New research provides an answer: Hot chilies growing in dry areas need more water to produce as many seeds as non-pungent plants, but the Fusarium fungus is less of a threat in dryer environments so chilies in those areas are less likely to turn up the heat. In wetter regions, where Fusarium thrives, wild chilies build up their reserves of spicy capsaicin in self-defense.
“Despite the reduced benefit of pungency in dry environments, hot plants still occur there, as does the deadly fungus. That suggests that the greater presence of non-pungent plants that produce substantially more seeds is the result of a fitness-based tradeoff,” said David Haak, lead author of a paper describing the research published Wednesday (Dec. 21) in Proceedings of the Royal Society B. The Royal Society is the United Kingdom’s academy of science.
Haak, a post-doctoral researcher at Indiana University, conducted the research as part of his doctoral work at the University of Washington. Co-authors of the paper are Leslie McGinnis of the University of Michigan, who did the work while a UW undergraduate; Douglas Levey of the University of Florida and Joshua Tewksbury, a UW biology professor who leads the research group.
The scientists examined pungency differences by comparing the proportion of pungent plants with that of non-pungent plants in 12 populations of wild chilies in southeastern Bolivia along a 185-mile line that gradually progressed from a relatively dry region to a wetter region. They conducted plant censuses in focal populations five times between 2002 and 2009, and tagged plants in each census so they could determine new seedlings the next time.
They found that, starting in the dryer northeast part of the section, 15 to 20 percent of the plants had pungent fruit, and pungency increased along the line toward the wetter southwest, where they never found a single plant that did not produce pungent fruit.
They also selected three populations of chili plants that each produced both pungent and non-pungent fruit and spanned the range of rainfall and pungency differences. They then grew seeds from those plants in the UW Botany Greenhouse to examine what affect water availability had on pungency.
The 330 plants that resulted from those seeds were grown under identical conditions until they reached their first flowering, then were separated into two groups – one that received plenty of water and one that was stressed by receiving only the amount of water available to plants in the driest area of Bolivia from which seeds were taken.
The scientists found that under water-stressed conditions, non-pungent plants produced twice as many seeds as pungent plants. That suggests the pungent plants trade some level of fitness for protection from the Fusarium fungus, Haak said.
The researchers determined the pungent plants have developed a reduced efficiency in water use, so in dryer areas they produce fewer seeds and are more limited in reproduction. In wetter areas, non-pungent plants are at a reproductive disadvantage because they are much more likely to have their seeds attacked by the fungus.
“It surprised us to find that the tradeoff to produce capsaicin in pungent plants would involve this major physiological process of water-use efficiency,” Haak said.
He noted that over the entire range, 90 to 95 percent of the chili fruits had some level of fungal infection, and pungent plants were better able to defend themselves.
The research was funded by grants from the National Science Foundation; the National Geographic Society; Sigma Xi, the scientific research society; and the UW Department of Biology.
For more information, contact Haak at 206-913-8472 or email@example.com; or Tewksbury at 206-616-2129 or firstname.lastname@example.org.
Vince Stricherz | Newswise Science News
Cloud Formation: How Feldspar Acts as Ice Nucleus
09.12.2016 | Karlsruher Institut für Technologie
Closing the carbon loop
08.12.2016 | University of Pittsburgh
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
08.12.2016 | Life Sciences
08.12.2016 | Physics and Astronomy
08.12.2016 | Materials Sciences