Department of Plant Pathology, Faculty of Agriculture, Zagazig University, Zagazig, Egypt.
Biochemistry Department, Faculty of Agriculture, Zagazig University, Zagazig, Egypt.
Pest Manag Sci. 2021 Jul;77(7):3313-3324. doi: 10.1002/ps.6375. Epub 2021 Apr 5.
Cucumber plants suffer from a serious threatening disease, downy mildew, throughout the growing seasons irrespective of the weather temperature. The causal agent, Pseudoperonospora cubensis, tends to evolve rapidly upon sequential applications of chemical fungicides and generate new progeny possessing tolerance to such fungicides. Glycoproteins represent an environmentally safe alternative for chemically synthetized fungicides and do not trigger fungicide resistance. We studied the antifungal activity of four glycoproteins namely soybean β-conglycinin, chickpea vicilin, duck egg ovomucin and catfish p22 against P. cubensis. Ten commercial fungicides of different chemical groups were used as positive controls of glycoprotein treatments.
The results revealed that soybean β-conglycinin and catfish p22 glycoproteins possess significant antifungal activity against P. cubensis. The amount of disease suppression caused by β-conglycinin and p22 was comparable to the highly efficient chemical fungicides containing copper oxychloride, cymoxanil and fosetyl Al as active ingredients. Vicilin and ovomucin were less efficient biocides as they gave moderate suppression of disease severity. However, all tested glycoproteins provided full protection for the newly emerged cucumber leaves. Microscopic examination of glycoprotein-treated leaves inferred the ability of catfish p22 and soybean β-conglycinin to disrupt the integrity of sporangial cell walls of P. cubensis rendering them non-viable compared to untreated ones. Expression levels of total phenolic compounds and the antioxidant enzymes catalase, superoxide dismutase and peroxidase were elevated upon glycoproteins application, which infers their involvement in disease suppression.
This report emphasizes the direct and indirect roles of glycoproteins in safe management of cucumber downy mildew disease. © 2021 Society of Chemical Industry.
黄瓜植株在整个生长季节都会遭受严重的病害，如霜霉病，无论天气温度如何。病原菌古巴假霜霉菌容易在连续使用化学杀菌剂后迅速进化，并产生对这些杀菌剂具有耐受性的新后代。糖蛋白是化学合成杀菌剂的一种环保替代品，不会引发杀菌剂抗性。我们研究了四种糖蛋白，即大豆β-伴球蛋白、鹰嘴豆豆球蛋白、鸭蛋卵粘蛋白和鲶鱼 p22 对古巴假霜霉菌的抑菌活性。十种不同化学基团的商业杀菌剂被用作糖蛋白处理的阳性对照。
结果表明，大豆β-伴球蛋白和鲶鱼 p22 糖蛋白对古巴假霜霉菌具有显著的抑菌活性。β-伴球蛋白和 p22 引起的病害抑制量与含氧氯化铜、霜脲氰和乙膦铝作为有效成分的高效化学杀菌剂相当。豆球蛋白和卵粘蛋白的杀菌效果较差，因为它们只能适度抑制病害严重程度。然而，所有测试的糖蛋白都能为新出现的黄瓜叶片提供完全的保护。对糖蛋白处理叶片的显微镜检查推断，鲶鱼 p22 和大豆β-伴球蛋白能够破坏古巴假霜霉菌的孢子囊细胞壁的完整性，使它们变得不可生存，而未处理的孢子囊则保持完整。糖蛋白处理后，总酚类化合物和抗氧化酶过氧化氢酶、超氧化物歧化酶和过氧化物酶的表达水平升高，这表明它们参与了病害抑制。
本报告强调了糖蛋白在安全管理黄瓜霜霉病中的直接和间接作用。© 2021 化学工业协会。
