Are Bananas Going Extinct?

Kristin Osika

BACKGROUND: Bananas are the United States’ most consumed fruit, totaling more than that of apples and oranges combined. Nonetheless, most people are unaware of the banana’s tumultuous history. The Gros Michel Banana was the world’s leading banana cultivar during the 19th and early 20th century, until a plant disease caused by strains of a soil fungus called Fusarium oxysporum f. sp.cubense (Foc), or the Panama Disease, nearly eradicated the crop in the 1950s. Thus, farmers replaced the Gros Michel with the Cavendish cultivar; a less nutritious, less sweet, and less hardy variety. Despite this, the Cavdendish was the only resistant cultivar farmers could turn to.

Screen Shot 2016-03-06 at 10.18.52 PMTHE PROBLEM: However, a variant of the fungus called Foc Tropical Race 4, or Foc TR-4, has been detected in Jordan, Mozambique, and parts of Asia. The Cavendish is extremely vulnerable to the pathogen due to its lack of genetic diversity. Because the Cavendish is a clone and each crop is genetically identical, if Foc TR-4 can infect one Cavendish, it can potentially contaminate them all.

Foc TR-4 infects the soil, blocking a plant’s ability to take in nutrients and also creates spores, which spread to infect other plants. The pathogen is also extremely hard to contain. Although Foc strains spread slowly, they are almost impossible to eliminate from the soil. Moreover, the Foc TR-4 can stick to boots and gloves. A single clump of dirt lodged in the tread of your shoe could carry the disease to a new plantation. Worse, the pathogen could produce “resting spores” which could lie dormant in the soil for decades. Destroying a single crop is not enough. Foc TR-4 could eradicate the cavendish and threaten national food security.

THE SOLUTION: The most basic method to stop Foc TR-4’s spread is through good farm hygiene and prompt quarantine and destruction of infected plants. Also, the Cavendish industry now produces crops from tissue-culture, thereby creating pathogen-free plantlets. Finally, farmers are trying to increase genetic diversity and genetically engineer crops to become more resistant. However, Gen Kema, a fusarium researcher at Wangeningen University, believes future spread is inevitable, saying, “I’m incredibly concerned. I will not be surprised if [Foc TR-4] pops up in Latin America in the near future.” If the disease takes root in Latin America, where 80% of the Cavendish industry resides, the world may have to turn to another banana variety and say good-bye to the Cavendish.

Josh Metzger ’17

 

References

Worse comes to worst: Bananas and panama disease—when plant and pathogen clones meet. (2015).

PLOS. http://dx.doi.org/10.1371/journal.ppat.1005197

Butler, D. (2013). Fungus threatens top banana. Nature. http://dx.doi.org/10.1038/504195a

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