Endophytic and rhizosphere-competent entomopathogenic fungi (EF) are important plant bodyguards, although the mechanisms underlying this phenomenon are poorly understood. Therefore, we aimed to elucidate the roles of antibiosis (lethal and sublethal effects), and potential growth compensation (in response to leaf injury) in melon plants exposed to cotton leafworm. Plants were inoculated with one of three EF strains (EAMa 0158-Su Metarhizium brunneum strain or EABb 04/01-Tip and EABb 01/33-Su Beauveria bassiana strains) by either foliar spray, seed dressing or soil drenching and then challenged with either multiple short-term, or single long-term Spodoptera littoralis larval infestation. Endophytic colonization and relative expression of plant defense genes were tracked using molecular techniques alongside evaluation of antibiosis effects on S. littoralis and plant tolerance to larval-induced leaf injuries. Inoculated plants exhibited antibiosis and potential growth compensation in responses to various S. littoralis challenges, which resulted in increased fresh and dry weight, chlorophyll content, number of secondary branches and stem diameter. Furthermore, up-regulation in the relative expression of ethylene (ACO1, ACO3, EIN2, EIN3) and jasmonic acid (LOX2)-related genes were observed, with the endophytic B. bassiana- induction of ethylene and jasmonic acid production being higher in S. littoralis infested plants. Our findings strongly confirm the EF multifunctionality and the involvement of the Endophytic EF triggered melon defensive system induction in the antibiosis and compensatory growth to protect melon plants from pest damage.

内生和根际昆虫病原真菌（EF）是重要的植物保镖，尽管人们对这种现象背后的机制知之甚少。因此，我们的目的是阐明抗生素（致死和亚致死效应）的作用，以及暴露于棉叶虫的瓜类植物中潜在的生长补偿（响应叶子损伤）。通过叶面喷雾、拌种或土壤淋洗，用三种 EF 菌株之一（EAMa 0158-Su Metarhizium brunneum 菌株或 EABb 04/01-Tip 和 EABb 01/33-Su Beauveria bassiana 菌株）接种植物，然后用以下任一菌株进行攻击：多次短期或单一长期的斜纹夜蛾幼虫侵扰。使用分子技术追踪植物防御基因的内生定殖和相对表达，同时评估对北沙滨的抗菌作用和植物对幼虫引起的叶片损伤的耐受性。接种的植物在应对各种北沙蚕挑战时表现出抗菌和潜在的生长补偿，从而导致鲜重和干重、叶绿素含量、次生分枝数量和茎直径增加。此外，观察到乙烯（ACO1、ACO3、EIN2、EIN3）和茉莉酸（LOX2）相关基因的相对表达上调，内生白僵菌诱导的乙烯和茉莉酸产量在白僵菌中更高。 . 北沙蚕侵染植物。我们的研究结果有力地证实了 EF 的多功能性以及内生 EF 的参与触发了甜瓜防御系统诱导抗菌和补偿性生长，以保护甜瓜植物免受害虫损害。