Phytophthora blight is the most devastating disease for pepper (Capsicum annuum L.) production and is caused by Phytophthora capsici. Current management strategies are not effective. Our study assessed the multi-trait effects of Paenibacillus polymyxa, which suppresses Phytophthora blight and promotes plant growth in pepper plants. A total of 82 bacterial strains isolated from rhizosphere soil of pepper plants were screened for in vitro inhibition of P. capsici growth. The results revealed that only six strains showed strong antagonistic activity against P. capsici. These six strains were used for controlling Phytophthora blight in pepper by seedling assays under greenhouse conditions. Three strains showed a lower incidence of Phytophthora blight and were used in further growth-promoting and biocontrol studies under greenhouse conditions. Strain YCP16-23 showed >60.0% suppression of P. capsici and significantly promoted growth of pepper plants compared to the untreated control. Based on cultural and morphological characterization and 16S rRNA gene sequencing, strain YCP16-23 was identified as Paenibacillus polymyxa. Strain YCP16-23 demonstrated many characteristics that are beneficial for plants, such as production of α-amylase, ammonia, cellulase, indole-3-acetic acid, pectinase, siderophores, and protease, as well as solubilization of phosphate. In a two-year field trial, strain YCP16-23 exhibited remarkable disease suppressing effect by controlling Phytophthora blight (76.24% and 38.09% in years 2017 and 2018, respectively) compared with the untreated control. Strain YCP16-23 caused disease suppression comparable to the microbial fungicides ‘Cike’ (72.04% and 15.41%) and Fluazinam (80.47% and 5.24%). Overall, the results suggest that strain YCP16-23 could provide protection against Phytophthora blight via direct and indirect modes of action and can be used as a biocontrol agent.

中文翻译：

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多粘类芽孢杆菌YCP16-23株对辣椒植株的促生抑病作用

疫霉疫病是辣椒 (Capsicum annuum L.) 生产中最具破坏性的疾病，由辣椒疫霉引起。当前的管理策略无效。我们的研究评估了多粘类芽孢杆菌的多性状效应，其抑制疫霉病并促进辣椒植物的植物生长。从辣椒植物的根际土壤中分离出的总共 82 株细菌菌株被筛选用于体外抑制辣椒生长的菌株。结果表明，只有 6 个菌株对辣椒疫霉表现出强烈的拮抗活性。通过在温室条件下的幼苗测定，这六个菌株用于控制辣椒中的疫霉疫病。三个菌株显示出较低的疫霉病发生率，并被用于温室条件下的进一步促生长和生物防治研究。与未处理的对照相比，菌株 YCP16-23 显示出 >60.0% 的辣椒素抑制并显着促进了辣椒植物的生长。基于培养和形态特征以及16S rRNA基因测序，菌株YCP16-23被鉴定为多粘类芽孢杆菌。菌株 YCP16-23 表现出许多对植物有益的特性，例如产生 α-淀粉酶、氨、纤维素酶、吲哚-3-乙酸、果胶酶、铁载体和蛋白酶，以及溶解磷酸盐。在为期两年的田间试验中，与未处理的对照相比，菌株 YCP16-23 通过控制疫霉病（2017 年和 2018 年分别为 76.24% 和 38.09%）表现出显着的疾病抑制作用。菌株 YCP16-23 引起的疾病抑制与微生物杀菌剂 'Cike' 相当（72.04% 和 15. 41%) 和氟啶胺 (80.47% 和 5.24%)。总体而言，结果表明菌株 YCP16-23 可以通过直接和间接的作用方式提供对疫霉疫病的保护，并可用作生物防治剂。