Can bright lights optimise grass-sourced food anthocyanins?
The study, published in HortScience, looked at ways to improve the production of anthocyanins in turfgrasses like rough bluegrass using different wavelengths of high-intensity light – finding that optimal growing conditions could double the commercial yield of the high-value functional ingredient compared to currently used plant sources and methods.
Led by Dominic Petrella from Ohio State University, USA, the team noted that while anthocyanins have become sought-after natural products, the small number of plants that naturally produce anthocyanins has limited their widespread use.
They added that non-conventional plants like turfgrasses may be one way to meet the increasing demand for anthocyanins.
"The anatomy and perennial nature of turfgrasses make them attractive anthocyanin production systems," Petrella said. "Rough bluegrass (Poa trivialis L.) is an attractive anthocyanin production system, since leaf tissue can be harvested while preserving meristematic tissues that allow new leaves to rapidly grow, thereby allowing multiple harvests in a single growing season and greater anthocyanin yields."
Indeed, through the use of artificial high-intensity lights, it has been suggested that turfgrasses like rough bluegrass could be a sustainable and commercially viable source of anthocyanins for the food and nutrition sectors.
"Our data show that the anthocyanin content of rough bluegrass after high-light treatment is comparable to or greater than many common fruits and vegetables, particularly red leaf lettuce, and consists of the same anthocyanins," Petrella said.
Furthermore, analysis by the team has suggested that the use of turfgrasses over an entire growing season could potentially increase anthocyanin yield by two-fold over currently used plant sources.
"These methods may help increase both the environmental and economic sustainability of anthocyanin extract production," they said.
There's grass in the lab, let's do science...
Petrella and his team set up a series of light experiments designed to determine the optimal conditions that favour anthocyanin production in rough bluegrass.
First, the team tested whether treatment with high-intensity light could increase anthocyanin content, and then they determined the wavelength(s) of light capable of upregulating anthocyanin synthesis to optimise light conditions.
They reported that when exposed to constant high-intensity white light, rough bluegrass plants significantly increased anthocyanin concentration compared to untreated plants.
Indeed, light-treated plants showed an average 118-fold increase in anthocyanin content, and accumulated anthocyanins in both leaf blades and sheath tissue, said the team.
To determine the primary wavelength(s) of light responsible for upregulating anthocyanin in this way the team then used dark-grown and light-grown rough bluegrass seedlings which were exposed to blue, red, and far-red LED lights.
They found that blue light, at intensities between 150 and 250 mmol·m-2·s-1, was the only wavelength that increased anthocyanin content. However, when red light was applied with blue light at 30% or 50% of the total light intensity, anthocyanin content was increased compared with blue light alone.
Petrella also commented that a major advantage of using turfgrass for anthocyanin production is the ability to harvest leaves containing anthocyanin numerous times throughout a single growing season. In fact, results from the experiment showed that rough bluegrass plants maintain the ability to produce large quantities of anthocyanin over time, even after aggressive harvesting, the authors noted.
Volume 51, Number 9, Pages 1111-1120, doi: 10.21273/HORTSCI10878-16
“Anthocyanin Production Using Rough Bluegrass Treated with High-Intensity Light”
Authors: Dominic P. Petrella, et al