Chen Ming, Fu Yongqi, Cheng Shanmei, Wu Fan, Li Shucheng, Xiao Liuhua, Chen Jinyin, Xiang Miaolian
Jiangxi Agricultural University, 91595, College of Agronomy, Nanchang, Jiangxi, China;
Plant Dis. 2023 Jul 16. doi: 10.1094/PDIS-02-23-0318-PDN.
Wisteria () is a well-known ornamental plant for environmental protection in the garden, which also has a high value for medicinal use. In December 2021, leaf spots were observed on plants growing on the campus of Jiangxi Agricultural University in Nanchang, Jiangxi Province (28.45° N, 115.49° E), with a incidence rate of 40% plants were infested (n = 100 investigated plants). Initially leaf spots were small and pale brown (Approx. 2 mm in diameter), which gradually expanded into round or irregular dark brown spots as disease progressed, and lesions developed greyish-white necrotic tissues in the center at later stages, eventually causing the leaves to rot. To isolate the pathogen, tissues (5 × 5 mm) at the margin of lesions were cut from ten symptomatic leaves, surface disinfected with 75% ethanol for 30 s followed by 2% sodium chloride (NaClO) for 1 min, rinsed three times with sterile distilled water, and the dried tissues were cultured on potato dextrose agar (PDA) at 28 ± 1℃ in darkness for 3 days. After culture purification, five isolates were obtained and the representative single spore isolate (ZTTJ1) was used for subsequent identification tests. After 10 days of incubation on PDA medium, colonies had dense aerial mycelium with a gray center and dark gray-green mycelium outward, with orange-red conidial masses distributed in a ring on the surface. The underside of the colonies was light gray to dark gray. Conidia were cylindrical, with ends obtuse-rounded, 11.83 to 20.74 × 3.34 to 5.33 μm (av=16.11 μm × 4.26 μm, n = 50) in size. These morphological characteristics were consistent with (Shi et al, 2019). Six conserved regions of isolate (ZTTJ1), internal transcribed spacer (), glyceraldehyde-3-phosphate dehydrogenase (), calmodulin (), β-tublin (), actin (), and chitin synthase 1 () gene regions were amplified using ITS1/ITS4 (Gardes et al, 1993), GDF/GDR (Templeton et al, 1992), CL1C/CL2C (Li et al, 2018), Bt2a/Bt2b (Prihastuti et al, 2009), ACT-512F/ACT-783R and CHS-79F/CHS-345R (Carbone et al, 1999) primers, respectively. Using BLAST, , and gene sequences (GenBank Accession No. OP703312, OP713773, OP713775, OP713776, OP713772, OP713774, respectively) were over 99% identical to (GenBank Accession No. MK967281, MH594288, MT449307, MN624110, MN107239 and MN908602, respectively). A maximum likelihood (ML) phylogenetic analysis based on sequences using MEGA7.0, placed isolate (ZTTJ1) within . To complete Koch's postulates, 10 μL spore suspension (1.0 × 106 conidia/mL) of ZTTJ1 (7-day-old culture on PDA medium) was dropped onto 10 leaves wounded with a sterilized needle and 10 non-wounded leaves, respectively. Ten wounded leaves were inoculated with sterile water as controls. All leaves were incubated at 28 ± 1 °C and 90 % relative humidity (12 h/12 h light/dark). After 7 days, all wounded leaves inoculated with developed symptoms as previously observed, while the control and non-wounded leaves remained healthy. The fungus re-isolated from the inoculated leaves were identified as by morphological and molecular identification; the pathogen causing disease in was determined to be . To our knowledge, this is the first report of causing anthracnose on in China. This work has identified the pathogenic species of the disease, which helps to take targeted measures to control its spread, providing a basis for the prevention and treatment of the disease.
紫藤()是园林中一种著名的环保观赏植物,同时也具有很高的药用价值。2021年12月,在江西省南昌市江西农业大学校园内生长的紫藤植株上观察到叶斑病,发病率为40%(共调查100株植株)。最初叶斑较小,呈浅褐色(直径约2毫米),随着病情发展逐渐扩大为圆形或不规则的深褐色斑点,后期病斑中央形成灰白色坏死组织,最终导致叶片腐烂。为分离病原菌,从10片有症状的叶片上切取病斑边缘的组织(5×5毫米),用75%乙醇表面消毒30秒,再用2%次氯酸钠(NaClO)消毒1分钟,用无菌蒸馏水冲洗3次,然后将干燥的组织在马铃薯葡萄糖琼脂(PDA)培养基上于28±1℃黑暗条件下培养3天。培养纯化后,获得5个分离株,选取代表性的单孢分离株(ZTTJ1)进行后续鉴定试验。在PDA培养基上培养10天后,菌落气生菌丝浓密,中心为灰色,向外为深灰绿色菌丝,表面有橙红色分生孢子团呈环状分布。菌落背面为浅灰色至深灰色。分生孢子圆柱形,两端钝圆,大小为11.83至20.74×3.34至5.33微米(平均值=16.11微米×4.26微米,n = 50)。这些形态特征与(Shi等人,2019年)一致。使用ITS1/ITS4(Gardes等人,1993年)、GDF/GDR(Templeton等人,1992年)、CL1C/CL2C(Li等人,2018年)、Bt2a/Bt2b(Prihastuti等人,2009年)、ACT-512F/ACT-783R和CHS-79F/CHS-345R(Carbone等人,1999年)引物分别扩增分离株(ZTTJ1)的6个保守区域,即内转录间隔区()、甘油醛-3-磷酸脱氢酶()、钙调蛋白()、β-微管蛋白()、肌动蛋白()和几丁质合酶1()基因区域。通过BLAST分析,、和基因序列(GenBank登录号分别为OP703312、OP713773、OP713775、OP713776、OP713772、OP713774)与(GenBank登录号分别为MK967281、MH594288、MT449307、MN624110、MN107239和MN908602)的序列相似度超过99%。使用MEGA7.0基于序列进行最大似然(ML)系统发育分析,将分离株(ZTTJ1)置于内。为完成柯赫氏法则验证,将ZTTJ1(在PDA培养基上培养7天)的10微升孢子悬浮液(1.0×106分生孢子/毫升)分别滴加到10片用无菌针刺伤的叶片和10片未受伤的叶片上。10片受伤叶片接种无菌水作为对照。所有叶片在28±1℃和90%相对湿度(12小时光照/12小时黑暗)条件下培养。7天后,所有接种的受伤叶片出现了之前观察到的症状,而对照和未受伤叶片保持健康。从接种叶片上重新分离出的真菌通过形态学和分子鉴定被确定为;导致紫藤炭疽病的病原菌被确定为。据我们所知,这是中国首次关于引起紫藤炭疽病的报道。这项工作确定了该病的致病物种,有助于采取针对性措施控制其传播,为该病的防治提供了依据。