Plant immunity; fighting off bark beetles (Introduction)

by David Turell , Sunday, October 02, 2022, 22:34 (574 days ago) @ David Turell

The tress produce obnoxious fragrances:

https://www.the-scientist.com/news-opinion/pine-trees-fragrances-help-neighbors-battle-...

"The herbivores in this study were large pine weevils (Hylobius abietis L.), common pests in European coniferous forests that feed on tree bark and kill young seedlings. Clearcutting of forests amplifies the beetles’ impact; weevils reproduce in the newly created stumps and ravage the seedlings that grow in their place.

"However, conifers aren’t completely defenseless against these dime-sized invaders. Much like kitchen herbs whose scent becomes more potent when crushed or broken apart, Scotch pine (Pinus sylvestris) and other trees emit fragrant molecules when herbivores chew through their bark. These molecules, known as herbivore-induced plant volatiles (HIPVs), repel the herbivore and attract its predators.

"Additionally, Hao Yu, a plant ecophysiologist at the University of Eastern Finland, knew that some tree species use these volatile compounds to communicate with one another, allowing for neighbors of a besieged plant to increase their defenses against whatever animal is attacking them. However, this behavior had never been studied in conifers, which are famous for their belowground networks of fungal communication.

***

"The researchers found that receiver saplings exposed to the HIPVs of infested emitter plants were more resistant to pine weevil damage than those not exposed to infested saplings. These exposed plants emitted more volatiles and boasted more robust resin ducts with a greater cell count. Together, the emission of HIPVs and increased resin production are a strong deterrent to invading bugs. Yu and his colleagues also found higher rates of photosynthesis (which would enable plants to generate the carbon resources needed for volatile and resin production), and increased stomatal conductance, which allows for more airflow to support photosynthesis, in receiver plants exposed to infested plants.

"Combined, these results indicate that HIPVs are a call-to-arms for neighboring pine saplings, telling them to gear up for battle, says biologist Jörg-Peter Schnitzler of Helmholtz Munich Research Center who wasn’t involved in the study.

"The infested tree “is sending out a so-called ‘cry for help,’ and its neighbors are somehow sensing it,” Schnitzler says. “And then [the neighbors] are priming their defense and are more active in defending against an upcoming enemy. That’s really exciting to see./”

Comment: I left out the description of how was studied with saplings in the lab with infected and uninfected trees. The question, of course, is how this developed, naturally or by God.