BACKGROUND Penicillium digitatum is one of the most important pathogens causing citrus green mold, leading to significant economic losses. Traditionally, synthetic fungicides are used to control diseases. However, the side effects of fungicides should not be ignored. Thus, antagonistic yeasts were proposed to be safe and effective alternatives to manage diseases. Orchards are excellent sources of naturally occurring antagonists against pathogens. Therefore, antagonistic yeasts obtained from orchards were screened, and the possible biocontrol mechanisms of the most promising yeast were investigated. RESULTS Seventy-eight isolates of yeasts (15 species of 10 genera) were obtained from citrus orchards. In in vitro assays, 16 strains showed antifungal activity against P. digitatum and 15 strains showed biocontrol potential against green mold on Olinda oranges. Pichia galeiformis (BAF03) exhibited the best antagonistic activity against P. digitatum during 6 days storage at 25 °C and a good antagonistic activity during 29 days at 4 °C. P. galeiformis (BAF03) could colonize and amplify quickly in wounded citrus. Scanning electron microscopy (SEM) results showed that the citrus wound was colonised by the yeast. A total of 8 VOCs were identified by Gas Chromatography-Mass Spectrometry (GC-MS). The volatile organic compounds (VOCs) produced by P. galeiformis (BAF03) efficiently inhibited P. digitatum. CONCLUSION P. galeiformis (BAF03) isolated from a citrus orchard showed potential to control postharvest green mold of citrus. The possible mechanisms of action likely include competition for space and nutrients as well as production of VOCs. This article is protected by copyright. All rights reserved.

中文翻译：

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柑橘绿色霉菌拮抗酵母的筛选及可能的 Pichia galeiformis (BAF03) 生防机制

背景技术指状青霉是引起柑橘绿霉病的最重要病原体之一，造成重大经济损失。传统上，合成杀菌剂用于控制疾病。但是，杀菌剂的副作用也不容忽视。因此，拮抗酵母被认为是控制疾病的安全有效的替代品。果园是天然存在的对抗病原体的拮抗剂的极好来源。因此，筛选了从果园中获得的拮抗酵母，并研究了最有前途的酵母可能的生防机制。结果 从柑橘园中获得了 78 株酵母菌（10 属 15 种）。在体外试验中，16 株菌株对 P. digitatum 和 15 个菌株显示出对 Olinda 橙子上的绿色霉菌的生物防治潜力。Pichia galeiformis (BAF03) 在 25 °C 下储存 6 天期间表现出对 P. digitatum 的最佳拮抗活性，在 4 °C 下 29 天期间具有良好的拮抗活性 galeiformis (BAF03) 可以在受伤的柑橘中快速定殖和扩增。扫描电子显微镜 (SEM) 结果显示柑橘伤口被酵母菌定植。气相色谱-质谱联用 (GC-MS) 共鉴定了 8 种 VOC。P. galeiformis (BAF03) 产生的挥发性有机化合物 (VOC) 有效地抑制了 P. digitatum。结论 从柑橘园中分离的 P. galeiformis (BAF03) 显示出控制柑橘采后绿色霉菌的潜力。可能的作用机制可能包括空间和营养的竞争以及 VOC 的产生。本文受版权保护。版权所有。