In this work, we have established a metabolite-based mass spectrometry (MS) method for rapid detection of HLB in navel orange trees.  Without sample pretreatment, characteristic mass spectra can be directly obtained from the raw plant samples using the direct MS method.  By monitoring and comparisons of the healthy and infected plants throughout a whole year, characteristic MS peaks of metabolites are found to be specific responses from infected plants and, thus, could be used as biomarkers for detection of HLB.  Therefore, HLB could be directly detected in the asymptomatic samples, such as stems, using this metabolite-based direct MS method.  In addition, principal component analysis and partial least squares discriminant analysis modes of metabolites from healthy and infected trees were established for investigating differentiation and seasonal variations of HLB in leaves, veins, and stems, providing valuable information for understanding the HLB in different seasons.
MS
In this work, we have established a metabolite-based mass spectrometry (MS) method for rapid detection of HLB in navel orange trees.  Without sample pretreatment, characteristic mass spectra can be directly obtained from the raw plant samples using the direct MS method.  By monitoring and comparisons of the healthy and infected plants throughout a whole year, characteristic MS peaks of metabolites are found to be specific responses from infected plants and, thus, could be used as biomarkers for detection of HLB.  Therefore, HLB could be directly detected in the asymptomatic samples, such as stems, using this metabolite-based direct MS method.  In addition, principal component analysis and partial least squares discriminant analysis modes of metabolites from healthy and infected trees were established for investigating differentiation and seasonal variations of HLB in leaves, veins, and stems, providing valuable information for understanding the HLB in different seasons.
MS