© Oswaldo Rivas / Reuters
Chocolate lovers, brace yourselves. Your favorite sweet treat is at war with a fungus that reproduces by cloning, according to a new study. The fungal disease, which poses a serious threat to cocoa plants, was previously thought to multiply sexually.
It was traditionally believed that the fungus Moniliophthora roreri - which causes frosty rot pot, a disease which has devastated cocoa plantations throughout the Americas - reproduced sexually, because it belongs to a group of fungi that produces mushrooms through sexual means.
However, researchers at Purdue University have determined that the fungus actually generates billions of cocoa pod-destroying spores through cloning - despite having two mating types and seemingly functional mating genes.
"This fungus is phenomenally unusual - it has mating types but doesn't undergo sexual reproduction," Jorge Díaz-Valderrama, doctoral student in mycology, said in a
statement. "This knowledge is biologically and economically valuable as we seek better insights into how mushrooms come about and how we can reduce this disease's damage to the cocoa industry."
Despite possessing two mating types, Díaz-Valderrama and colleague Catherine Aime, an associate professor of mycology, couldn't find any evidence that the two types were combining in the field or the lab. In addition, no record of M. roreri mushrooms exist - a further sign that the fungus is reproducing through cloning.
"Fungi usually start reproducing via cloning when they're very well suited for their environment," Aime said. "In terms of resources, sex is expensive while cloning is a cheap and easy way to produce a lot of offspring."
Interestingly, while both mating types were found in South America, only one type was found in Central America. This finding supports the hypothesis that the fungal disease originated in South America and was more recently introduced into Central America, where it rapidly spread via cloning.
Frosty rot pot has wreaked havoc on cocoa plantations in much of the Americas, dropping cocoa yields by up to 100 percent in some areas, and forcing many farmers to abandon their plantations. Brazil is currently the only cocoa-producing country in the continental Americas to remain untouched by the fungal disease. Much of the world's cocoa production has relocated to West Africa, partly due to the spread of frosty rot pot.But although frosty rot pot remains a very real threat to cocoa plants, chocolate lovers shouldn't panic just yet, according to Díaz-Valderrama.
"We're working on identifying
biochemical components that could be useful for controlling frosty pod rot and protecting vulnerable cacao-growing regions," he said.
But price already skyrocketed, few years back. Cocoa prices went up, and the chocolates were not far behind. This is one reason why different milk chocolates, and strange mixtures are more popular than they used to, similarly unusual sizes (like 90 g bars instead of 100 g ones). They are cheaper to produce now. True chocolates are markedly more expensive than they were 3+ years back.
In 2000 prices were below 1000 USD per tonne, now they are about 3000 USD/t which is close to 3-years high. This level has been stable for the last year, but it is already very high. I wouldn't be surprised if a record from late 70's was beaten.
However, the find that the fungus reproduced by cloning is actually a good thing. Bad thing it can return to sexual reproduction very quickly, but at this stage it is very vulnerable. I doubt they will be able to nail it though, because that would require more cooperation than is usual in this field. I mean not scientists but planters and owners.