Presence of the integrated endogenous banana streak virus (eBSV) in the B genome of plantain (AAB) is a major challenge for breeding and dissemination of hybrids. As the eBSV activates into infectious viral particles under stress, the progenitor Musa balbisiana and its derivants, having at least one B genome, cannot be used as parents for crop improvement. Here, we report a strategy to inactivate the eBSV by editing the virus sequences. The regenerated genome-edited events of Gonja Manjaya showed mutations in the targeted sites with the potential to prevent proper transcription or/and translational into functional viral proteins. Seventy-five percent of the edited events remained asymptomatic in comparison to the non-edited control plants under water stress conditions, confirming inactivation of eBSV into infectious viral particles. This study paves the way for the improvement of B genome germplasm and its use in breeding programs to produce hybrids that can be globally disseminated.

Banana (Musa spp.) is an important staple food crop and a source of income for resource‐poor farmers in more than 136 tropical and sub‐tropical countries with an annual production of 155 million tons (FAOSTAT, 2018). Many diseases severely constrain banana production, particularly where many pathogens co‐exist (Tripathi et al., 2020). Banana Xanthomonas wilt (BXW) caused by Xanthomonas campestris pv. musacearum (Xcm) is considered among the most destructive banana diseases in East and Central Africa (Tripathi et al., 2009). All the cultivated banana varieties are susceptible, and only the wild‐type progenitor, Musa balbisiana, is resistant to BXW disease (Tripathi et al., 2019). Overall economic losses from BXW were estimated at US$ 2‐8 billion over a decade. The use of disease‐resistant varieties is one of the most effective strategies to manage diseases. Recent advances in CRISPR/Cas‐based genome‐editing can accelerate banana improvement. The availability of reference genome‐sequences and the CRISPR/Cas9‐editing system has made it possible to develop disease‐resistant banana by precisely editing the endogenous genes (Ntui et al., 2020).

Summary: Banana Xanthomonas wilt (BXW), caused by the bacterium Xanthomonas campestris pv. musacearum (Xcm), is the most devastating disease of banana in east and central Africa. The spread of BXW threatens the livelihood of millions of African farmers who depend on banana for food security and income. There are no commercial chemicals, biocontrol agents or resistant cultivars available to control BXW. Here, we take advantage of the robust resistance conferred by the rice pattern‐recognition receptor (PRR), XA21, to the rice pathogen Xanthomonas oryzae pv. oryzae (Xoo). We identified a set of genes required for activation of Xa21‐mediated immunity (rax) that were conserved in both Xoo and Xcm. Based on the conservation, we hypothesized that intergeneric transfer of Xa21 would confer resistance to Xcm. We evaluated 25 transgenic lines of the banana cultivar ‘Gonja manjaya’ (AAB) using a rapid bioassay and 12 transgenic lines in the glasshouse for resistance against Xcm. About 50% of the transgenic lines showed complete resistance to Xcm in both assays. In contrast, all of the nontransgenic control plants showed severe symptoms that progressed to complete wilting. These results indicate that the constitutive expression of the rice Xa21 gene in banana results in enhanced resistance against Xcm. Furthermore, this work demonstrates the feasibility of PRR gene transfer between monocotyledonous species and provides a valuable new tool for controlling the BXW pandemic of banana, a staple food for 100 million people in east Africa.

Banana is a major staple food crop feeding more than 500 million people in tropical and subtropical countries. Its production is largely constrained by diseases and pests in addition to other factors such as declining soil fertility, narrow genetic diversity in germplasm, and inadequate availability of clean planting material. The impact of climate change, particularly a rise in temperature and drought, is predicted to affect production adversely due to direct effect on plant agronomy and also influence on pathogens, pests, and their interactions with host plants. There is need to develop climate‐smart varieties of banana with multiple and durable resistance to combat abiotic stresses such as extreme temperature and drought, and biotic stresses such as pathogens and pests. Modern breeding tools, including genetic modification and genome editing, can be applied for the improvement of banana bypassing the natural bottlenecks of traditional breeding. Intensive efforts using genetic modification have been made to develop improved banana varieties with resistance to biotic stresses; however, these need to be coupled with tolerance to abiotic stresses. Genome editing, an emerging powerful tool, can be applied for developing sustainable solutions to adapt to climate change by resisting biotic and abiotic stresses. CRISPR/Cas9‐based genome editing has been lately established for banana, paving the way for functional genomics allowing identification of genes associated with stress‐tolerant traits, which could be used for the improvement of banana for adaptation to a changing climate. This article presents an overview of recent advancements and prospective on the application of genetic modification and genome editing for developing climate‐smart banana.