A RUBY Reporter for Efficient Banana Transformation and Development of Betalain-Rich Musa Germplasm

Bananas are economically important crops valued for both their nutritional and dietary uses. However, the global banana industry suffers from a narrow base dominated by a single variety. Developing novel varieties enriched in health-promoting compounds such as betalains can help diversify banana germplasm and meet evolving consumer demands. In this study, the RUBY reporter system was employed to produce betalain-rich bananas via stable and transient genetic transformations. Transient transformation by injecting 3 mL of Agrobacterium suspension into immature fruits produced vivid red-purple pulp containing up to 1.78 mg/g of betalains. For stable transformation, embryonic cell suspensions expressing RUBY exhibited a red-purple coloration after the first screening, reducing the selection period from 45 to 15 days. These findings demonstrate that RUBY is a reliable visual reporter for efficient screening and can be used to develop nutritionally enhanced bananas.