Two reciprocal translocations in the burmannica group of M. acuminata

Banana cultivars are derived from hybridizations involving Musa acuminata subspecies. It divided into half a dozen or so subspecies. The current thought on domestication is that it was taken by human settlers when they moved, and interbred with local subspecies. The farmers would then select the least seedy bananas, and propagate them clonally. The modern banana is the result of hundreds, or even thousands, of years of careful selection and management.

Bananas
Image: Canva.

This clonal farming means that understanding genetic variation between banana cultivars is important. Cultivars could be susceptible to extinction from disease. Ideally, you would cross-breed cultivars, so you can breed in resistance, without losing the traits you want from a commercial banana. However, observation of chromosome pairing irregularities in meiosis of hybrids between these subspecies suggested the presence of large chromosomal structural variations. Dupouy and colleagues set out to characterize these rearrangements.

The authors identified two reciprocal translocations in the M. a. ssp. burmannicoides accession ‘Calcutta 4’ compared to the reference genome sequence. This is of interest as ‘Calcutta 4’ shows resistance to various pests and diseases such as nematodes or black leaf streak disease. Characterizing the impact of the two translocations that Dupouy and colleagues describe, on chromosome segregation will be essential to breeding strategies. With this information, it will be possible to enhance the use of the disease resistance-rich burmannica genetic group in breeding programs.