ABSTRACT

Production of guttation droplets in the cultures of Colletotrichum falcatum was often noticed. Hence, formation of guttation droplets, exudation of toxin in guttation, and guttation droplet chemical composition were assessed to find the ecological importance of guttation. Among the tested culture media, more guttation was noticed in oat meal agar medium and host extracts broth medium. Assessing the effect of five different carbon sources on guttation of C. falcatum showed that among solid media, sparse guttation droplets were noticed in glucose-, fructose-, and starch-amended media, whereas in broth cultures except fructose-amended media no other carbon sources induced guttation in mycelium. The guttation phenomenon was noticed only in sporulating mycelia, and it also followed a specific pattern in connection with sporulation. Bioassay of guttation exudates on sugarcane leaves produced pronounced necrotic lesions with large, yellow halo similar to positive control, thus confirming the presence of toxin. The guttation fluid initiated browning symptom on sugarcane leaves at a concentration of 1000 ppm and produced pronounced necrotic lesions of 3.7 cm at 10 000 ppm. The toxicity of crude fraction was thermostable up to 60 C. The gas chromatography–mass spectrometry (GC-MS) analysis of crude guttation droplets identified the presence of 24 compounds belonging to fatty acids, derivatives of fatty acids, flavonoids, flavonoid glycosides, sterols, quinone derivatives, amides, and glycol ethers, and among them fatty acids were dominant. The two compounds, viz., hexadecanoic acid methyl ester and 9-octadecenoic acid (Z) methyl ester, were abundant (18.14% and 17.98%, respectively) and identified as probable toxic compounds.

摘要

经常注意到在镰状炭疽菌培养物中产生滴状液滴。因此，评估了内脏液滴的形成、内脏中毒素的渗出和内脏液滴的化学成分，以发现内脏的生态重要性。在测试的培养基中，在燕麦粉琼脂培养基和宿主提取物肉汤培养基中观察到更多的内脏。评估五种不同碳源对C. falcatum内脏的影响表明在固体培养基中，在葡萄糖、果糖和淀粉修正的培养基中观察到稀疏的滴落液滴，而在除果糖修正的培养基外的肉汤培养物中，没有其他碳源诱导菌丝体的滴落。滴孔现象仅在孢子形成的菌丝体中被注意到，并且它也遵循与孢子形成相关的特定模式。甘蔗叶上的内脏渗出物的生物测定产生明显的坏死病变，具有与阳性对照相似的大黄色晕圈，从而证实了毒素的存在。浓度为 1000 ppm 的滴液在甘蔗叶上引发褐变症状，并在 10 000 ppm 时产生 3.7 cm 的明显坏死病灶。粗馏分的毒性在高达 60°C 的温度下是稳定的。粗滴液液滴的气相色谱-质谱 (GC-MS) 分析确定了 24 种化合物的存在，这些化合物属于脂肪酸、脂肪酸衍生物、类黄酮、黄酮苷、甾醇、醌衍生物、酰胺和乙二醇醚，以及其中的其中脂肪酸占主导地位。这两种化合物，即十六烷酸甲酯和 9-十八碳烯酸（Z ) 甲酯含量丰富（分别为 18.14% 和 17.98%）并被确定为可能的有毒化合物。