Evaluation of 20 enset (Ensete ventricosum) landraces for response to Xanthomonas vasicola pv. musacearum infection

Abstract

Bacterial wilt, caused by Xanthomonas vasicola pv. musacearum (Xvm), formerly X. campestris pv. musacearum, is the most threatening and economically important disease of enset (Ensete ventricosum), the multipurpose food security crop orphan to south and southwestern Ethiopia. Xvm has also had a major impact on banana and plantain production in East Africa following its detection in Uganda in 2001 and subsequent spread. Effective control of this disease currently relies on integrated disease management (IDM) strategies including minimization of field pathogen inoculum and deployment of wilt resistant enset landraces. Identifying landraces with stable and durable Xvm resistance will greatly accelerate breeding of varieties that can be included as a component of IDM. In this study, 20 enset landraces previously reported to exhibit lower susceptibility to Xvm were grown in pots under open field conditions and inoculated with an aggressive Xvm inoculum isolated from a disease hotspot area. Longitudinal and survival analyses were applied to each landrace, based on disease units representing a combination of area-under-disease progress stairs, disease index and apparent infection rate. Considerable variation was observed among the 20 landraces; however, none exhibited full immunity to Xvm infection. Three landraces, viz. Hae’la, Mazia and Lemat (HML), showed lowest susceptibility to Xvm as evidenced by lower disease units and higher survival rates. Landraces Kuro, Gezewet, Bededet, and Alagena showed similar levels of Xvm infection as did HML, but with lower survival rates. By contrast, landrace Arkia showed the highest infection level and lowest survival rate, suggesting a high degree of susceptibility to Xvm. This study identifies new material that can be used in future breeding programmes to develop Xvm-resistant enset varieties.

The pangenome of banana highlights differences between genera and genomes

“…For example, three landraces of Ensete among 20 studied were found to be resistant to Xanthomonas vasicola pv. musacearum (Muzemil et al, 2019). A similar study from 72 diverse Musa cultivars identified several resistant genotypes, mostly with BB or hybrid AB genome types (Nakato et al, 2019).…”

The Ethiopian staple food crop enset (Ensete ventricosum) assessed for the first time for resistance against the root-lesion nematode Pratylenchus goodeyi

“…musacearum), whilst 'Gefetanuwa', which supported the highest reproduction of P. goodeyi, also supports rapid X. vasicola pv. musacearum development, as does 'Arkiya', which has been used as a susceptible control in evaluation studies (Muzemil et al, 2019). Although 'Arkiya' was regarded as one of the cultivars with higher densities of P. goodeyi in a previous survey (Bogale et al, 2004), the P f and RF were similar to the other two cultivars ('Maziya' and 'Heila').…”

Maintenance and expansion of genetic and trait variation following domestication in a clonal crop

“…This suggests a predominantly genetic (rather than agronomic or environmental) basis to farmer-selected attributes and enables initial future characterization of poorly known landraces based on genotype (Borrell et al, 2021). In addition, evidence of a genetic basis for traits such as disease tolerance enable easier comparison of extensive regional Ethiopian literature that has assessed disease response in limited numbers of landraces (Gezahegn & Mekbib, 2016;Haile et al, 2020;Muzemil et al, 2021). This also highlights the challenge of trait analysis using only vernacular information.…”