Researchers know that to cause plant diseases, pathogenic microorganisms secrete proteins, called effector proteins, into the host plant's tissue, Valent said. The proteins suppress the plant's immunity and support the pathogen's growth. The goal of the study was to learn if fungi need different secretory systems to aid their invasion into host plants.
"We knew that over time bacterial pathogens evolved multiple secretion systems to target effector proteins where they need to go. We didn't know whether fungi, which cause the major diseases in most crop plants, also require different secretory mechanisms," she said.
They learned that the rice blast fungus Magnaporthe oryzae has evolved a novel secretion system for effectors that go inside the plant cell. In contrast, effectors that end up in the space outside the plant cells are secreted by a classical system, which is shared by organisms from fungi to humans.
"In this study, we focused on investigating how the fungus secretes effectors during invasion of rice tissue by producing strains secreting effectors linked to fluorescent proteins from jellyfish and corals. We performed microscopy to watch the fungus secreting these fluorescent proteins as it grows inside rice cells, and we noticed that normal treatments that block protein secretion didn't stop those effectors that end up inside rice cells," Valent said.
"Identifying how these processes function will help us understand how disease microorganisms evolve and prove pivotal in controlling blast diseases," she said.
|Contact: Barbara Valent|
Kansas State University