Nav: Home

How plants prevent oxidative stress

June 08, 2017

When excess light energy is absorbed by plants during photosynthesis, harmful reactive oxygen species are produced. These reactive oxygen species break down important structures such as proteins and membranes, preventing them from functioning properly. Researchers have discovered the system used by plants to prevent oxidative stress and to safely carry out photosynthesis.

A research team led by Associate Professor MIYAKE Chikahiro (Kobe University Graduate School of Agricultural Science) made this discovery, which was reported in 11 journals.

The light energy use of most photosynthesizing organisms is saturated at 25-50% of sunlight. In other words, they are routinely exposed to more light energy than they need for photosynthesis. When leaves are irradiated by excess light energy, the chloroplasts that carry out photosynthesis can easily suffer oxidative stress and stop photosynthesizing.

Previously this team was the first to clarify the mechanism behind the production of reactive oxygen species. Building on these results, they developed the "pulse method" to artificially induce oxidative stress. They discovered the P700 oxidation system, used by plants to suppress the production of reactive oxygen species.

P700, a chlorophyll in the reaction center of photosystem I, is the particle that transforms oxygen into reactive oxygen species. Since the late 1980s scientists knew that P700 oxidation can be seen in environments with excess sunlight, but this team is the first to define its role. The team also discovered that P700 oxidation is essential for the growth of cyanobacteria, the ancestors of higher plant chloroplasts, and it also functions in algae, moss, ferns, gymnosperms and angiosperms.

When oxidized P700 (P700+) accumulates in the P700 oxidation system it lowers the ratio of light-stimulated P700 (P700*). P700* produces reactive oxygen species by giving electrons to oxygen, producing superoxide radicals, or producing triplet P700 that gives light energy to oxygen. The accumulation of P700 suppresses the production of reactive oxygen species via the photosynthetic electron transport system. The research team also clarified two strategies that photosynthesizing organisms have acquired to enable the P700 oxidation system to function and accumulate P700+.

The discovery of the P700 oxidation system and its role shows that photosynthetic organisms use this system as a physiological function that is indispensable in outdoor environments. This system, common to photosynthetic organisms, starts to function when excess light energy is present (caused by environmental stresses such as strong sunlight, drought, or lack of nutrients). As a result, P700 is oxidized to produce P700+. When P700 oxidation occurs, this indicates that dangerous reactive oxygen species will also be produced due to excess sunlight.

The group focused on the production of P700+ as a warning marker for reactive oxygen species, and are developing equipment to detect P700+. Monitoring P700+ could enable the early detection of risks from oxidative stress. Treatment of reactive oxygen species production using the pulse method could enable scientists to evaluate plant resistance to reactive oxygen species. The team will continue to investigate these avenues.
-end-


Kobe University

Related Photosynthesis Articles:

Scientists design molecular system for artificial photosynthesis
A molecular system for artificial photosynthesis is designed to mimic key functions of the photosynthetic center in green plants -- light absorption, charge separation, and catalysis -- to convert solar energy into chemical energy stored by hydrogen fuel.
Photosynthesis in the dark? Unraveling the mystery of algae evolution
Researchers compared the photosynthetic regulation in glaucophytes with that in cyanobacteria, to elucidate the changes caused by symbiosis in the interaction between photosynthetic electron transfer and other metabolic pathways.
Mechanism behind the electric charges generated by photosynthesis
Photosynthesis requires a mechanism to produce large amounts of chemical energy without losing the oxidative power needed to break down water.
Research shows global photosynthesis on the rise
Researchers found a global historic record by analyzing gases trapped in Antarctic snow to see the rapid rise in photosynthesis over the past 200 years.
Artificial photosynthesis steps into the light
Rice University leads a project to create an efficient, simple-to-manufacture oxygen-evolution catalyst that pairs well with semiconductors for advanced solar cells.
New study shines light on photosynthesis
Researchers have solved a longstanding mystery in photosynthesis, a process used by plants and other organisms to convert light energy into chemical energy.
Study: Viruses support photosynthesis in bacteria -- an evolutionary advantage?
Viruses propagate by infecting a host cell and reproducing inside.
Accelerated chlorophyll reaction in microdroplets to reveal secret of photosynthesis
The research team of DGIST's fellow Hong-Gil Nam, discovered the natural control of chlorophyll activity.
Mechanism for photosynthesis already existed in primeval microbe
A Japanese research team has discovered an evolutionary model for the biological function that creates CO2 from glucose in photosynthesis.
WSU researchers discover unique microbial photosynthesis
Researchers at Washington State University have discovered a new type of cooperative photosynthesis that could be used in engineering microbial communities for waste treatment and bioenergy production.

Related Photosynthesis Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Anthropomorphic
Do animals grieve? Do they have language or consciousness? For a long time, scientists resisted the urge to look for human qualities in animals. This hour, TED speakers explore how that is changing. Guests include biological anthropologist Barbara King, dolphin researcher Denise Herzing, primatologist Frans de Waal, and ecologist Carl Safina.
Now Playing: Science for the People

#SB2 2019 Science Birthday Minisode: Mary Golda Ross
Our second annual Science Birthday is here, and this year we celebrate the wonderful Mary Golda Ross, born 9 August 1908. She died in 2008 at age 99, but left a lasting mark on the science of rocketry and space exploration as an early woman in engineering, and one of the first Native Americans in engineering. Join Rachelle and Bethany for this very special birthday minisode celebrating Mary and her achievements. Thanks to our Patreons who make this show possible! Read more about Mary G. Ross: Interview with Mary Ross on Lash Publications International, by Laurel Sheppard Meet Mary Golda...