百香果(Passiloraedulis),被誉为“果汁之王”,在中国南方很受欢迎(Yuan等人。2019)。茎基部腐烂是百香果的破坏性疾病,通常由几种镰刀菌引起。(扎卡里亚,2022年)。2022年7月,在管理不善的“秦米号”中观察到了茎基部腐烂的典型症状。9“靖西金百香果园(北纬23°13\'10\”,106°5\'23\“E)。在调查中,该疾病的发病率达到40%(n=200)。症状包括茎基部溃疡和肢解,使植物在拉动时容易破损,地面上枯萎和下垂的叶子,严重的病例导致整个植物枯萎和死亡。收集有明显症状的植物14株。从疾病和健康的茎的交界处切下植物组织的薄片,用乙醇和次氯酸钠灭菌,并置于28℃的PDA培养基上。获得了60株真菌,其中90%根据形态学鉴定为镰刀菌。80%的镰刀菌是尖孢镰刀菌物种复合体(FOSC),但致病性实验显示所有FOSC均为弱致病性。然而,从同一植物中鉴定出两种形态相似但与镰刀菌不同的严重致病真菌。选择代表性菌株C11用于进一步研究。C11显示出快速增长的速度,在25°C培养7天的PDA上达到90mm直径的菌落。殖民地流离失所了一圈,扁平形状,整体浅棕色,和棉灰色或浅棕色菌丝体,而背面是深棕色。在OA培养基上培养14天后,观察到分生孢子产生通常发生在多条链中,圆的,椭圆形或直的棒状棕色分生孢子,大小为5.74-23.42×14.67-67.22,具有1-8个横向间隔和0-3个纵隔(图S1)。对于分子鉴定,内部转录间隔区(ITS,OR616614),平移延伸因子1-α(TEF,OR633298),交链孢菌主要过敏原(Alta1,OR633294)基因,甘油醛3-磷酸脱氢酶(GAPDH,OR633295),RNA聚合酶亚基II基因(RPB2,OR633297),18S小亚基rDNA(SSU,OR616608),28S大亚单位rDNA(LSU,OR616615),从C11扩增KOG1058基因区域(OR633296)和匿名非编码区的近似片段(OPA10-2,OR633299)(Liu等人。1999年,李等人。2023年,安德鲁等人。2009),并存入GenBank,括号内显示登录号。在通过BioEdit剪接后在MEGA11中构建系统发育树(图S3)。结合形态学和分子分析,C11被鉴定为链格孢菌(Woudenberg等人。2015).为了测试致病性,50健康的“泰农号”的幼苗茎的基部(高度为20cm)。1“各种紫色百香果,更容易受到茎基部腐烂的影响,用针头刺穿伤口,接种6毫米直径的真菌菌落,然后用湿棉包裹(Angel等人。2018)。用10株接种PDA的健康幼苗作为对照。这些植物在30±5℃、80±5%湿度的人工温室中培养。15天后,接种C11的植物表现出与田间相似的症状,而对照组保持健康。A.gossypina从患病的植物茎中重新分离,形态和GAPDH序列与接种一致(图S1,S2)。这是A.gossypina引起的百香果茎腐烂的第一份报告。这一发现将有助于预防和控制百香果中的茎腐病。
Passion fruit (Passilora edulis), known as the \"king of fruit juices\", is popular in southern China (Yuan et al. 2019). Stem base rot is a devastating disease of passion fruit commonly caused by several Fusarium spp. (Zakaria, 2022). In July 2022, typical symptoms of stem base rot were observed in a poorly managed \"Qinmi No. 9\" Golden passion fruit orchard in Jingxi (23°13\'10\"N, 106°5\'23\"E). The disease incidence had reached 40% (n=200) in the survey. Symptoms included ulceration and mutilation at the stem base, making the plants prone to breakage when pulled, wilting and drooping leaves above ground, and severe cases leading to the entire plant withering and dying. Fourteen plants with obvious symptoms were collected. Thin sections of plant tissue were cut from junction of sickness and health of stem, sterilized with ethanol and sodium hypochlorite, and placed on PDA medium at 28°C. Sixty fungal strains were obtained, 90% of which was identified as Fusarium based on morphology. 80% of Fusarium were F. oxysporum species complex (FOSC), but pathogenicity experiment showed all FOSC were weakly pathogenic. However, two severely pathogenic fungi with similar morphology but distinct from Fusarium were identified from the same plant. The representative strain C11 was selected for further study. C11 demonstrated a rapid growth rate, reaching a 90 mm diameter colony on PDA cultured at 25°C for 7 days. The colony displaced a round, flat shape with an overall light brown front, and cottony gray or light brown mycelium, while the reverse side was dark brown. Conidia production was observed as typically occurred in multiple chains after 14 days culture on OA medium, with round, oval or straight rod-like brown conidia ranging in size from 5.74-23.42×14.67-67.22, featuring 1-8 transverse septa and 0-3 mediastinum (Figure S1). For molecular identification, the internal transcribed spacer (ITS, OR616614), translation elongation factor 1-alpha (TEF, OR633298), alternaria major allergen (Alt a1, OR633294) gene, glyceraldehyde 3-phosphate dehydrogenase (GAPDH, OR633295), RNA polymerase subunit II gene (RPB2, OR633297), 18S Small subunit rDNA (SSU, OR616608) , 28S Large Subunit rDNA (LSU, OR616615), the KOG1058 gene regions (OR633296) and an approximately segment of the anonymous noncoding region (OPA10-2, OR633299) were amplified from C11 (Liu et al. 1999, Li et al. 2023, Andrew et al. 2009), and deposited in GenBank with accession number shown in the brackets. Phylogenetic trees were constructed in MEGA11 after splicing by BioEdit (Figure S3). Combining morphology and molecular analyses, C11 was identified as Alternaria gossypina (Woudenberg et al. 2015). To test the pathogenicity, the base of the seedling stem (20cm in height) of 50 healthy \"Tainong No. 1\" variety of purple passion fruit, which was more susceptible to stem-base rot, was puncture wound with needles, inoculated with 6 mm diameter colonies of fungi, and then wrapped in wet cotton (Ángel et al. 2018). Ten healthy seedlings inoculated with PDA were used as controls. These plants were cultured in an artificial greenhouse at 30±5℃with 80±5% humidity. After 15 days, the plants inoculated with C11 exhibited symptoms similar to those in the field, whereas the controls remained healthy. A. gossypina was reisolated from the diseased plant stems, with the morphology and GAPDH sequence consistent with the inoculated (Figure S1, S2). This is the first report of passion fruit stem rot caused by A. gossypina. This finding will aid in the prevention and control of stem rot in passion fruit.