柑橘黄龙病症状与“Candidatus Liberibacter asiaticus”PCR检测结果的相关性分析

Correlationships between symptoms of citrus huanglongbing and PCR detection of 'Candidatus Liberibacter asiaticus'

柑橘黄龙病症状较为复杂,且因寄主品种、生长期、病程等因素而异。利用PCR检测其病原菌"Candidatus Liberibacter spp."是目前柑橘黄龙病诊断的可靠方法之一。分析柑橘黄龙病症状与PCR检测结果的相关性有助于提高黄龙病的田间诊断准确率。本研究结果表明,与PCR检测相比,根据症状诊断柑橘黄龙病具有较高的假阳性率(8.20%)和假阴性率(50%);通过分析1 839个样品的症状与病原PCR检测结果发现,表现为斑驳型黄化、均匀黄化和"绿岛"这3种叶部症状以及"红鼻子果"和畸形果这2种果实症状的PCR病原检出率高;具有斑驳和黄化、黄化和"绿岛"、"绿岛"和花叶等复合症状样品的PCR检测"Ca.L.asiaticus"的阳性率最高;直径小于1 cm的幼果中的"Ca.L.asiaticus"检测稳定性低。这些结果为更准确地通过症状诊断柑橘黄龙病提供了科学依据。

The symptoms of the destructive citrus Huanglongbing（HLB） are variable depending on citrus varieties,leaf ages,and the progression of disease.PCR is one of the most reliable methods in detecting the causal agent ＇Candidatus Liberibacter spp.＇ of citrus HLB.In comparision,diagnosis based directly on the symptoms has been proven to be not convincing,with a false positive rate of 8.20% and a false negative rate of 50% in this study.So,analysis of the relationship between citrus symptoms and PCR detection of the causal agent of HLB will improve diagnosis of this disease in the field.A total of 1 839 samples were collected to analyse the relationship of HLB-like symptoms and the presence of the pathogen by PCR.We found that leaf symptoms including blotchy mottle,evenly yellowing and ＇green island ＇,and fruit symptoms with ＇red nose ＇ and ＇mis-shaped ＇fruits were much more relevant to HLB than others,and that the positive detection rate of Ca.L.asiaticus＇ in samples with the combined symptoms of blotchy and yellowing,yellowing and green island,and green island＇ and zinc-deficiency-like was significant higher than that in other single-symptom samples.These results provide relatively accurate diagnosis methods in the field based on the typical HLB symptoms.