Bananas– The war on wilt, Origin of edibility

Bananas– The war on wilt, Origin of edibility; Rody Blom, Saskia Bollerman, Janna Horjus, Koen Rurenga
At the origin of edible bananas are wild species that typically produce fruits full of seeds.
Even though only a handful of species have been domesticated, the banana's wild relatives comprise more than 75 species that are native to the humid tropical forests that extend from India to the Pacific.
We now know that edibility in the bananas and plantains depends primarily on the occurrence of parthenocarpy, which is the development of the fruit without pollination of the female flower (Perrier, 2009, 2011)
and always coupled with more or less female sterility, causing a tendency for the fruit to be seedless (Dodds, 1943).
The potential to produce parthenocarpic fruits has been traced to genes present in Musa acuminata (Simmonds, 1953).
But since these plants were still fertile, they continued mating with other fertile banana plants.
Domestication for edibility most likely started with farmers transplanting the offshoots (suckers) of plants that were edible by virtue of having less seeds and more pulp.
latter could be plants from the same or different (sub)species.
Sterility is most likely due to a combination of structural and genetic factors (Sardos et al. 2016).
The structural factors are linked to hybridization between distant relatives as inherited mismatched chromosomes made it difficult for the progeny to produce fertile ovules and pollen.
But scientists also believe that farmers preferentially propagating the plants that produced fruits with the least seeds might have selected for genes that contribute to sterility (Sardos et al., 2016).
Triploidy made further sexual reproduction extremely unlikely.
Although sterility and parthenocarpy are important factors that contribute to the desirability of banana fruits, sterility has impeded progress in breeding programs.
Through natural somatic (vegetative) mutation, hybridization, and selection over many thousands of years, considerable genetic variability has arisen within the cultivated bananas, giving rise to more than 1000 varieties (Nelson, 2002).
Figure 2. Evolution of the cultivated bananas, modified from Simmonds (1995) by Nayar (2010)