Scientists Seek Cure for Witches' Broom Disease Which Kills Chocolate Trees

Posted on November 3, 2014

Witches Broom disease on a chocolate tree

A devastating disease called Witches' Broom disease is continuing to kill chocolate trees. Scientists are seeking a cure for the disease which is caused by a fungus named Moniliophthora perniciosa. The disease destroyed 70% of Brazil's chocolate trees in the late 1980s and 1990s resulting in an economic disaster for the country.

The above image shows the mushroom stage of Witches' Broom disease. The mushrooms resemble fairytale-like pink mushrooms. The mushrooms are enchanting but are filled with millions of spores that cause damage to chocolate trees when released. The spores enter the trees through surface wounds and tree gaps called stomata. The trees grow green outgrowths that give the disease its name. The outgrowths are described by the researchers as "bizarre green outgrowths" that resemble brooms. These brooms turn brown about three months after a tree is infected. More spore containing mushrooms emerge from these brown growths and the chocolate tree killing process continues.

Scientists led by Gonçalo Pereira of the Universidade Estadual de Campinas in Brazil have started the Witches' Broom Genome Project in an effort to learn more about the disease so it can be eradicated. The researchers are using a dual RNA-seq analysis to monitor the interaction between the fungus and the chocolate tree. An article will published in The Plant Cell next week that describes their research and the data they have discovered so far.

Paulo Teixeira, the author of the study, says in a statement, "Knowing the molecular and physiological basis of a disease is an important step towards developing effective control strategies."

A team led by Brazilian scientist Goncalo Pereira created the Witches' Broom Disease Transcriptome Atlas to help researchers share information about the disease. So far scientists have identified 433 fungal genes that are considered "particularly active" in the green fungus brooms.

Photo: Goncalo A.G. Pereira