were inoculated by placing a 5 mm2 mycelial plug of five-day-old isolate 17B-1 on the wound. Sterile RBA plugs were used on 10 wounded control plants. After 12 days, all inoculated plants exhibited symptoms similar to those observed in the field, while the control plants showed no symptoms. The morphological and molecular identification of the fungus reisolated from inoculated petioles confirmed its identity as At. Rolfsii, fulfilling Koch\'s postulates. S. rolfsii was first reported on Am. campanulatus in India (Sarma et al. 2002). As At. rolfsii causes
konjac diseases in all Amorphophallus growing areas (Pravi et al. 2014), the importance of At. rolfsii as an endemic pathogen of Am. muelleri in China needs to be recognized, and its prevalence should be determined as a first step to managing this disease.