辣木叶黄酮对采后金桔青霉病的防治及机理研究

为考察辣木叶黄酮对采后金桔青霉病的防治效果,以意大利青霉菌为试验菌种,采用体外平板接菌试验和体内损伤接种试验研究辣木叶黄酮对金桔果实采后青霉病的抑制效果及其抑制机理。结果表明,辣木叶黄酮对意大利青霉菌具有良好的抑菌活性,其最小抑菌浓度(MIC)及最小杀菌浓度(MFC)分别为4.00和8.00 mg·mL^-1。扫描电镜(SEM)和透射电镜(TEM)结果表明,辣木叶黄酮会引起意大利青霉菌菌丝体的扭曲,明显改变青霉菌菌丝的形态,而胞内超微结构显示辣木叶黄酮会破坏其膜结构和细胞器,导致胞内内容物外流,胞内空洞化,进而引起菌体死亡;损伤接种结果表明,辣木叶黄酮处理可显著降低金桔的病斑直径并保持金桔硬度(P<0.05),同时提高苯丙氨酸解氨酶(PAL)和几丁质酶相关防御酶的活性,使果胶酶保持较低的活性,增强果实的抗病性。本研究结果对辣木叶黄酮在柑橘类水果采后贮藏保鲜的应用具有重要意义。

Prevention Effects of Flavonoids From Leaves of Moringa oleifera Lam. on Kumquats Postharvest Blue Mold and Its Possible Mechanism

In order to investigate the effects of flaonoids from Moringa leaves on postharvest kumquats, the inhibition effect and mechanism were studied by in vitro plate inoculation test and in vivo injury inoculation test with Penicillium italicum. The results showed that the flavonoids of moringa leaves significant inhibited Penicillium italicum with minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of 4.00 and 8.00 mg·mL^-1, respectively. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis showed that the flavonoids from leaves of Moringa oleifera could cause the distortion of mycelium, which changed obviously the morphology of Penicillium italicum hyphae. The intracellular morphological structure showed that the flavonoids could destroy the membrane structure and organelles, leading to the outflow of intracellular contents and intracellular hollowing, and causing bacteria death. The results of injury inoculation showed that the treatment of flavonoids from leaves of Moringa oleifera significantly reduced the diameter of kumquat lesions, and maintained the hardness of kumquat, while enhanced the activity of related defense enzymes, such as phenylalaninease (PAL) and chitinase. The activity of pectinase was low, which could enhance the disease resistance of the fruit. It is of great significance for the application of moringa flavone in the storage of citrus fruits after harvest.