Departamento de Química, Universidade Federal de São Carlos, CP 676, 13565-905, São Carlos, SP, Brazil.
Centro APTA Citros Sylvio Moreira, Instituto Agronômico, CP 04,13490-970, Cordeirópolis, SP, Brazil.
Rapid Commun Mass Spectrom. 2020 Sep;34 Suppl 3:e8745. doi: 10.1002/rcm.8745. Epub 2020 Apr 6.
Xylella fastidiosa causes citrus variegated chlorosis (CVC) in sweet orange trees. A diagnostic method for detecting CVC before the symptoms appear, which would inform citrus producers in advance about when the plant should be removed from the orchard, is essential for reducing pesticide application costs.
Chemometrics was applied to high-performance liquid chromatography diode array detector (HPLC-DAD) data to evaluate the similarities and differences between the chromatographic profiles. A liquid chromatography/atmospheric pressure chemical ionization mass spectrometry selected reaction monitoring (LC/APCI-MS-SRM) method was developed to identify the major compounds and to determine their amounts in all samples.
We evaluated the effect of this bacterium on the variation in the chemical profile in citrus plants. The organs of C. sinensis grafted on C. limonia were analyzed. Chemometrics was applied to the obtained data, and two major groups were differentiated. Flavonoids were observed in one group (leaves) and coumarins in the second (roots), both at higher concentrations in the plants with CVC symptoms than in those without the symptoms and those in the negative control. The rootstocks also interfered in the metabolism of the scion.
The developed LC/APCI-MS-SRM method for detecting CVC before the symptoms appear is simple and accurate. It is inexpensive, and many samples can be screened per hour using 1 mg of leaves. Knowledge of the influence of the rootstock on the chemical profile of the graft is limited. This study demonstrates the effect of the rootstock in synthesizing flavonoids and increasing its content in all parts of the graft.
韧皮部杆菌会引起甜橙黄脉病。在症状出现之前，有一种诊断方法可以检测出黄脉病，这可以让柑橘种植者提前知道何时应该将植株从果园中移除，对于降低农药使用成本至关重要。
应用化学计量学方法对高效液相色谱二极管阵列检测器（HPLC-DAD）数据进行分析，以评估色谱图谱之间的相似性和差异性。建立了液相色谱/大气压化学电离质谱选择反应监测（LC/APCI-MS-SRM）方法，以鉴定主要化合物并确定所有样品中的含量。
我们评估了这种细菌对柑橘植物化学特征变化的影响。对嫁接在枳橙上的甜橙植株的器官进行了分析。应用化学计量学方法对获得的数据进行了分析，结果分化出两个主要组。在一个组（叶片）中观察到类黄酮，在另一个组（根）中观察到香豆素，在有黄脉病症状的植株中，这两种物质的含量都高于没有症状和阴性对照的植株。砧木也会干扰接穗的代谢。
开发的 LC/APCI-MS-SRM 方法可在症状出现之前检测黄脉病，该方法简单、准确。成本低廉，每小时可以用 1 毫克叶片筛查多个样本。关于砧木对嫁接物化学特征的影响的知识有限。本研究表明，砧木在合成类黄酮和增加其在嫁接物所有部位的含量方面具有重要作用。
