What is loved about bananas is that you can just peel it and it’s ready to eat. Bananas are not only nutritious but also popular in smoothies, milkshakes, banana splits, cakes and more. However, no one can predict that the same bananas we know now will exist forever. In the 1950s, the banana cultivar Gros Michel aka Big Mike was menaced by the microscopic fungus, Fusarium oxysporum f. sp. cubense, the causative agent of Panama disease. Another cultivar, Cavendish, resistant to Panama disease, replaced Gros Michel. Bananas have been attacked by other diseases such as Yellow Sigatoka and Black Sigatoka which are caused by the fungi Mycosphaerella musicola and Mycosphaerella fijiensis respectively.
If an aggressive fungal pathogen appears, an outbreak of this fungal disease can wipe out the host plants, especially if they are genetically homogenous. The genetically identical plants are very vulnerable because only one clone of the fungus is enough to kill all the banana plants. It is the exact problem faced by the late Gros Michel cultivar and now, also, of the Cavendish cultivar. Every single Cavendish banana plant in the world is genetically identical as they are clones. This is very dangerous for the survival of this cultivar.
And, as could have been predicted, a new strain of the Panama disease emerged around 1990: the Tropical Race Four (TRF) which can also cause Panama disease in the Cavendish cultivar. According to data from FAO, what it is especially alarming is that Black Sigatoka and TRF were able to reduce the world production of bananas by 3.8 % in 2012 compared to 2011.
The solution that some researchers have is the genetic modification of banana plants in order to resist such diseases. Researchers from Belgium produced a transgenic banana integrated with two rice chitinase genes to give resistance against the Black Sigatoka. They observed a delay in disease development and a decrease in the necrotic leaf area in these transgenic banana lines. Thus, the future survival of bananas could rely on transgenics.
References:
http://pubs.rsc.org/en/content/articlepdf/2003/po/b303002b
http://futureoffood.ox.ac.uk/sites/futureoffood.ox.ac.uk/files/Science2012fungus.pdf
http://spendmatters.com/2014/03/17/black-sigatoka-threatens-world-banana-production-and-prices/
Kovács, Gabriella, László Sági, Géraldine Jacon, Geofrey Arinaitwe, Jean-Pierre Busogoro, Els Thiry, Hannelore Strosse, Rony Swennen, and Serge Remy. “Expression of a rice chitinase gene in transgenic banana (‘Gros Michel’, AAA genome group) confers resistance to black leaf streak disease.”Transgenic research 22, no. 1 (2013): 117-130.
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