The phytopathogenic fungus Ustilago maydis causes corn smut by suppressing host plant defenses, including the oxidative burst response. While many studies have investigated how U. maydis responds to oxidative stress during infection, the consequences of heightened resistance to oxidative stress on virulence remain understudied. This study aimed to identify the effects on virulence in U. maydis strains exhibiting enhanced resistance to hydrogen peroxide (H₂O₂).

To achieve this, we exposed U. maydis SG200 to 20 escalating H₂O₂ shocks, resulting in an adapted strain resistant to concentrations as high as 60 mM of H₂O₂, a lethal dose for the initial strain. Genetic analysis of the adapted strain revealed five nucleotide substitutions, two minor copy number variants, and a large amplification event on chromosome nine (1–149 kb) encompassing the sole catalase gene. Overexpressing catalase increased resistance to H₂O₂; however, this resistance was lower than that observed in the adapted strain. Additionally, virulence was reduced in both strains with enhanced H₂O₂ resistance.

In summary, enhanced H₂O₂ resistance, achieved through either continuous exposure to the oxidative agent or through catalase overexpression, decreased virulence. This suggests that the response to the oxidative stress burst in U. maydis is optimal and that increasing the resistance to H₂O₂ does not translate into increased virulence. These findings illuminate the intricate relationship between oxidative stress resistance and virulence in U. maydis, offering insights into its infection mechanisms.

植物病原真菌玉米黑粉菌通过抑制宿主植物的防御（包括氧化爆发反应）引起玉米黑穗病。尽管许多研究已经调查了玉米玉斑病在感染过程中如何对氧化应激做出反应，但氧化应激抵抗力增强对毒力的影响仍未得到充分研究。本研究旨在确定对过氧化氢 (H ₂ O _{2 ) 抗性增强的玉米}U. 玉米菌株毒力的影响。

为了实现这一目标，我们将玉米 U. maydis SG200 暴露于 20 次逐渐升高的 H ₂ O ₂冲击中，产生了能够抵抗高达 60 mM H ₂ O ₂浓度（初始菌株的致死剂量）的适应性菌株。对适应菌株的遗传分析揭示了五个核苷酸取代、两个次要拷贝数变异以及包含唯一过氧化氢酶基因的九号染色体（1-149 kb）上的大扩增事件。_{过氧化氢酶的过度表达增加了对H 2} O ₂的抵抗力；然而，这种抵抗力低于在适应菌株中观察到的抵抗力。_{此外，两种菌株的毒力均因 H 2} O ₂抗性增强而降低。

总之，通过连续暴露于氧化剂或通过过氧化氢酶过度表达来增强H ₂ O _{2抗性，降低毒力。}这表明玉蜀黍对氧化应激爆发的反应是最佳的，并且增加对 H ₂ O ₂的抗性并不会转化为毒力的增加。这些发现阐明了玉米须菌的氧化应激抵抗力和毒力之间的复杂关系，为其感染机制提供了见解。