Detection of Candidatus Liberibacter asiaticus in the relatively new area of citrus plantation (Citrus spp.) in the absent of insect vector Diaphorina citri Kuw in Taro Village, Gianyar, Bali, Indonesia

Abstract

Six species of citrus plants visually observe at citrus plantations in Taro Village, Gianyar, Bali, Indonesia. The village is relatively new area for citrus that was previously reported free from citrus disease, citrus vein phloem degeneration (CVPD) or citrus greening or huanglongbing that caused by Candidatus Liberibacter asiaticus. The six citrus plants were Citrus nobilis, C. amblycarpa, C. reticulata, C. aurantifolia, C. limon and C. maxima. Six species of citrus plants found in the area which showed the CVPD like symptom. Samples from these six citrus species were then analyzed by using polymerase chain reaction (PCR) using 16S rDNA fragments as primers (O11 and O12c) to identify the bacteria, L. asiaticus. The result of this study showed that five of six citrus plants in Taro village were positively infected by L. asiaticus. While one species, C. limon, was negatively infected, the result suggested that C. limon may infected by other organisms or caused by other factors. In addition, we did not found any Diaphorina citri Kuw. in the citrus plantation. This result indicated that the citrus plants in Taro village infected by CVPD disease and the disease spread was by seedling which were made through occulation and brought from other area that has been infected by the disease.