Most are unaware of it but the evolutionary arms race between plants and plant diseases is always happening around us. Fungi are a major cause of plant diseases and are responsible for large-scale harvest failure in crops like maize and other cereals all over the world.
Researchers analyzed the genetic make-up of Sporisorium reilianum, an important maize parasite. Based on a comparison with the genome of a related fungal species, they succeeded in identifying new genes in maize infestation.
The smut fungi Ustilago maydis and Sporisorium reilianum are parasites that attack maize plants. Ustilago maydis causes a disease known as boil smut or common smut, which is characterized by large tumor-like structures on the leaves, cobs and male flowers in which the fungus proliferates and produces spores. Sporisorium reilianum also attacks maize plants; however, it infects the entire plant and its symptoms become manifested only in the male and female flowers. For this reason, it is also referred to as 'maize head smut'.
Little has been known up to now as to how these pathogens cause disease. Four years ago, a team of scientists succeeded in decoding the genome sequence of Ustilago maydis. They demonstrated that the genes, for a large number of completely new proteins secreted by the fungus, are arranged in groups on the chromosomes in gene clusters. These proteins control the colonization of the host plant.
The researchers were initially only able to demonstrate the presence of these proteins in Ustilago maydis. "However, we found it hard to imagine that these proteins, which play such a crucial role in maize infestation, should only be present in the genome of a single smut fungus. For this reason, we also sequenced the genome of Sporisorium reilianum," explains Regine Kahmann from the Max Planck Institute in Marburg.
Over 90 percent of the proteins secreted by Ustilago maydis also exist in Sporisorium reilianum. However, many of these proteins differ significantly between the two species and are therefore difficult to detect at the gene level. "Surprisingly, however, almost all of the genes of the two organisms are arranged in the same order. As a result, we were able to superimpose the two genomes like blueprints and display the differences in this way," says Kahmann.
The scientists discovered 43 divergence regions, in which the differences in the two sets of genes are particularly significant. These included all of the gene clusters identified four years ago, whose genes play an important role in the infection of the host plant. In addition to this, four out of six randomly selected divergence regions influence the strength of Ustilago maydis infection, and surprisingly, one of these does not contain genes for secreted proteins. "This shows that additional, thus far undiscovered molecules control the relationship between the fungus and the plant," commented Jan Schirawski from the University of Göttingen.
Evolutionary warfare between maize and fungus
Therefore, the genes that differ most strongly between the two fungi are in all likelihood those that play an important role in the infestation of the maize plant. The different life styles of Ustilago maydis and Sporisorium reilianum presumably resulted in the development of species-specific gene variants in these fungi over the course of evolution, e. g. to suppress the plant's immune response. The maize plants, in turn, modified the target molecules of these fungal proteins. Maize plants apparently form at least one protein to counteract each of the proteins released by the fungi.
"What we see here are the signs of an ongoing struggle between the defending plant and attacking parasite. The variety of the weapons of attack and defence used is the product of an arms race between the plant and the fungus. Each modification on one side is countered by an adaptation on the other," explains Schirawski.
With the help of the molecules they discovered on the basis of the differences between the two fungi, the Marburg-based researchers have the long term hope that it will be possible to develop new strategies for disease control of these and related plant parasites.
- PHYSICAL SCIENCES
- EARTH SCIENCES
- LIFE SCIENCES
- SOCIAL SCIENCES
Subscribe to the newsletter
Stay in touch with the scientific world!
Know Science And Want To Write?
- Statistical Mechanics Reveals The Ideal Hideout During A Zombie Takeover
- Men With Short Index Fingers And Long Ring Fingers Are Nicer To Women
- Big Data Tackles How Urban Movement Is Linked To Social Activity
- What Does Your Gut Microbiome Have To Do With Your Immune System?
- Cruithne: Earth's Other 'Moon' Could Reveal Mysteries Of The Solar System
- The Real Meaning Of The Blue Black White Gold Dress
- Creepy IBM AI toy coming for Christmas—the Continuum paradox. Eerie IBM video link below.
- "I don't want to be too much of a downer, so here is an effort by Mr. Nimoy to shake off the Spock..."
- "The Chinese herb Radix . . . rather incomplete, since that simply means Root (of). A bit of..."
- "My wife showed me this picture on her I-phone and thought I was crazy for saying it was blue. I..."
- "New Science not peer reviewed. Graham Lawton where are your credentials? Who are these scientists..."
- "Very much enjoyed the article.Currently I am abstaining from added sugar due to lack of interest..."
- Zombie outbreak? Statistical mechanics reveals the ideal hideout
- Study challenges theory on unconscious memory system, links hippocampus to unconscious memory
- Saving energy: Increasing oil flow in the keystone pipeline with electric fields
- Experts warn of stem cell underuse as transplants reach 1 million worldwide
- Feast or famine diet could extend longevity