柑橘黄龙病菌在贡柑叶片中的分布分析

本研究从不同黄龙病症、叶片不同部位、不同树势三个方面综合分析贡柑叶片中黄龙病菌（Las）的分布。结果表明：（1）斑驳与均匀黄化是与黄龙病最相关的症状且斑驳黄化贡柑叶片中Las含量最高，缺锌黄化具有黄龙病阳性与阴性两种类型样品，无明显黄化症状但革质化的叶片中也含有Las且含量极高。（2）斑驳与均匀黄化典型黄龙病症的贡柑叶片中，Las的含量从叶尖到叶柄以及从叶片到主叶脉均呈现递增趋势，且主叶脉与叶柄的含量最高。（3）在感染初期顶端抽黄梢而下侧健康的病树中，Las的含量从发病严重的部位到树势强的部位呈现递减趋势。这些研究发现将为黄龙病症的田间诊断以及分子检测的样品采集提供有效线索，对黄龙病的有效防控具有重要意义。

Distribution of Candidatus Liberibacter asiaticus in the Leaves of Citrus reticulata Blanco var. Gonggan

In this study, a comprehensive analysis of titers distribution of Las in the leaves of Citrus reticulata Blanco var. Gonggan was carried out according to different symptoms, different part of leaves and different location of citrus trees. It was revealed that: (1) Blotchy mottle and evenly yellowing were the most relevant symptoms for HLB, and the titers of Las in blotchy mottle leaves were highest among other symptoms; Samples showing zinc-deficiency-like symptoms were either HLB-positive or HLB-negative; Thicken leaves showing no-typical symptoms were also infected with Las and the titers were high. (2) The Las titers in the typical blotchy mottle and evenly yellowing leaves distributed lower to higher level from the tip of the blade to the petiole and also from leaves to midribs, and the Las titers showed the highest level in midribs and the petiole. (3) The Las titers decreased from top section which expresses typical symptoms to lower section which expresses no HLB symptoms in citrus trees when infected with HLB at the early stage. These data will provide rewarding clues for field diagnosis of HLB and also for sample collection for molecular detection of HLB, thus to provide basis for effective control of HLB.