Can genome sequencing save bananas from the brink of death?
Smoothies of the future may be vastly different from the ones of today. A prominent ingredient — the banana — is in grave danger of getting wiped out by a triple fungal threat known as the Sigatoka disease complex.
Yellow sigatoka, eumusae leaf spot, and black sigatoka have been devastating plantations worldwide over the past century. All three fungal pathogens target the Cavendish banana, which is the most common variety. Black Sigatoka has been singled out as the most lethal pathogen of the bunch, leading to crop losses of around 50 percent and early ripening, which causes the fruit to rot before reaching its customers.
Though there are clear implications for smoothie lovers, the effects of a banana shortage would most severely impact countries that rely on bananas as a staple food.
According to University of California Davis molecular plant pathologist Ioannis Stergiopoulos, the entire banana industry could disappear in 5-10 years from fast-acting fungal diseases, such as the Sigatoka complex. For this reason, Stergiopoulos and a team of plant scientists decided to peel back the pathogens’ genomes to probe for solutions.
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The researchers found that the two most threatening pathogens — eumusae leaf spot and black Sigatoka — don’t simply shut down the banana plant’s immune system, as previously thought. They have also undergone changes in their metabolisms that parallel those of the host plant, which allow the pathogens to efficiently steal the banana’s nutrients.
Understanding the genomic basis of the pathogens’ threat to bananas will hopefully lead to environmentally friendly methods of protection — the enormous amount of fungicide that is currently sprayed on these plants poses a threat to plantation workers and nearby communities, and has led to increasingly resistant fungi.
Scientists may also use the new genomic information to fundamentally alter the banana plant — one that is suitable for mass production and export, but is also resistant to Sigatoka.
The findings were published in two papers in PLOS Genetics:
Rafael E. Arango Isaza, Caucasella Diaz-Trujillo, Braham Dhillon, Andrea Aerts, Jean Carlier, Charles F. Crane, Tristan V. de Jong, Ineke de Vries, Robert Dietrich, Andrew D. Farmer, Claudia Fortes Fereira, Suzana Garcia, Mauricio Guzman, Richard C. Hamelin, Erika A. Lindquist, Rahim Mehrabi, Olman Quiros, Jeremy Schmutz, Harris Shapiro, Elizabeth Reynolds, Gabriel Scalliet, Manoel Souza, Ioannis Stergiopoulos, Theo A. J. Van der Lee, Pierre J. G. M. De Wit, Marie-Françoise Zapater, Lute-Harm Zwiers, Igor V. Grigoriev, Stephen B. Goodwin, Gert H. J. Kema.Combating a Global Threat to a Clonal Crop: Banana Black Sigatoka Pathogen Pseudocercospora fijiensis (Synonym Mycosphaerella fijiensis) Genomes Reveal Clues for Disease Control. PLOS Genetics, 2016; 12 (8): e1005876 DOI: 10.1371/journal.pgen.1005876
Ti-Cheng Chang, Anthony Salvucci, Pedro W. Crous, Ioannis Stergiopoulos. Comparative Genomics of the Sigatoka Disease Complex on Banana Suggests a Link between Parallel Evolutionary Changes in Pseudocercospora fijiensis and Pseudocercospora eumusae and Increased Virulence on the Banana Host. PLOS Genetics, 2016; 12 (8): e1005904 DOI: 10.1371/journal.pgen.1005904
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