Shu Chang, Jiao Wenxiao, Cui Kuanbo, Cao Jiankang, Jiang Weibo
College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China.
College of Food Science and Engineering, Qilu University of Technology, Jinan 250353, China.
Foods. 2025 Feb 23;14(5):761. doi: 10.3390/foods14050761.
The disease resistance and defense mechanisms induced by ursolic acid (UA) in apple fruit were studied in this paper. UA was directly mixed with potato dextrose agar and broth media to assay its antifungal activity in vitro. The results showed that UA exerted inherent antifungal activity and directly inhibited the in vitro growth and spore germination of . Its half-maximal inhibitory concentration for hyphal growth was 175.6 mg L. Apple fruit were immersed in UA solution, followed by inoculation with , to measure their disease response. The results demonstrated that UA induced significant disease resistance in apple fruit and that its mechanisms are multifaceted and associated with defensive and antioxidative enzymes and the phenylpropanoid pathway. Chitinase, β-1,3-glucanase, peroxidase, and polyphenol oxidase were activated and maintained at relatively high levels. The activities of enzymes and their metabolites in the phenylpropanoid pathway, including phenylalanine ammonia-lyase, cinnamate-4-hydroxylase, and 4-coumarate coenzyme A ligase were significantly increased; accordingly, total phenolics, flavonoid, and lignin contents were significantly increased. The activities of superoxide dismutase, ascorbate peroxidase, and glutathione reductase were enhanced upon UA treatment, while catalase activity was suppressed, which regulates hydrogen peroxide accumulation to defend against pathogens. These results suggest that UA induces defense responses against postharvest blue mold rot in apple fruit and that it may be a promising elicitor to induce fruit disease resistance to control postharvest decay.
本文研究了熊果酸（UA）诱导苹果果实产生的抗病性及防御机制。将UA直接与马铃薯葡萄糖琼脂和肉汤培养基混合，以测定其体外抗真菌活性。结果表明，UA具有内在的抗真菌活性，可直接抑制体外生长和孢子萌发。其对菌丝生长的半数抑制浓度为175.6 mg/L。将苹果果实浸入UA溶液中，然后接种，以测定它们的病害反应。结果表明，UA可诱导苹果果实产生显著的抗病性，其机制是多方面的，与防御和抗氧化酶以及苯丙烷途径有关。几丁质酶、β-1,3-葡聚糖酶、过氧化物酶和多酚氧化酶被激活并维持在相对较高的水平。苯丙烷途径中酶及其代谢产物的活性，包括苯丙氨酸解氨酶、肉桂酸-4-羟化酶和4-香豆酸辅酶A连接酶显著增加；相应地，总酚、类黄酮和木质素含量显著增加。UA处理后，超氧化物歧化酶、抗坏血酸过氧化物酶和谷胱甘肽还原酶的活性增强，而过氧化氢酶活性受到抑制，从而调节过氧化氢的积累以抵御病原体。这些结果表明，UA可诱导苹果果实对采后青霉腐烂产生防御反应，它可能是一种有前途的诱导剂，可诱导果实抗病性以控制采后腐烂。
