Fig. 1. CLas infection causes ROS production, callose deposition, and starch accumulation in young citrus leaves.

a Quantification of H₂O₂ in young leaves of 2-year-old HLB positive and healthy C. sinensis “Valencia” trees. Data shown are mean ± SEM, n = 4. b Quantification of callose depositions of young leaves by staining with aniline blue and observed under an epifluorescence microscope. Data shown are mean ± SEM, n = 10. Callose depositions were counted from ten leaves from five trees. c Starch content in young flush. Data shown are mean ± SEM, n = 4. HLB positive and healthy 2-year-old C. sinensis “Valencia” trees were trimmed to trigger young flush in the greenhouse. qPCR was conducted to quantify CLas titers in newly emerged leaves at different time points after bud initiation. Experiments were repeated twice with similar results. *, **, and *** indicate p value < 0.05, 0.01, and 0.001, respectively, compared with healthy young leaves and calculated using two-tailed Student’s t test. Source data are provided as a Source Data file.