小川贝母是《中国药典》中公认的“川贝母”来源。在中国,它的灯泡已被用作传统的草药咳嗽疗法约2000年。在小金和松潘进行了真菌病调查,四川省,F.unibracteata的初级栽培区,占地150英亩,2022年5月和7月。几乎所有地区都发现了锈病,所有研究地区的发病率从5%到80%不等。患病的叶子在上侧显示黄色斑点,举起buff,金色,或在下侧的粘稠蜡状脓疱。在严重的情况下,感染延伸到茎和叶柄,导致植物枯萎和死亡。精子症,aecia,和telia主要发现在叶子的下面。精孢菌散布在Aecia中,并表现出从蜂蜜黄色到栗色棕色的一系列颜色。它们的横截面直径为94.4至214.3µm,宽度为94.2至197.5µm(n=30)。它们几乎是球形的,嵌入宿主组织中,毛孔有明显的外周。Aecia是半球形的,最初是白色的,外围后来变成黄棕色,并通过中央孔打开。Aeciospores是淡黄色的,细且紧密的疣状,测量20.6至34.1×18.4至30.1µm,细胞壁厚度为1.5至2.4µm(n=51)。在植物枯萎之前,观察到细长的telia,逐渐暴露,然后最终通过表皮的纵向裂缝打开。太阳孢子是单细胞的,深棕色,长方形到椭圆形,在茎上孤独,尺寸为24.7至38.2×19.2至27.8µm(n=130),壁厚为1.6至3.1µm,先端有低透明乳头,中等皱纹,纵向平行脊。这些特征与先前对乌氏霉菌的描述一致(里斯,1917年,庄,2005).引物对LR0R(Moncalvo等人。,1995)/LR5(Vilgalys&Hester,1990)用于扩增和测序来自菌株IS909-3和IS1816的核核糖体RNA基因的大亚基(GenBankPQ008482,PQ008483)。获得的序列与RustHubb中的U.aecidiiformis菌株U1023和UBC19(KR0014142和PUN23000)具有99.9%至100%的相似性(Kaishian等人。,2024).通过形态学检查,主机范围,和序列相似性,我们确定了锈菌的种类是U.A.2023年5月,通过在室内6株健康的4岁F.unbracteata植物上喷洒孢子悬浮液(1×105孢子/mL,在0.05%Tween20溶液中)进行致病性测试。让植物在自然条件下生长,其中昼夜温度范围从9到20℃,平均气温14℃,有利于F.unbracteata的生长。用0.05%Tween20溶液喷洒另外6株幼苗作为对照。三周后,所有受感染的植物都表现出与田间相似的症状,而对照植物保持无症状。显微镜检查和测序证实,病原体形态在田间和接种之间是一致的,符合科赫的假设。尽管以前有报道说,艾氏U形会导致帕氏F.pallidiflora和ussuriensis的锈病(庄,1989年,庄,2005),这是在中国首次报道的U形藻引起的F.unbracteata生锈。这种病菌显著降低了川北木的产量和品质,强调有效识别和控制它的重要性。
Fritillaria unibracteata Hsiao et K. C. Hsia is a recognized source of \'Chuanbeimu\' in the \'Chinese Pharmacopoeia\'. In China, its bulbs have been used as a traditional herbal cough remedy for about 2,000 years. Surveys for fungal diseases were conducted in Xiaojin and Songpan, Sichuan Province, the primary cultivation region of F. unibracteata, with an area of 150 acres, in May and July 2022. Rust was found in almost all areas and incidence ranged from 5% to 80% in all study areas. Diseased leaves displayed yellow spots on the upper side, and raised buff, golden, or fuscous waxy pustules on the lower side. In severe cases, the infection extended to the stems and petioles, leading to wilting and death of plant. Spermogonia, aecia, and telia were mainly found on the underside of leaves. Spermogonia were scattered among the aecia and exhibited a range of colors from honey-yellow to chestnut-brown. They had a cross-sectional diameter of 94.4 to 214.3 µm height and 94.2 to 197.5 µm in width (n=30). They were nearly spherical, embedded in the host tissue, and had distinct periphysis at the pores. Aecia were hemispherical, initially white, with the peridium later turning yellowish-brown and opening via a central pore. Aeciospores were pale yellow, finely and closely verrucose, measuring 20.6 to 34.1 × 18.4 to 30.1 µm with a cell wall thickness of 1.5 to 2.4 µm (n=51). Prior to plants wilting, elongated telia were observed, gradually exposed, then finally opening through longitudinal cracks in the epidermis. Teliospores were unicellular, dark brown, oblong to oval, and solitary on stems, measuring 24.7 to 38.2 × 19.2 to 27.8 µm (n=130) with a wall thickness of 1.6 to 3.1 µm, with a low hyaline papilla at the apex and were moderately rugose with longitudinal parallel ridges. The characteristics align with previous descriptions of Uromyces aecidiiformi (Rees, 1917, Zhuang, 2005). The primer pair LR0R (Moncalvo et al., 1995)/LR5 (Vilgalys & Hester, 1990) was utilized for amplifying and sequencing the large subunit of the nuclear ribosomal RNA genes from strains IS909-3 and IS1816 (GenBank PQ008482, PQ008483). The obtained sequences showed a high similarity of 99.9% to 100% similarity to strains U1023 and UBC19 of U. aecidiiformis in RustHubb (KR0014142 and PUN23000)( Kaishian et al., 2024). Through examination of morphology, host range, and sequence similarity, we determined the rust species to be U. aecidiiformis. Pathogenicity testing was conducted by spraying a suspension of aeciospores (1×105 spores/mL in 0.05% Tween 20 solution) on six healthy four-year-old F. unibracteata plants indoors in May 2023. The plants were allowed to grow under natural conditions, where the diurnal temperature ranged from 9 to 20℃, with an average temperature of 14℃, which is conducive to the growth of F. unibracteata. Another six seedlings were sprayed with 0.05% Tween 20 solution as controls. After three weeks, all infected plants showed symptoms similar to those seen in the field, while control plants remained symptom-free. Microscopic examination and sequencing confirmed that the pathogen morphology was consistent between the field and the inoculation, meeting Koch\'s postulates. Although U. aecidiiformis has been previously reported to cause rust of F. pallidiflora and F. ussuriensis(Zhuang, 1989, Zhuang, 2005), this is the first report of U. aecidiiformis causing rust on F. unibracteata in China. This pathogen significantly reduces the yield and quality of Chuanbeimu, highlighting the importance of effectively identifying and controlling it.