A pollinator is anything that helps carry pollen from the male part of the flower (stamen) to the female part of the same or another flower (stigma) . Honeybees are pollinators for a wide range of crops. However, according to new research published in the Nature Communications Journal, that same flexibility may put plants at risk of disease.
Begining of Discovery
University of Pittsburgh biologists showed that a variety of viruses travel on pollen, especially in areas close to agriculture where honeybees predominate, in the first study to take a broad look at virus hitchhikers on pollen grains.
“Our understanding of viruses on pollen in general was nonexistent prior to this study,” said Professor Tia-Lynn Ashman of the Kenneth P. Dietrich School of Arts and Sciences. The majority of what we know about plant viruses comes from sick agricultural species. We simply had no idea what was out there”.
By sequencing the genetic material present on the pollen grains of 24 plant species from across the United States, the researchers discovered signs of several plant viruses previously shown to travel on pollen, as well as six new species, three new variants of known species, and the incomplete traces of more than 200 previously unknown viruses .
The team, which included biologist James Pipas from the University of Pittsburgh, former Ph.D. student Andrea Fetters, and Ph.D. student Amber Stanley, published their findings in the journal Nature Communications on January 26th, 2022. The tiny of spiky vehicles for plant genetic material known as pollen represent a convenient way for viruses to travel from host to host. It is also a direct path to a plant’s reproductive organs, which are the only parts of the plant where cells are not protected by a hard outer surface. It’s also similar to how viruses enter our bodies through our less-protected noses and mouths.
The Vital of Pollinator
“Pollinators are essentially the go-betweens for plant sex — because plants can’t get up and move to another plant, they rely on an intermediate,” Ashman explained. “So this can be linked to a sexually transmitted disease.”
To get to the point, the researchers discovered that pollen produced by plants with more flowers, which attract pollinators, also harbored a greater variety of viruses. The researchers also discovered a broader range of pollen-borne viruses in areas near human habitation and agriculture. One reason for this pattern, according to Ashman, could be honeybees: because they visit a wide variety of flowers over a large area, they meet all of the criteria for virus transmission. Native pollinators are far more specialized than non-native pollinators.
It’s a lesson not only for how we do a farming, but also for backyard beekeepers.
“Honeybees have the potential to be superspreaders,” Ashman said. “People believe that beekeeping at home benefits pollinators. Nonetheless, when we do something like bring honeybees into the city, we bring everything with them.”
Possibly including all the viruses they pick up on their travels. It will be up to future studies to determine what those viruses are doing, whether they are harming pollinators and plants or, paradoxically, helping them. Regardless, the work demonstrates yet another way that humans can clog the gears when we engineer ecosystems for our own benefit.
 Andrea M. Fetters, Paul G. Cantalupo, Na Wei, Maria Teresa Sáenz Robles, Amber Stanley, Jessica D. Stephens, James M. Pipas, Tia-Lynn Ashman. The pollen virome of wild plants and its association with variation in floral traits and land use. Nature Communications, 2022; 13 (1) DOI: 10.1038/s41467-022-28143-9