Sugarcane leaf scald caused by the bacterium Xanthomonas albilineans is a major disease of sugarcane worldwide. Whereas erratic symptoms make phenotypic detection challenging, molecular methods require expensive instruments and labour, and longer sample-to-answer times. We report a novel method for detection of X. albilineans DNA in sugarcane xylem sap. The method involves (i) boiling lysis-based DNA extraction from sugarcane sap; (ii) magnetic purification of target sequences directly from the lysate through use of magnetic bead-bound capture probes; and (iii) DNA sandwich hybridisation platform for HRP/TMB/H₂O₂ reaction-based naked eye visualisation and electrochemical detection of the target. The method is sensitive (limit of detection 100 fM) and reproducible (relative standard deviation <7%) with linear dynamic range 100 fM–1 nM (R² = 0.99). The method was tested on a range of sugarcane cultivars of known resistance ratings (susceptible, intermediate resistant, and resistant) for leaf scald disease from an inoculated field trial. Detection levels agreed with the resistance rating of cultivars tested. In addition, qPCR results strongly correlated with our assay (r = 0.91–0.99, P < 0.01) and cultivar resistance rating. We believe that our assay could be useful for rapid screening as well as sensitive quantification of target pathogen DNA in infected sugarcane plants.

由白线黄单胞菌引起的甘蔗叶烫伤是世界范围内甘蔗的主要病害。尽管不稳定的症状使表型检测具有挑战性，但分子方法需要昂贵的仪器和劳动力，以及更长的样本到回答时间。我们报告了一种新的检测甘蔗木质部汁液中白线单胞菌DNA 的方法。该方法包括 ( i ) 从甘蔗汁液中提取基于裂解的 DNA；( ii ) 通过使用磁珠结合捕获探针直接从裂解物中磁性纯化目标序列；( iii ) HRP/TMB/H ₂ O ₂ DNA夹心杂交平台基于反应的肉眼可视化和目标的电化学检测。该方法灵敏（检测限为 100 fM）且可重现（相对标准偏差 <7%），线性动态范围为 100 fM–1 nM ( R ² = 0.99)。该方法在一系列已知抗性等级（易感、中等抗性和抗性）的甘蔗栽培品种上进行了测试，该品种对来自接种田间试验的叶烫伤病有抵抗力。检测水平与测试品种的抗性等级一致。此外，qPCR 结果与我们的分析密切相关（r = 0.91–0.99，P< 0.01) 和品种抗性等级。我们相信，我们的检测方法可用于快速筛选以及对受感染的甘蔗植物中的目标病原体 DNA 进行灵敏定量。