Blueberries face a scourge. Like many crops, they are under constant attack from fungal infections, which endanger crops, increase costs and labor, and threaten food security. In the case of blueberries, a deceptive enemy is Mummy Berry disease. Caused by the fungus Monilinia vaccinii-corymbosi, or Mvc, it attacks both wild and cultivated blueberries, with crop losses of up to 80%, according to the American Society for Plant Pathology.

Mummy berry disease can cause a lot of damage in the United States, the world's largest producer of the fruit. In 2019, US farmers grew more than 670 million pounds of blueberries, with a total crop value exceeding $900 million, according to the US Department of Agriculture. Blueberries will grow thanks to this humble berry's reputation as an antioxidant-rich "superfood."

Mvc employs mimicry and subterfuge in his assault. The fungus triggers two phases of blight on blueberry plants, all while evading the host's defenses. Blight first degrades shoots, leaves, and young shoots. The fungus then mimics a pollen tube to colonize mature flowers. Once enthroned, Mvc consumes the developing berries from within, transforming them into wrinkled, pale, fungus-filled "mummified" husks that fall to the ground, release spores, and start the cycle all over again.

Phase Genomics partnered with a team from North Carolina State University and the University of Florida, using Hi-C proximity ligation technology to sequence and assemble the complete Mvc genome. Recently published, this montage is already showing us how the fungus achieves the duplicity and kneecaps of the blueberry's defenses. For example, certain Mvc genes could stop the production of salicylate, one of the anti-pathogenic defenses of the blueberry plant. Other Mvc genes produce factors to degrade host tissues, so the fungus can settle inside freshly mummified berries.

Information gleaned from the Mvc genome could reveal targets for specific new antifungal treatments and other interventions to save ruined berry plants. They are also raising new questions for the Mummy Berry research. For example, Mvc strains may employ different mating strategies, based on variations in the location of the type of mating that we discovered between the reference isolate and a second strain. Additionally, the Mvc genome likely holds more secrets about its remarkable mimicry, such as how it tricks pollinators into thinking diseased tissues are flowers during the early blight phase, a hoax that helps spread spores to blueberry blossoms. ripe for the second blight.

"By studying the genetic underpinnings of the life cycle and virulence of Mvc, its development, mating strategies, and host adaptations, we gain the kind of foundational knowledge needed to develop and implement sustainable disease management solutions," said lead author. , Dr. Hamid Ashrafi, assistant professor at North Carolina State University.

Mvc's close relatives include dozens of species that infect other berries, as well as stone fruits and pips. Only time will tell which of the secrets we are learning about Mvc apply to these pathogens. But these efforts illustrate how powerful genomic methods like Hi-C proximity ligation produce high-quality genomes that open the curtain on the deadly theatricality of these pathogens, giving crops an edge.