Plant 119

Musa x paradisiaca L. (Musaceae)



Bananas and plantains are the fourth most important food staple in the world; about 100 million tonnes are consumed annually and more than half a billion people depend on plantains. They are also one of the top ten most-traded agricultural commodities.

Bananas and plantains are tall herbs, native to the Malay-Indonesian region, but now planted throughout the tropics and subtropics. Most cultivated bananas and plantains are derived from complex, ancient crosses between two wild species, Musa acuminata and Musa balbisiana. Fruits, technically berries, of the wild species have seeds but those of cultivated bananas and plantains are seedless. The distinction between bananas and plantains is entirely artificial. Generally, bananas are sweet and eaten raw, whilst plantains are starchy and eaten cooked.

Bananas are late-comers in the relationships of western Europeans with plants. In the wake of Islam, bananas had spread through the Near East and North Africa into the Iberian Peninsula by the ninth century. During the sixteenth century, the Portuguese introduced bananas to the Americas, via West Africa and the Canary Islands but they were novelties in the capitals of western Europe. By 1736, Linnaeus had coaxed a banana plant to flower in the glasshouses of George Clifford; the first banana to flower in Europe. Before bananas could become commonplace in western markets it was necessary to have rapid transport systems and mechanisms to slow ripening.

There are thousands of banana cultivars; naturally occurring mutants selected for vigour, yield, hardiness, fruit quality and, importantly, seedlessness. Since banana cultivars are seedless they cannot reproduce without human help, so once in cultivation they must be multiplied by vegetative propagation. Evidence from Papua New Guinea indicates banana cultivation may be up to 10,000 years old. Despite all the cultivars grown, only two nineteenth-century cultivars have found favour in international trade, the thick-skinned 'Gros Michel' and 'Cavandish'. The paucity of useful cultivars, combined with vegetative propagation, makes commercial banana production particularly vulnerable to disease outbreaks. Since the 1950s, commercial production of 'Gros Michel' has been uneconomic because of Panama disease.

Today, subsistence and commercial production of 'Cavandish' bananas is threatened by a new strain of Panama disease. Other than prevention, cultivar replacement is the only viable option to maintain productivity. The future of bananas is supermarkets may be less bleak than imagined; within bananas as a whole there is plenty of fungal resistance, the trick is to get this resistance into commercial bananas.

Further reading

Marin DH et al. 2003. Black sigatoka: an increasing threat to banana cultivation. Plant Disease 87: 208-222.

Robert S et al. 2012. Contrasting introduction scenarios among continents in the worldwide invasion of the banana fungal pathogen Mycosphaerella fijiensis. Molecular Ecology 21: 1098-1114.

Simmonds NW & Shepherd K 1955. Taxonomy and origins of cultivated bananas. Botanical Journal of the Linnean Society 55: 302-312.

Stephen Harris