Comparison of the starch-iodine reaction technique with the Recombinase Polymerase Amplification for citrus Huanglongbing (HLB) diagnosis
Huanglongbing (HLB) is one of the most important citrus diseases worldwide. A field level diagnosis is difficult when it is based on visual symptoms, since they can be confused with similar symptoms of other diseases or nutritional deficiencies of the plant. Molecular methods are used for the diagnosis of the disease, which are laborious, time-consuming and costly, in addition to not allowing rapid detection in the field. In relation to this problem, the method of starch-iodine reaction (RAI) was proposed as a cheap alternative for the diagnosis of HLB by various authors, however, the method has not been widely used, possibly due to lack of diffusion. In the present work the efficacy of the RAI diagnostic method was demonstrated, by comparison with the molecular method of Amplification by recombinase and polymerase (ARP); a molecular method that allows the detection of HLB in the field, but with higher cost. A total of 825 leaf samples were taken from 33 sweet orange (Citrus sinensis L.) plants from orchards of the Department of Caazapá, Paraguay. The samples were analyzed by RAI method, staining and intensity of coloration were observed by optical microscopy. Among these, 33 samples were selected with positive and negative reactions to be analyzed by the ARP method. Results revealed a correlation of 93.6% between both methods. The RAI method, in addition to differentiating HLB symptoms from other diseases and nutritional deficiencies in the plant, is a simple, fast, effective, and economical method for diagnosis if the disease.
| Main Authors: | , , , |
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| Format: | Digital revista |
| Language: | spa |
| Published: |
Facultad de Ciencias Agrarias de la Universidad Nacional de Asunción
2020
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| Online Access: | https://www.agr.una.py/revista/index.php/ria/article/view/586 |
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| Summary: | Huanglongbing (HLB) is one of the most important citrus diseases worldwide. A field level diagnosis is difficult when it is based on visual symptoms, since they can be confused with similar symptoms of other diseases or nutritional deficiencies of the plant. Molecular methods are used for the diagnosis of the disease, which are laborious, time-consuming and costly, in addition to not allowing rapid detection in the field. In relation to this problem, the method of starch-iodine reaction (RAI) was proposed as a cheap alternative for the diagnosis of HLB by various authors, however, the method has not been widely used, possibly due to lack of diffusion. In the present work the efficacy of the RAI diagnostic method was demonstrated, by comparison with the molecular method of Amplification by recombinase and polymerase (ARP); a molecular method that allows the detection of HLB in the field, but with higher cost. A total of 825 leaf samples were taken from 33 sweet orange (Citrus sinensis L.) plants from orchards of the Department of Caazapá, Paraguay. The samples were analyzed by RAI method, staining and intensity of coloration were observed by optical microscopy. Among these, 33 samples were selected with positive and negative reactions to be analyzed by the ARP method. Results revealed a correlation of 93.6% between both methods. The RAI method, in addition to differentiating HLB symptoms from other diseases and nutritional deficiencies in the plant, is a simple, fast, effective, and economical method for diagnosis if the disease. |
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