Molecular Detection of Candidatus Liberibacter asiaticus in Citrus Plants: Insights from Bangladesh

Citrus cultivation is vital to the agricultural landscape, offering substantial nutritional and economic advantages. However, citrus plants are highly vulnerable to numerous disorders, with Huanglongbing (HLB), commonly known as citrus greening disease, being one of the most severe threats. This devastating condition is attributed to the fastidious bacterium Candidatus Liberibacter asiaticus, which poses a significant risk to the citrus industry in Bangladesh. The primary transmission routes for this disease include insect vectors and the grafting of infected budwood. Recent advancements in diagnostic techniques have highlighted the polymerase chain reaction (PCR) method as a more reliable and sensitive approach for detecting the greening bacterium compared to traditional methods such as electron microscopy, DNA-DNA hybridization, and immunofluorescence. Research has shown that utilizing a DNA extraction kit for isolating DNA results in superior quality and quantity compared to other methods. In a study conducted at the Bangladesh Institute of Nuclear Agriculture in Mymensingh, researchers collected 10 samples from symptomatic trees, revealing that 4 samples (40%) tested positive for Candidatus Liberibacter asiaticus. The PCR analysis produced amplicons of 703 bp and 500 bp using primer pairs A2/J5 and LSS/LSS606, respectively. The findings from this study indicate that March is the optimal month for sampling when conducting PCR detection of the greening bacterium. The validated methodologies from this research will play a crucial role in implementing regulatory measures, effectively managing infected trees, and establishing a nursery system that is free from Candidatus Liberibacter asiaticus. The study concluded that the psyllid transmission of HLB is a complex and dynamic process that involves multiple interactions among biotic and abiotic factors. It is essential to focus on implementing measures to combat this severe disease, which poses a risk to all citrus varieties in this biodiversity-rich region. Failure to do so could result in significant challenges for revitalizing citrus cultivation. These efforts are essential for safeguarding the future of citrus cultivation in Bangladesh and mitigating the economic impacts associated with HLB.