Thioredoxins (Trxs) belong to a family of multifunctional redox proteins that is critical for maintaining and regulating the cellular redox environment during plant cell growth. Also, they are important for the development of plant's response to biotic and abiotic stress; however, the specific biological functions of h-type thioredoxins (Trxhs) in plants have not been fully elucidated. Herein, we investigated the role of LmTrxh2, a specific member of the Trxh family, in response to various biotic stress simulants, including mechanical wounding, exposure to jasmonic acid (JA), picolinic acid (PA), salicylic acid (SA), ethephon (ETP), and hydrogen peroxide (H₂O₂). We observed that LmTrxh2 transcripts were significantly upregulated upon exposure to these stress simulants. The characterization of enzymatic activity revealed that the recombinant LmTrxh2 protein functions as a disulfide reductase. While the role of Trx proteins in redox regulation is well known, their involvement in antimicrobial activity is still unexplored. Therefore, we assessed the antimicrobial effect of LmTrxh2 towards various microorganisms and observed a concentration-dependent inhibition of microbial growth. The minimum inhibitory and minimum bactericidal concentrations and the diameters of the inhibition zones were 40–1250 μg/mL, 40–1250 μg/mL, and 12.5–32.5 mm, respectively. In addition, we used previously developed LmTrxh2-transgenic tobacco lines and found that they showed enhanced resistance to fungal infections triggered by Fusarium graminearum and Aspergillus niger. This resistance was associated with an upregulation of known defense-related genes. Overall, our findings suggest that LmTrxh2 is responsive to multiple biotic stress simulants and plays a critical role in the basal resistance of plants to pathogen infections. These results highlight the potential of LmTrxh2 in the development of strategies to protect crops from various stress factors and emphasize its importance in the adaptation of plants to different stress conditions.

硫氧还蛋白 (Trxs) 属于多功能氧化还原蛋白家族，对于植物细胞生长过程中维持和调节细胞氧化还原环境至关重要。此外，它们对于植物对生物和非生物胁迫的反应的发展也很重要。然而，h型硫氧还蛋白（Trxhs）在植物中的具体生物学功能尚未完全阐明。在此，我们研究了 Trxh 家族的特定成员 LmTrxh2 在响应各种生物应激模拟物中的作用，包括机械损伤、暴露于茉莉酸 (JA)、吡啶甲酸 (PA)、水杨酸 (SA)、乙烯利(ETP)和过氧化氢(H ₂ O ₂ )。我们观察到，暴露于这些应激模拟物后，LmTrxh2 转录本显着上调。酶活性表征表明重组 LmTrxh2 蛋白具有二硫键还原酶的功能。虽然 Trx 蛋白在氧化还原调节中的作用众所周知，但它们在抗菌活性中的作用仍未被探索。因此，我们评估了 LmTrxh2 对各种微生物的抗菌作用，并观察到对微生物生长的浓度依赖性抑制。最低抑菌浓度为40~1250 μg/mL，最低杀菌浓度为40~1250 μg/mL，最低杀菌浓度为40~1250 μg/mL，抑菌圈直径为12.5~32.5 mm。此外，我们使用先前开发的LmTrxh2转基因烟草品系，发现它们对禾谷镰刀菌和黑曲霉引发的真菌感染表现出增强的抵抗力。这种抵抗力与已知的防御相关基因的上调有关。总的来说，我们的研究结果表明，LmTrxh2对多种生物胁迫模拟物有反应，并在植物对病原体感染的基础抵抗力中发挥着关键作用。这些结果凸显了LmTrxh2在制定保护作物免受各种胁迫因素影响的策略方面的潜力，并强调了其在植物适应不同胁迫条件方面的重要性。