Department of Plant Pathology, University of Florida, Gainesville, Florida, USA.
Gulf Coast Research and Education Center, University of Florida, Wimauma, Florida, USA.
Environ Microbiol. 2021 Oct;23(10):5850-5865. doi: 10.1111/1462-2920.15541. Epub 2021 Jun 8.
Bacterial spot caused by Xanthomonas perforans (Xp) is an economically important disease in tomato. Previous studies have shown that the recently isolated Xp strains have acquired and retained the effector gene, xopJ2, which has been reported to increase fitness of the pathogen in the field. To elucidate the fitness benefit of xopJ2, we quantified the effect of xopJ2 on the dispersal and evolution of Xp populations on tomato. We compared movement of two wild-type Xp strains expressing xopJ2 to their respective xopJ2 mutants when co-inoculated in the field. We developed a binary logistic model to predict the presence of Xp over spatial and temporal dimensions with or without xopJ2. Based on the model, wild-type bacteria were dispersed approximately three times faster than the xopJ2 mutants. In a simulation experiment, the selective advantage due to increased dispersal velocity led to an increase in the frequency of xopJ2 gene in the Xp population and its apparent fixation within 10 to 12 cropping seasons of the tomato crop. Our results show that the presence of a single gene can affect the dispersal of a bacterial pathogen and significantly alter its population dynamics.
由穿孔黄单胞菌（Xp）引起的细菌性斑点是番茄上一种经济上重要的疾病。先前的研究表明，最近分离到的 Xp 菌株已经获得并保留了效应子基因 xopJ2，据报道，该基因增加了病原体在田间的适应性。为了阐明 xopJ2 的适应优势，我们量化了 xopJ2 对番茄上 Xp 种群扩散和进化的影响。我们比较了在田间共同接种时表达 xopJ2 的两种野生型 Xp 菌株与其各自的 xopJ2 突变体的运动情况。我们开发了一个二元逻辑模型来预测有无 xopJ2 时 Xp 在空间和时间维度上的存在。基于该模型，野生型细菌的扩散速度大约是 xopJ2 突变体的三倍。在模拟实验中，由于扩散速度增加而产生的选择优势导致 Xp 种群中 xopJ2 基因的频率增加，并在番茄作物的 10 到 12 个种植季节内明显固定。我们的结果表明，单个基因的存在可以影响细菌病原体的扩散，并显著改变其种群动态。
