Moleculardetection and Evaluation Ofresistance of Abaca Hybrid (BC2) to Bunchy Top Vtruses in Eastern Visayas Region of Philippines

Abaca (Musa textilis Nee) is an important fiber crop in the Philippines. The infection of Abaca Bunchy Top Virus (ABTV) causes major economic losses on the abaca plantation in the Eastern Visayas region. Abaca hybrid (BC2) was developed by Institute of Plant Breeding-University of the Philippines Los Banos (IPB-UPLB) to manage the ABTV that is prevalent all over the archipelago of Philippines. The reaction of BC2 to bunchy top viruses (BTVs) in Eastern Visayas was tested and the virus transmission efficiency was evaluated. Leyte isolate infected 100% of Inosa plants, Samar (93.3%), Biliran (90%) and Southern Leyte (80%) based on symptoms of the disease. In PCR, 100% infection was recorded in Inosa but no disease symptoms were expressed on Pacol and BC2 due to BTV. Based on disease reaction, BC2 and Pacol were highly resistant to the BTVs, while Inosa was highly susceptible. Bunchy top disease symptoms were evident 26 days after incubation (DAI) by Leyte isolate, S. Leyte (30 DAI), Biliran (32 DAI) and Samar (38 DAI). No symptoms were observed with Pacol and BC2. In Inosa, BTV isolates from Leyte and S. Leyte were detectable at 5 DAI, Samar (6 DAI) and Biliran isolate (7 DAI) using PCR with the primers BBT1 and BBT2 at -349 bp. The study confirms BC2 and Pacol as highly resistant to all isolates of BTVs in Eastern Visayas.