A research team from Kobe University led by Associate Professor Miyake Chikahiro and PhD student Takagi Daisuke have reproduced the reaction in which harmful reactive oxygen species are created during plant photosynthesis, and clarified a mechanism behind plant withering.

Plants depend on photosynthesis as an energy source, but when the light energy for photosynthesis is absorbed in excess, harmful reactive oxygen species (ROS) are produced. To deal with reactive oxygen, plants use enzymes, but when plants are exposed to environmental stresses, their ability to photosynthesize is reduced, the ROS removal mechanism cannot keep up with the ROS produced from excess light energy, and plants wither and die.

Professor Miyake's group extracted chloroplasts and thylakoid membranes from leaves, and exposed them to excess light using repetitive short-pulse illumination. As a result, a particle known as "P700" which absorbs light energy within photosystem I stopped functioning, and three types of reactive oxygen species were produced: superoxide radicals (O2 -), hydroxyl radicals (OH・) and singlet oxygen (1O2). They further confirmed that by limiting the flow of electrons to photosystem I the production of reactive oxygen species was suppressed.

For more details, read the news release at the Kobe University website.

Figure: A research team led by Associate Professor MIYAKE Chikahiro and PhD student TAKAGI Daisuke from the Kobe University Graduate School of Agricultural Science have reproduced the reaction in which harmful reactive oxygen species are created during plant photosynthesis, and clarified a mechanism behind plant withering. This discovery could help to ensure stable food supplies by cultivating plants that can withstand environmental stresses such as global warming. The findings were published on March 2 in the online version of Plant Physiology.