Breakthrough in Plant Virus Prevention Could Transform Crop Health and Disease Control.
Researchers have made a significant breakthrough in understanding how plants prevent the transmission of viruses to their offspring, which could lead to stronger, more disease-resistant crops. This discovery also holds promise for reducing disease spread from mothers to human children.
Plant viruses often spread across borders via seeds, making it crucial to address how these viruses are transmitted from parent to offspring.
“Viruses can linger in seeds for years, making this a major issue in agriculture,” said Shou-Wei Ding, a distinguished professor at UC Riverside in the Department of Microbiology and Plant Pathology.
Scientists have been puzzled for a century by how mother plants prevent the transmission of viruses to their offspring. A team from UC Riverside has now identified the immune pathway responsible for halting this virus transmission.
The research, published recently, involved identifying this pathway by infecting hundreds of Arabidopsis plants with cucumber mosaic virus. The team discovered genes that enhance resistance to the virus in both the plants and their progeny. This virus can infect over 1,000 plant species and cause a range of symptoms.
Two crucial genes, active only during early seed development, were found to play a key role in the RNA interference pathway. This pathway involves converting genetic information from DNA to RNA and then to proteins. It includes cutting double-stranded RNA into small interfering RNA (siRNA) fragments that help block the production of proteins from foreign viruses.
“Many organisms use siRNAs to control viral infections,” Ding explained. “We believe these plants prevent seed infections because the antiviral RNA interference pathway is active during seed development.”
To test their theory, the researchers created mutant plants by removing two essential genes involved in RNA interference: dicer-like two and dicer-like 4. Without these genes, plants could not produce siRNAs to fight off viral infections, resulting in ineffective antiviral defenses.
Although the mutant plants grew and produced seeds normally, they showed severe symptoms when infected with cucumber mosaic virus. This led to reduced seed production and a tenfold increase in virus transmission, with up to 40% of new seedlings becoming infected.
“We were thrilled by this finding,” Ding said. “It’s the first time we’ve seen such a major change in seed transmission after removing an immune pathway.”
The research team is now investigating how viruses manage to infect a small percentage of seeds in non-mutant plants despite strong immune suppression. Their findings suggest that the virus uses a protein to block the RNA interference pathway in mother plants. Future research will focus on whether enhancing this immune pathway in seeds can further reduce virus transmission.
This discovery has important implications for disease prevention in both animals and humans, as the identified pathway is conserved across various organisms. It could help in preventing severe birth defects, such as microcephaly and other brain abnormalities caused by human viruses like Zika. The team hopes their findings will lead to new methods to reduce vertical Zika transmission during pregnancy.
“We know that Zika virus produces several proteins that block the RNA interference pathway, so it may be possible to prevent vertical transmission by developing new drugs to inhibit these proteins,” Ding said.