INDUCTION OF PUTATIVE RESISTANT LINES OF ABACA (MUSA TEXTILIS NEE) TO BANANA BUNCHY TOP VIRUS AND BANANA BRACT MOSAIC VIRUS THROUGH IN VITRO MUTAGENESIS

Gamma rays using Cobalt 60 ( 60 Co) irradiation method was conducted to determine the sensitivity doses and response of in vitro propagated abaca to Banana bunchy top(BBT) and Banana bract mosaic (BBrM) diseases. Abaca cultivars (cvs) Tinawagan Pula (TP) and Tangongon (TG) were studied. Both cvs. had similar biological/physiological reactions to gamma rays resulting to high mortality and low shoot proliferation at higher dosage. The LD 30 for shoot proliferation was established at 10 to 15 Gy. Cultivar response (shoot growth per sub -culture cycle) on post-irradiation showed that cv. TG had higher tolerance to gamma ray than cv. TP. A total of 3,210 and 3,765 irradiated abaca including the non -irradiated control were aphid - and mechanically-inoculated with Banana bunchy top virus (BBTV) and Banana bract mosaic virus (BBrMV), respectively. Three months after inoculation, the initial PCR -based diagnosis on putative resistant (PR) materials showed 43 TP (0.6%) and 9 TG (0.9%) selected abaca lines were consistently found negative to BBTV and 36 TP (1.6%) and 15 TG (0.9%) were initially uninfected with BBrMV. Although field trial of these lines and yield components are necessary for final selection, this study showed the bench mark and possibility of mutation breeding to produce virus resistant abaca. As gamma irradiation dose (LD30) coupled with in vitro propagation was established in abaca, screening and gene rating PR lines against viruses infecting abaca can be easily achieved over the conventional breeding works.