Parasitic plants conspire to keep hosts alive

February 23, 2021

The plant that encourages kissing at Christmas is in fact a parasite, and new research reveals mistletoe has an unusual feeding strategy.

Like other plants, mistletoe is capable of using sunlight to create its own food, a process called photosynthesis. However, it prefers to siphon water and nutrients from other trees and shrubs, using "false roots" to invade its hosts.

"Plants are autotrophic, they make their own food. Humans are heterotrophic, we eat it," explained UC Riverside plant-insect ecologist Paul Nabity. "Mistletoe are mostly heterotrophic, but they can switch if they want to."

Nabity's team found when two mistletoes invade the same tree, they increase photosynthesis to get the nutrients they need, essentially sharing the tree and causing it less harm.

"They seem to know when they're attacking the same host, and can reduce the virulence of their attack," Nabity said.

A new paper describing this finding was published today in the journal Current Biology.

The Christmas mistletoe is a European species that tends to attack apple and other hardwood trees in central California. For this experiment, the researchers examined a native species of mistletoe found throughout the Sonoran and Mojave deserts that often grows on acacia, palo verde or mesquite trees.

When researchers removed one of two mistletoes from a branch, they saw the plant left behind did not increase its photosynthesis, and in some cases reduced its water intake.

"It appears that the remaining mistletoe recognized it was no longer competing for resources," Nabity said.

Often times, birds feed from and guard a fruiting mistletoe and in the process, defecate seeds into the same tree from which they came. A tree full of related mistletoes increases the parasite load for the host, though the infection may not be as severe as it otherwise would be if infected with unrelated plants.

Nabity, who studies interactions between plants and insects, explained that communication among mistletoes is possible through a variety of methods. They are connected to a host's xylem, the tissue that trees use to move water and nutrients from the roots. It's possible the mistletoes send messages using the xylem. It's also possible they may "smell" one another.

Plants produce chemical compounds and release them through their pores. These compounds evaporate quickly into the air, sending signals that can be received down wind.

However it is that mistletoes communicate, Nabity says they doesn't necessarily need to be removed from infected trees.

Forest managers have long maintained that removal will increase tree health. Though this may be true for an individual tree, mistletoe has an important role ecologically, benefitting birds and pollinators. It tends to flower in winter when nectar or pollen from many other plants is not yet available.

Not only does mistletoe help other species, it may not hurt trees or shrubs as much as once feared.

"Don't remove mistletoe because you think they're all bad," he said.

University of California - Riverside

Related Photosynthesis Articles from Brightsurf:

During COVID, scientists turn to computers to understand C4 photosynthesis
When COVID closed down their lab, a team from the University of Essex turned to computational approaches to understand what makes some plants better adapted to transform light and carbon dioxide into yield through photosynthesis.

E. coli bacteria offer path to improving photosynthesis
Cornell University scientists have engineered a key plant enzyme and introduced it in Escherichia coli bacteria in order to create an optimal experimental environment for studying how to speed up photosynthesis, a holy grail for improving crop yields.

Showtime for photosynthesis
Using a unique combination of nanoscale imaging and chemical analysis, an international team of researchers has revealed a key step in the molecular mechanism behind the water splitting reaction of photosynthesis, a finding that could help inform the design of renewable energy technology.

Photosynthesis in a droplet
Researchers develop an artificial chloroplast.

Even bacteria need their space: Squished cells may shut down photosynthesis
Introverts take heart: When cells, like some people, get too squished, they can go into defense mode, even shutting down photosynthesis.

Marine cyanobacteria do not survive solely on photosynthesis
The University of Cordoba published a study in a journal from the Nature group that supports the idea that marine cyanobacteria also incorporate organic compounds from the environment.

Photosynthesis -- living laboratories
Ludwig-Maximilians-Universitaet (LMU) in Munich biologists Marcel Dann and Dario Leister have demonstrated for the first time that cyanobacteria and plants employ similar mechanisms and key proteins to regulate cyclic electron flow during photosynthesis.

Photosynthesis seen in a new light by rapid X-ray pulses
In a new study, led by Petra Fromme and Nadia Zatsepin at the Biodesign Center for Applied Structural Discovery, the School of Molecular Sciences and the Department of Physics at ASU, researchers investigated the structure of Photosystem I (PSI) with ultrashort X-ray pulses at the European X-ray Free Electron Laser (EuXFEL), located in Hamburg, Germany.

Photosynthesis olympics: can the best wheat varieties be even better?
Scientists have put elite wheat varieties through a sort of 'Photosynthesis Olympics' to find which varieties have the best performing photosynthesis.

Strange bacteria hint at ancient origin of photosynthesis
Structures inside rare bacteria are similar to those that power photosynthesis in plants today, suggesting the process is older than assumed.

Read More: Photosynthesis News and Photosynthesis Current Events 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