Rapid, Sensitive, and Carryover Contamination-Free Loop-Mediated Isothermal Amplification-Coupled Visual Detection Method for ‘Candidatus Liberibacter asiaticus’

• Published in: Journal of agricultural and food chemistry Vol. 65; no. 38; pp. 8302 - 8310
• Main Authors: Qian, Wenjuan, Meng, Youqing, Lu, Ying, Wu, Cui, Wang, Rui, Wang, Liu, Qian, Cheng, Ye, Zunzhong, Wu, Jian, Ying, Yibin
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 27.09.2017
• Subjects: Citrus - chemistry; Citrus - microbiology; Luminescent Measurements - methods; Nucleic Acid Amplification Techniques - methods; Organic Chemicals - chemistry; Plant Diseases - microbiology; Plant Leaves - chemistry; Plant Leaves - microbiology; Rhizobiaceae - chemistry; Rhizobiaceae - genetics; Rhizobiaceae - isolation & purification; crude DNA extraction; huanglongbing; Candidatus Liberibacter asiaticus; visual detection; field detection; isothermal amplification
• ISSN: 0021-8561; 1520-5118
• DOI: 10.1021/acs.jafc.7b03490

Huanglongbing is a devastating citrus disease, and ‘Candidatus Liberibacter asiaticus’ (Las) is the most prevalent huanglongbing-associated bacterium. Its field detection remains challenging. In this work, a visual, rapid, sensitive, and carryover contamination-free method was developed for field detection of Las. Leaf samples were treated with 500 μL of 0.5 M sodium hydroxide solution for 3 min, and 50-fold dilutions were directly amplified by loop-mediated isothermal amplification. Then, a novel SYTO-9-based visual detection method was used to evaluate amplification results without uncapping operation. Negative samples remained colorless, while positive samples generated obvious green fluorescence, which could be easily distinguished by the naked eye with a mini-fluorescent-emission cartridge developed originally. The proposed detection method could be accomplished within 40 min and is about 100 times more sensitive than conventional TaqMan polymerase chain reaction. The reliability of this method was also verified by analyzing practical samples.