Huanglongbing (HLB) also known as citrus greening, is a destructive disease of citrus and now, is considered as a new emergence and spread out threat to the Middle East and North Africa (MENA) citrus production. In a survey conducted in southern Iran in 2013-2014, 77 citrus samples exhibiting symptoms of HLB were collected. Single-step and nested polymerase chain reactions (PCR) were employed to determine the presence of the phloem-limited bacterial pathogens ‘Candidatus Liberibacter asiaticus’(CLas), phytoplasma and Spiroplasma citri. Both CLas and phytoplasma were detected in HLB-affected citrus trees as co-infection (7.79%) and single infection (10.38% for phytoplasma and 42.85% for CLas). According to the proposed 16S rDNA-based phytoplasma classification scheme, the HLB-associated phytoplasma from this study was a member of peanut witches’broom (16SrII) phytoplasma group. This is the first report of association of a phytoplasma with HLB in sweet lime in the world and first record of association of CLas with sour orange (Citrus aurantium L.) and sweet lime in Iran.

Keywords: 'Candidatus Liberibacter asiaticus', Citrus greening, Phytoplasma, Citrus, Iran

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