Inducing disease resistance in fruit is one of the mechanisms of antagonistic yeast. Antagonistic yeast induces disease resistance in postharvest fruit and delays fruit decay. In our study, tryptophan enhanced the ability to induce disease resistance in citrus fruit by against blue mold, sour rot, and green mold. The disease incidence of blue mold on the 5th d decreased by 16.6% compared with the treatment group. Conversely, the disease incidence of sour rot on the 9th d decreased by 10.0% relative to the group, and the disease incidence of green mold on the 4th d decreased by 20.0% compared with the group. Further validation revealed that and tryptophan-treated significantly induced the upregulation of genes related to the biosynthesis of salicylic acid and its transduction pathways, sugar metabolism, the shikimic acid pathway, MYB transcription factors, the phenylpropane biosynthesis pathway, pathogenesis-related proteins, and activated defense pathways in citrus fruit. Moreover, the genes induced by the tryptophan-treated group showed significantly higher expression than those in the –treated group alone. These genes are linked to the biosynthesis of disease-resistant compounds in citrus. The upregulation of genes showed an enhancement in the defense mechanisms of citrus fruit against biotic stress, enabling them to allocate more resources to withstand unfavorable conditions. Further verification was conducted to establish the connection between the stimulation of disease resistance in citrus fruit by and the synthesis of pulcherriminic acid (PA). Results obtained from inoculation in citrus fruit by the PA-deficient mutant strain Δ showed a significant increase in disease incidence compared with ; the disease incidence of blue mold was 16.6% higher than the –treated group alone on the 4th d; the disease incidence of sour rot was 19.4% higher on the 5th d; and the disease incidence of green mold was 16.7% higher on the 5th d. This suggests that PA impacts the effectiveness of in stimulating disease resistance in citrus fruits. Furthermore, the pulcherrimin secreted by was extracted, and it was discovered that PA extract significantly boosted the disease resistance of the fruit to blue and green molds. This suggests that PA produced by may play a role in yeast-induced disease resistance in citrus fruit.

中文翻译：

---

色氨酸处理柑橘梅奇氏酵母增强柑橘果实抗病性的机制

诱导果实抗病是拮抗酵母的作用机制之一。拮抗酵母可诱导采后果实的抗病性并延缓果实腐烂。在我们的研究中，色氨酸增强了柑橘类水果抗蓝霉病、酸腐病和绿霉病的能力。第5天蓝霉病发病率较治疗组下降16.6%。反之，酸腐病第9天的发病率较该组下降10.0%，绿霉病第4天的发病率较该组下降20.0%。进一步验证发现，色氨酸处理显着诱导水杨酸生物合成及其转导途径、糖代谢、莽草酸途径、MYB转录因子、苯丙烷生物合成途径、发病相关蛋白和活化相关基因的上调。柑橘类水果的防御途径。此外，色氨酸处理组诱导的基因表现出明显高于单独处理组的基因表达。这些基因与柑橘中抗病化合物的生物合成有关。基因的上调表明柑橘类水果对抗生物胁迫的防御机制得到增强，使它们能够分配更多的资源来抵御不利的条件。进一步验证了柑橘类水果抗病性的刺激与普切明酸（PA）的合成之间的联系。 PA缺陷突变株Δ接种柑橘类水果的结果显示，与 相比，发病率显着增加；第4天蓝霉病发病率比单独治疗组高16.6%；第5天酸腐病发病率增高19.4%；绿霉病发病率第5天增加16.7%。这表明 PA 影响刺激柑橘类水果抗病性的有效性。此外，还提取了其分泌的普切明，发现PA提取物显着增强了果实对蓝霉和绿霉的抗病能力。这表明 产生的 PA 可能在酵母诱导的柑橘类水果抗病性中发挥作用。