Document Type : Plant Pathology
Authors
1
Plant Protection Research Department, Fars Agricultural and Natural Resources Research and Education Center, Zarghan, Iran.
2
Plant Protection Research Department, Hormozgan Agricultural and Natural Resources Research and Education Center, Bandar Abbas, Iran
3
Plant Protection Research Department, Hormozgan Agricultural and Natural Resources Research and Education Center, Bandar Abbas, Iran.
4
Department of Plant Pathology, College of Agronomy Sciences, Sari Agricultural and Natural Resources University, Sari, Iran
5
: Department of Plant Protection, College of Agriculture, Shiraz University, Shiraz, Iran
6
Plant Protection Research Department, Fars Agricultural and Natural Resources Research and Education Center
10.22092/jaep.2026.371530.1563
Abstract
Over the past decade, symptoms of abnormal fruit coloration and deformation have been observed in mandarin (Citrus reticulata) trees in the Siyahoo region of Hormozgan Province, resulting in significant economic losses due to reduced marketability. To investigate the potential involvement of phloem-limited prokaryotes (Candidatus Liberibacter asiaticus, Candidatus Phytoplasma spp., and Spiroplasma citri), forty symptomatic and five asymptomatic trees were examined. Sampling was primarily conducted on the peduncles of symptomatic fruits, and DNA was extracted from both peduncles and midribs. Molecular detection of the target pathogens was performed using PCR assays with specific primer sets. Results revealed that Ca. Liberibacter asiaticus, the causal agent of the Asian form of citrus huanglongbing (HLB), was consistently identified in all trees exhibiting fruit discoloration and deformation. In contrast, phytoplasmas were not detected in any symptomatic trees, while Spiroplasma citri, the causal agent of citrus stubborn disease, was identified in only four trees with symptomatic fruits and leaves. None of these pathogens were detected in the five asymptomatic trees. Sequencing of selected PCR products, BLAST search and phylogenetic analyses confirmed the presence of Ca. L. asiaticus in symptomatic trees. Overall, PCR detection demonstrated a strong association between Ca. L. asiaticus and fruit malformation and uneven coloration, confirming the presence and spread of HLB in mandarin orchards of the Siyahoo region.
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