BTI researchers discover interactions between plant and insect-infecting viruses

June 13, 2019

Aphids and the plant viruses they transmit cause billions of dollars in crop damage around the world every year. Researchers in Michelle Heck's lab at the USDA Agricultural Research Service and Boyce Thompson Institute are examining the relationship at the molecular level, which could lead to new methods for controlling the pests.

Heck's group used recently developed small RNA sequencing techniques to better understand how plant viruses interact with aphids. In an unanticipated discovery, Heck and her team uncovered what may be the first example of a plant virus and an insect virus cooperating to increase the likelihood that both viruses will spread to other plant and aphid hosts.

The work was published in the May 22 issue of Phytobiomes journal. The researchers focused on the green peach aphid (Myzus persicae), which transmits more than 100 different plant viruses and feeds on a wide variety of crops, including peaches, tomatoes, potatoes, cabbage, corn and numerous others.

Potato leafroll virus (PLRV) is of particular concern because it can reduce potato yield by more than 50%, causing 20 million tons of annual global yield losses.

"The most interesting finding of this research is that PLRV suppressed the aphid's immune system, and this suppression was mediated by a single virus protein, the P0 protein," says Jennifer Wilson, a co-first author on the paper. Wilson is a PhD candidate in the School of Integrative Plant Science (SIPS) at Cornell University and is conducting her thesis research with Dr. Heck.

P0 is a PLRV protein that is expressed inside plant tissue but not inside the aphids. While P0 had been previously shown to suppress plants' immune systems, the protein's impact on the insect's immune system was a surprise to the researchers.

"We don't know if the aphids ingest P0 from the plant or not, but we do know that when P0 is present in the plant, the aphids' immune systems are suppressed," explains Wilson.

One critical result of the insect's immune system being hampered is an increase in the proliferation of an insect virus, Myzus persicae densovirus (MpDNV). The researchers also found that aphids with more copies of MpDNV were more likely to have wings.

Because green peach aphids rarely have wings until the weather turns colder in the fall, this increase in winged insects could mean increased spread of PLRV and MpDNV to new hosts all summer long, a synergistic effect that wouldn't happen as much if the aphids were infected with only one of the viruses.

"We think we have found the first example of cooperation between a plant virus and an insect virus," Wilson says. "This cooperation may lead to increased transmission of both viruses."

Wilson and Heck are currently working to test this hypothesis by repeating the experiments in aphids not infected with MpDNV, which Wilson collected last summer from farms in upstate New York.

Future work could include figuring out how MpDNV and the P0 protein could be used to control virus transmission by aphids.

"Developing strategies to block virus transmission in the field is a major goal of our research program," said Heck, also an adjunct assistant professor in SIPS. "Wilson's thesis work is paradigm shifting. Stay tuned for more exciting stuff from her in the near future."
-end-
Researchers from BTI, Cornell and the USDA-ARS collaborated on this study, which was supported by grants from the National Science Foundation and the USDA.

CITATION: Pinheiro, PV, Wilson, JR, et al., "Plant Viruses Transmitted in Two Different Modes Produce Differing Effects on Small RNA-Mediated Processes in Their Aphid Vector", Phytobiomes (2019) 3:71-81.

Boyce Thompson Institute

Related Immune System Articles from Brightsurf:

How the immune system remembers viruses
For a person to acquire immunity to a disease, T cells must develop into memory cells after contact with the pathogen.

How does the immune system develop in the first days of life?
Researchers highlight the anti-inflammatory response taking place after birth and designed to shield the newborn from infection.

Memory training for the immune system
The immune system will memorize the pathogen after an infection and can therefore react promptly after reinfection with the same pathogen.

Immune system may have another job -- combatting depression
An inflammatory autoimmune response within the central nervous system similar to one linked to neurodegenerative diseases such as multiple sclerosis (MS) has also been found in the spinal fluid of healthy people, according to a new Yale-led study comparing immune system cells in the spinal fluid of MS patients and healthy subjects.

COVID-19: Immune system derails
Contrary to what has been generally assumed so far, a severe course of COVID-19 does not solely result in a strong immune reaction - rather, the immune response is caught in a continuous loop of activation and inhibition.

Immune cell steroids help tumours suppress the immune system, offering new drug targets
Tumours found to evade the immune system by telling immune cells to produce immunosuppressive steroids.

Immune system -- Knocked off balance
Instead of protecting us, the immune system can sometimes go awry, as in the case of autoimmune diseases and allergies.

Too much salt weakens the immune system
A high-salt diet is not only bad for one's blood pressure, but also for the immune system.

Parkinson's and the immune system
Mutations in the Parkin gene are a common cause of hereditary forms of Parkinson's disease.

How an immune system regulator shifts the balance of immune cells
Researchers have provided new insight on the role of cyclic AMP (cAMP) in regulating the immune response.

Read More: Immune System News and Immune System Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.