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.’

Comparative RNA-seq analysis of resistant and susceptible banana genotypes reveals molecular mechanisms in response to banana bunchy top virus (BBTV) infection

“…Two banana genotypes, wild Musa balbisiana (BBTV-resistant 9 ) and Musa acuminata ‘Lakatan’ (BBTV-susceptible 6 ), were mock- and BBTV-inoculated by Pentalonia nigronervosa and the RNA samples from young leaf tissues were isolated at 72 h post-inoculation (hpi). In total, 12 RNA samples were sent for next-generation sequencing using Illumina NextSeq 500/550 to represent the total transcriptomic profiles of BBTV-free and BBTV-inoculated resistant and susceptible banana genotypes.…”

“…BBTV-resistant wild M. balbisiana 9 (Acc No. MB 13-155) conserved and maintained at the National Plant Genetic Resource Laboratory (NPGRL), Institute of Plant Breeding, University of the Philippines Los Baños (IPB-UPLB) and BBTV-susceptible M. acuminata ‘Lakatan’ 6 were used for the transcriptomic analysis (Fig. 3 ).…”

“…Still, deployment of BBTV-resistant banana varieties in conjunction with a high-throughput, rapid and sensitive BBTV detection system is still the most sustainable approach to attaining optimum banana production. BBTV-resistant ‘Mapilak’ banana cultivar was previously developed through gamma irradiation and in vitro induced mutations of Musa acuminata ‘Lakatan’ 6 . However, the resistance reaction of this cultivar only accounted for 20% of the disease incidence reduction 7 .…”

Using Mutation Breeding to Improve the Eating Characteristics of the Fusarium Wilt-Resistant Banana Variety, ‘Goldfinger’ (AAAB)

“…Previous mutation work in Musa spp. has focused on improving agronomic character-istics, like plant height [42,43] and yield [5,44,45], and the disease resistance [46,47] of commercially relevant varieties. While these outcomes were not the primary focus of the present study, the phenotypic variation observed in the initial field planting of 631 variants (Phase II) demonstrates the 35 Gy irradiation treatment was effective in generating a population of Goldfinger mutant lines from which such improved agronomic selections could be made.…”

Biology of Pentalonia nigronervosa and Its Efficiency as a Vector of Banana Bunchy Top Virus After Being Bred in Rat Taro (Typhonium flagelliforme)

“…The virus circulates within the body of the tick but does not replicate within its vector body nor is there any transovarial transmission (Watanabe & Bressan 2013b). To be an infective viral vector, P. nigronervosa must obtain hosts or plants affected by banana stunting virus for at least 4 hours, but most of these leaf ticks must skip the feeding period of up to 18 hours (Damasco et al, 2020). Once the tick has become infective, this vector can maintain its infectiveness for a period of time from 15 -20 days, it can even be up to its entire life (Rahayuniati et al, 2021a).…”