Gamma Radiation and In Vitro Induced Banana Bunchy Top Virus (BBTV) Resistant Mutant Lines of Banana cv ‘Lakatan’ (Musa sp., AA)

Abstract

Gamma irradiation coupled with in vitro technology was used to develop BBTV resistance in banana cv ‘Lakatan.’ Ten (10) resistant lines were selected after several generations of evaluation and selection. The selected lines (M1V3–M1V4) showed low disease incidence in the field under high disease pressure and, likewise, low disease incidence with aphid inoculation of the virus. Further disease evaluation (M1V4–M1V5) on these lines consistently showed low BBTV disease incidence (11.62–28.57%) 30 mo from planting (MAP). The genetic variability in morpho-agronomic traits derived from SHAN cluster analysis grouped the selected lines into four major clusters for qualitative traits at 0.636 coefficient of similarity and three clusters for quantitative traits at 0.11 Euclidian distance coefficient. Selections based on agronomic traits showed significantly earlier flowering in three mutant lines and shorter stature in two mutant lines. Short strand repeat (SSR) analysis using 11 primers detected a high level of polymorphism in mutant lines. Mutant lines were differentiated from the ‘Lakatan’ control by the absence of one or few alleles in mutant lines with four primers and/or addition of one or few alleles in mutant lines with two primers. SSR analysis revealed genetic differences among mutant lines and between mutant lines and ‘Lakatan' control. The results of the study further affirmed stable BBTV resistance in advanced generation evaluation (M1V4M1V5). Five out of ten resistant lines were selected for further evaluation in multi-location field trials as a requirement for registration and release of new BBTV resistant mutant variety of ‘Lakatan.’