Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New research reveals why chili peppers are hot

14.08.2008
Despite the popularity of spicy cuisine among Homo sapiens, the hotness in chili peppers has always been something of an evolutionary mystery.

A plant creates fruit in order to entice animals to eat and disperse its seeds, so it doesn't make sense for that fruit to be painfully hot, said University of Florida zoology professor and evolutionary ecologist Douglas Levey.

But according to new research by Levey and six colleagues from other universities, chilies have a very good reason to make themselves hot. It boils down to protection.

Based on research on wild chili plants in rural Bolivia, the scientists found that the leading cause of seed mortality is a fungus called Fusarium. The fungus invades the fruits through wounds made by insects and destroys the seeds before they can be eaten and dispersed.

Capsaicin, the chemical that makes the peppers hot, drastically slows microbial growth and protects the fruit from Fusarium. And while capsaicin deters local mammals, such as foxes and raccoons, from consuming the chilies, birds don't have the physiological machinery to detect the spicy chemical and continue to eat the peppers and disperse seeds, Levey said.

The researchers' findings will be released today in a paper published online by the Proceedings of the National Academy of Sciences.

Levey and his colleagues were able to arrive at these conclusions because at least three of the approximately 15 species of chilies that grow in the Bolivian wild are polymorphic for pungency, which means that some individuals of those species produce pungent fruit and others produce non-pungent fruit. This provided the researchers with natural experimental conditions under which they could compare Fusarium attack on fruits with and without capsaicin.

Upon studying various chili pepper plants, the researchers observed a clear correlation between high levels of capsaicin and low seed mortality due to fungal growth, Levey said.

And the chemical doesn't just help the plants that produce it, either. Levey said the consumption of chilies can help protect humans from the dangerous diseases that are so plentiful in tropical climates.

"The use of chili peppers as a spice has spread to nearly every culture within 20 degrees of the equator, and it tends to decline as you move toward the poles," Levey said.

The capsaicin in chilies, one of the first plants domesticated in the New World, may have been used to protect human food from microbial attack long before refrigeration or artificial preservatives were available, he said.

One question Levey and his colleagues are still pondering is why any nonhot chilies remain if capsaicin is so beneficial. Their hypothesis is that the production of the chemical comes at a steep price for chili plants.

Levey said the plants that produced hot chilies had seeds with very thin coats – a presumed consequence of sacrificing the production of lignin, a complex molecule that makes up the protective seed coat, in favor of the production of capsaicin.

This phenomenon represents an interesting tradeoff between chemical and physical seed protection and demonstrates the power of natural selection, Levey said.

At higher elevations, where moisture is high and Fusarium fungus is rampant, the scientists found that 100 percent of the plants produced hot chilies. In the drier lowlands, where fungus is less of a problem, only 40 percent of the plants produced fiery fruits. The remainder spent more resources developing thick seed coats, which protect against the devastating ant populations common to lower areas.

While all of the plants look identical, telling the difference between hot and non-hot chilies is not difficult, Levey said.

"Just pop one in your mouth," he said. "You'll find out pretty quick."

Douglas Levey | EurekAlert!
Further information:
http://www.ufl.edu

More articles from Life Sciences:

nachricht Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel

nachricht Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Powerful IT security for the car of the future – research alliance develops new approaches

The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.

Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...

Im Focus: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

In focus: Climate adapted plants

25.05.2018 | Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

 
Latest News

In focus: Climate adapted plants

25.05.2018 | Event News

Flow probes from the 3D printer

25.05.2018 | Machine Engineering

Less is more? Gene switch for healthy aging found

25.05.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>