Maize (Zea mays) has economic and cultural importance worldwide. It is a highly domesticated plant commonly attacked by several pathogens, among them Bipolaris maydis, having potential to cause damages to the crop development and yields. This study aimed to investigate the plant’s defense mechanisms that could be associated with their resistance to the pathogen. In a greenhouse, four maize genotypes (P1630H, AG3700, SCS156 Colorado and 30K75Y) with different levels of resistance to the fungus were examined. In the phenological stage V4, the plants were inoculated with B. maydis (1 × 10³ conidia.mL⁻¹), and the severity of the disease was evaluated after ten days. Leaf samples were collected right before inoculation (0 h), and at 36, 72, 108 and 144 h after inoculation for determination of the peroxidase (POX), phenylalanine ammonia-lyase (PAL) and lipoxygenase (LOX) enzyme activity, as well as the content of phenolic compounds and flavonoids. The germination rate and formation of appressoria of B. maydis on the leaf surface of the four genotypes were also evaluated. Cultivar AG3700 exhibited a low disease severity, the highest activity of the POX and PAL and, on its leaf surface, a lesser degree of conidia germination and formation of double appressoria were observed. The activity of the POX and PAL enzymes and of antimicrobial compounds on maize resistance to B. maydis is discussed.

玉米（Zea mays）在世界范围内具有经济和文化重要性。它是一种高度驯化的植物，通常会受到多种病原体的攻击，其中包括玉米双歧杆菌，有可能对作物的发育和产量造成损害。这项研究旨在调查植物的防御机制，这些机制可能与其对病原体的抗性有关。在温室中，检测了对真菌具有不同抗性水平的四种玉米基因型（P1630H、AG3700、SCS156 Colorado 和 30K75Y）。在物候阶段V4，植物接种B. maydis (1 × 10 ³ conidia.mL ^-1)，并在十天后评估疾病的严重程度。在接种前（0 小时）和接种后 36、72、108 和 144 小时收集叶片样品，用于测定过氧化物酶 (POX)、苯丙氨酸解氨酶 (PAL) 和脂氧合酶 (LOX) 酶的活性，以及如酚类化合物和黄酮类化合物的含量。还对四种基因型的玉米芽孢杆菌的发芽率和附着胞的形成进行了评价。栽培品种 AG3700 表现出较低的疾病严重性，POX 和 PAL 的活性最高，并且在其叶片表面，观察到较小程度的分生孢子萌发和双附着胞的形成。POX 和 PAL 酶以及抗微生物化合物对玉米对B. maydis抗性的活性被讨论。