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Abstract：
Pseudomonas syringae pv. syringae (Pss) is an emerging phytopathogen that causes Pseudomonas leaf spot (PLS) disease in pepper plants. Pss can cause serious economic damage to pepper production, yet very little is known about the virulence factors carried by Pss that cause disease in pepper seedlings. In this study, Pss strains isolated from pepper plants showing PLS symptoms in Ohio between 2013 and 2021 (n = 16) showed varying degrees of virulence (Pss populations and disease symptoms on leaves) on 6-week-old pepper seedlings. In vitro studies assessing growth in nutrient-limited conditions, biofilm production, and motility also showed varying degrees of virulence, but in vitro and in planta variation in virulence between Pss strains did not correlate. Comparative whole-genome sequencing studies identified notable virulence genes including 30 biofilm genes, 87 motility genes, and 106 secretion system genes. Additionally, a total of 27 antimicrobial resistance genes were found. A multivariate correlation analysis and Scoary analysis based on variation in gene content (n = 812 variable genes) and single nucleotide polymorphisms within virulence genes identified no significant correlations with disease severity, likely due to our limited sample size. In summary, our study explored the virulence and antimicrobial gene content of Pss in pepper seedlings as a first step toward understanding the virulence and pathogenicity of Pss in pepper seedlings. Further studies with additional pepper Pss strains will facilitate defining genes in Pss that correlate with its virulence in pepper seedlings, which can facilitate the development of effective measures to control Pss in pepper and other related P. syringae pathovars.
OBJECTIVE: Pseudomonas leaf spot (PLS) caused by Pseudomonas syringae pv. syringae (Pss) causes significant losses to the pepper industry. Highly virulent Pss strains under optimal environmental conditions (cool-moderate temperatures, high moisture) can cause severe necrotic lesions on pepper leaves that consequently can decrease pepper yield if the disease persists. Hence, it is important to understand the virulence mechanisms of Pss to be able to effectively control PLS in peppers. In our study, in vitro, in planta, and whole-genome sequence analyses were conducted to better understand the virulence and pathogenicity characteristics of Pss strains in peppers. Our findings fill a knowledge gap regarding potential virulence and pathogenicity characteristics of Pss in peppers, including virulence and antimicrobial gene content. Our study helps pave a path to further identify the role of specific virulence genes in causing disease in peppers, which can have implications in developing strategies to effectively control PLS in peppers.
OBJECTIVE: Pseudomonas leaf spot (PLS) caused by Pseudomonas syringae pv. syringae (Pss) causes significant losses to the pepper industry. Highly virulent Pss strains under optimal environmental conditions (cool-moderate temperatures, high moisture) can cause severe necrotic lesions on pepper leaves that consequently can decrease pepper yield if the disease persists. Hence, it is important to understand the virulence mechanisms of Pss to be able to effectively control PLS in peppers. In our study, in vitro, in planta, and whole-genome sequence analyses were conducted to better understand the virulence and pathogenicity characteristics of Pss strains in peppers. Our findings fill a knowledge gap regarding potential virulence and pathogenicity characteristics of Pss in peppers, including virulence and antimicrobial gene content. Our study helps pave a path to further identify the role of specific virulence genes in causing disease in peppers, which can have implications in developing strategies to effectively control PLS in peppers.
摘要：
丁香假单胞菌pv。丁香（Pss）是一种新兴的植物病原体，可引起辣椒植物中的假单胞菌叶斑病（PLS）。Pss会对辣椒生产造成严重的经济损失，然而，人们对Pss携带的导致辣椒幼苗疾病的毒力因子知之甚少。在这项研究中,从2013年至2021年在俄亥俄州表现出PLS症状的辣椒植物中分离出的Pss菌株（n=16）在6周龄辣椒幼苗上表现出不同程度的毒力（Pss种群和叶子上的疾病症状）。在营养有限条件下评估生长的体外研究，生物膜生产，运动性也表现出不同程度的毒力，但是在体外和植物中，Pss菌株之间的毒力变化并不相关。比较全基因组测序研究确定了值得注意的毒力基因，包括30个生物膜基因，87个运动性基因，和106个分泌系统基因。此外,共发现27个耐药基因。基于基因含量变化（n=812个可变基因）和毒力基因内单核苷酸多态性的多变量相关分析和评分分析与疾病严重程度没有显着相关性。可能是由于我们的样本量有限。总之,我们的研究探索了辣椒幼苗中Pss的毒力和抗菌基因含量，这是了解辣椒幼苗中Pss的毒力和致病性的第一步。对其他辣椒Pss菌株的进一步研究将有助于确定Pss中与其在辣椒幼苗中的毒力相关的基因，这可以促进制定有效的措施来控制辣椒和其他相关丁香病种中的Pss。
目的：由丁香假单胞菌引起的假单胞菌叶斑病。丁香（Pss）对辣椒行业造成重大损失。在最佳环境条件下（低温-中等温度，高水分）会导致辣椒叶片严重的坏死病变，如果疾病持续存在，则会降低辣椒产量。因此，重要的是要了解Pss的毒力机制，以便能够有效地控制辣椒中的PLS。在我们的研究中,在体外，在植物中,并进行了全基因组序列分析，以更好地了解辣椒Pss菌株的毒力和致病性特征。我们的发现填补了有关辣椒中Pss的潜在毒力和致病性特征的知识空白，包括毒力和抗菌基因含量。我们的研究有助于为进一步确定特定毒力基因在辣椒致病中的作用铺平道路。这可能对制定有效控制辣椒PLS的策略有影响。
目的：由丁香假单胞菌引起的假单胞菌叶斑病。丁香（Pss）对辣椒行业造成重大损失。在最佳环境条件下（低温-中等温度，高水分）会导致辣椒叶片严重的坏死病变，如果疾病持续存在，则会降低辣椒产量。因此，重要的是要了解Pss的毒力机制，以便能够有效地控制辣椒中的PLS。在我们的研究中,在体外，在植物中,并进行了全基因组序列分析，以更好地了解辣椒Pss菌株的毒力和致病性特征。我们的发现填补了有关辣椒中Pss的潜在毒力和致病性特征的知识空白，包括毒力和抗菌基因含量。我们的研究有助于为进一步确定特定毒力基因在辣椒致病中的作用铺平道路。这可能对制定有效控制辣椒PLS的策略有影响。
