Crop-rotation Resistant Rootworms Have A Lot Going on in Their Guts
News Jun 11, 2015
Previous research from this team, led by University of Illinois eco-physiologist Manfredo Seufferheld, found that heightened activity of protein-degrading enzymes and changes in the microbial community of the gut allowed rotation-resistant rootworm beetles to tolerate a diet of soybean leaves longer than other rootworm beetles. This gave them an advantage wherever crop rotation was practiced: If a female rootworm beetle lingered long enough in a soybean field to deposit her eggs there, and that field was planted with corn the following spring, her larvae would emerge, feed on corn roots and grow up to repeat the cycle. (Any larvae that emerge in soybean fields will die.)
The new study looks at gene expression in the insect’s gut, and also finds significant differences between rotation-resistant and susceptible (also called “wild type”) rootworm beetles. These differences in gene expression may help researchers develop molecular markers to identify rotation-resistant rootworms and improve rootworm-management strategies.
“We found many genes that are differentially expressed between wild-type and rotation-resistant rootworms – over 3,000 genes,” Seufferheld said.
Some of these genes code for proteins involved in immune regulation and antimicrobial functions, he said. This could help explain the differences seen in microbial populations in the digestive systems of rotation-resistant and wild-type rootworms, he said. The same types of microbes are present in each, but in different proportions.
In an earlier study, Seufferheld and his colleagues found that rotation-resistant rootworms had higher activity of a protein known as cathepsin L. This enzyme helps the beetles digest soybean leaves and its increased activity gives rotation-resistant bugs an edge over their wild-type peers. When the researchers treated the bugs with antibiotics, however, the level of cathepsin L activity in the rotation-resistant rootworms dropped to that of the wild-type bugs. This caused the rotation-resistant beetles to die just as quickly as their wild-type peers on a diet of soybean leaves.
“The microbial community is somehow helping the rootworms boost the cathepsin levels,” Seufferheld said. “We don’t know exactly how.
“We also found differentially regulated genes involved in detoxification and genes involved in transport of metabolic products, lipids, sterols and drugs in and out of the cell,” Seufferheld said. Some of these genes are associated with insect resistance to other toxins, he said.
The new study deepens scientists’ understanding of the complex interplay of forces that give rise to rotation resistance, he said.
“The evolution of resistance in insects is complex: Human activity, the evolutionary history of the insects, the host and non-host plants, the microbial community and the genes all play a role,” Seufferheld said.
All of these factors exist within an environmental context, he said. In areas dominated by corn and soybeans, rotation-resistance is more prevalent, while more diverse agricultural landscapes that also include corn and soybeans report no problem with rotation resistance.
“When we disturb the ecology with our agricultural landscape, there are going to be consequences – even with the most ecologically benign approaches, such as crop rotation,” Seufferheld said. “Understanding the interplay of ecology and evolution will allow us to design more sustainable agricultural practices while minimizing undesirable consequences.”
No Country for Old GenesNews
Our modern world is radically different from the one we evolved in, and that creates a mismatch between the environment our genes were evolved to face, and the world those genes now encounter. A new review looks at how certain genes that benefited humans in our genetic past now predispose us to disease in old age.READ MORE
CRISPR Editing Stops HIV Virus in Infected CellsNews
Human immunodeficiency virus-1 (HIV-1) infection is a chronic disease affecting more than 35 million people worldwide. The infection can be controlled by antiretroviral therapy (ART), but there is still no complete cure. Now, a new study targeting the regulatory genes of the virus using CRISPR/Cas9 has helped block the production of the virus by infected cells.READ MORE
Genetics Help Make a Weed a WeedNews
A study has has found that the success of weedy and invasive plants like the Jerusalem artichoke lies in their genes. Understanding how invasive plants evolve and the genes that enable them to thrive in a new environment is key to better understanding why they are wreaking havoc on natural landscapes and food production around the world.READ MORE