Diversity, distribution, and risk assessment of Banana bunchy top virus (BBTV) infecting abaca from Caraga Region, Philippines

Abaca production has been continuously challenged by several factors, including viral diseases such as abaca mosaic, bract mosaic, and bunchy top diseases. Among diseases, the bunchy top disease hardest hits the production. To address this problem, appropriate and effective strategies for the management and control of these diseases are deemed necessary. Hence, the research is designed to assess the areas in the Caraga Region using spatial distribution modeling tools and molecular diagnosis to detect these virus diseases. Additionally, phylogenetic analysis and pairwise nucleotide identity analyses were also performed. The surveys were carried out in the Caraga Region, namely Agusan del Norte, Agusan del Sur, Surigao del Norte, Surigao del Sur, and Dinagat Islands. At least five municipalities in every province were selected. The occurrence of bunchy top disease was recorded, and collected samples were assessed through visual examination of typical symptoms and confirmed through molecular detection. Results showed that BBTV is present in all Caraga provinces, where a total of 781 samples were collected. A subset (n=503) was tested for BBTV using PCR tests where 25% of the samples were positive. Pairwise nucleotide identity analyses revealed that the BBTV isolates from the current study, collected across Caraga, have a nucleotide identity ranging from 91% to 98% with other global BBTV isolates (n=519). Moreover, the Caraga BBTV isolates were found to form a distinct clade (with 87% bootstrap support) along with other Southeast Asian isolates (n=178), predominantly from Indonesia. This suggests a closer genetic relationship between the Caraga BBTV isolates and BBTV isolates from Southeast Asia, supporting the earlier observation from the phylogenetic tree. Overall, authors contributed novel information on the distribution and diversity of BBTV. By using predictive analyses, the understanding of the epidemiology of abaca bunchy top disease in a major growing region of the Philippines was advanced.