Godinez-Vidal Damaris, Franco-Navarro Francisco, Edwards Scott, Ploeg Antoon T, Groen Simon C
Department of Nematology, University of California, Riverside, CA 92521, USA.
Department of Botany and Plant Sciences, University of California, Riverside, CA 92521, USA.
bioRxiv. 2025 Jun 24:2025.06.18.660456. doi: 10.1101/2025.06.18.660456.
Tomato is a food crop of global importance, with a large proportion of processing tomatoes produced in California. One of the main problems plaguing tomato production is infection by populations of root-knot nematodes (RKNs; spp.) that can evade or suppress ('break') resistance mediated by the gene, which has been introgressed into most processing tomato cultivars. In this study, we evaluate fourteen spp. populations collected from fields across the state of California that can complete their life cycle on tomato cultivars. One of these populations was identified as and the others as . All RKN populations developed and reproduced on tomato cultivar 'Celebrity'. Although we did not observe differences in gall index among populations when studied together in greenhouse conditions, significant quantitative variation in reproduction factor values was apparent among them. Several pathogens and parasites display geographical gradients in aggressiveness and we identified a negative correlation between populations' latitudes-of-origin and reproduction factors. This suggests that populations of these thermophilic RKN species from lower latitudes tended to have evolved higher levels of aggressiveness on tomato, which may be linked to warmer temperatures throughout the year. Finally, populations with relatively low reproduction factor values still showed significant differences in the phenotypes of the galls they induced. Our results showed that populations evolved genetic variation in aggressiveness along a latitudinal gradient in Californian processing tomato agroecosystems, which may have implications for managing these important crop pests.
番茄是一种具有全球重要性的粮食作物，加利福尼亚州生产了很大一部分加工番茄。困扰番茄生产的主要问题之一是根结线虫（RKNs； spp.）种群的感染，这些线虫能够逃避或抑制（“突破”）由 基因介导的抗性，该基因已被导入大多数加工番茄品种中。在本研究中，我们评估了从加利福尼亚州各地田间收集的14个 spp. 种群，这些种群能够在 番茄品种上完成其生命周期。其中一个种群被鉴定为 ，其他种群被鉴定为 。所有RKN种群都在 番茄品种“Celebrity”上发育和繁殖。尽管我们在温室条件下共同研究时未观察到种群间在虫瘿指数上的差异，但它们在繁殖因子值上存在明显的数量变异。几种病原体和寄生虫在侵袭性方面呈现地理梯度，我们发现种群的原产地纬度与繁殖因子之间存在负相关。这表明来自较低纬度的这些嗜热RKN物种的种群在 番茄上往往进化出了更高水平的侵袭性，这可能与全年较温暖的温度有关。最后，繁殖因子值相对较低的种群在它们诱导的虫瘿表型上仍表现出显著差异。我们的结果表明，在加利福尼亚加工番茄农业生态系统中， 种群沿着纬度梯度在侵袭性方面进化出了遗传变异，这可能对管理这些重要的作物害虫具有重要意义。
