This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Bees are the most important pollinators of flowering plants, and approximately 10% of flowering plants are functionally specialized for buzz pollination. Buzz pollination is a mechanism in which pollen can be extracted from flowers only through the application of mechanical vibrations.
Many important crops, such as tomatoes, eggplants and blueberries, are buzz-pollinated because they conceal their pollen in so-called poricidal anthers—floral structures with only a minute opening through which pollen can be released only when mechanical vibrations are applied. In a new study recently published in Nature Communications, a research team at the Department of Botany and Biodiversity Research at the University of Vienna found that the shape of the pore determines how pollen is released. Comparing more than 500 plant species, the researchers found that pores either carry a spatulate structure termed a "scoop" or lack such a scoop.
Tomatoes lack scoops, but anthers of the large tropical plant family Melastomataceae, for example, commonly bear them. Doctoral candidate Benjamin Lazarus from the University of Vienna experimentally tested whether the "scoop" has a specific function—and found that it does. Lazarus applied mechanical vibrations to single anthers, mimicking bee vibrations by placing stamens in a specifically constructed artificial vibration setup.
He then used high-speed video to film the pollen clouds expelled from different anthers and analyzed the scattering angles of the pollen clouds as well as the velocity at which they moved through the air. Lazarus found that anthers bearing scoops expel their pollen in narrower, more targeted jets than anthers lacking such scoops, which normally scatter pollen in broad clouds. Furthermore, scoop-bearing anthers release pollen at faster speeds.
"Our new findings have important implications for the functionality of buzz pollination," said study lead Agnes Dellinger from the University of Vienna. Releasing pollen in narrow jets may allow plants to target specific areas on bees' bodies and place pollen in a more controlled manner. "Accuracy in pollen placement is important for plants because it can improve pollination success and at the same time enables plants to place pollen in 'safe spots' where bees can't groom and collect it off their bodies.
At the same time, faster pollen release may allow plants to eject pollen across larger distances and implant it more deeply in the fur of bees, thereby again reducing pollen loss," Dellinger explained. The team further found that scoop-shaped pores are sensitive in their functionality to the exact nature of the vibration applied—while targeted pollen release showed a cyclical pattern perfectly in line with vibrations at 300 Hz and 400 Hz, pollen release became "messy" and chaotic at low-frequency vibrations of around 200 Hz. The finding that the functionality of the scoop-shaped pore depends on vibration frequency is important because different bee species vibrate flowers at different frequencies, meaning that some bees may remove greater amounts of pollen from flowers than others.
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