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
Novel mechanisms of action discovered for the skin cancer medication Imiquimod
21.10.2016 | Technische Universität München
Second research flight into zero gravity
21.10.2016 | Universität Zürich
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.
In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...
'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.
Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
21.10.2016 | Health and Medicine
21.10.2016 | Information Technology
21.10.2016 | Materials Sciences