The world's population needs more and more food. What will the plants of the future look like? These "champions" should be high-yielding and resistant. But what defence mechanisms do they have against oxidative stress? The aim of this project is to investigate in detail, together with the students, the chemical defence mechanisms of plants against the increasing oxidative stress, especially from ozone.

Project description:

Over the past 100 years, the concentration of ground-level ozone (_O3) has doubled due to growing industrialisation and the increase in traffic. The formation of ground-level ozone requires both anthropogenically emitted nitrogen oxides (NOx = NO + _NO2) and organic trace gases, mainly emitted by plants, and sunlight. Both humans and plants are currently exposed to increased ozone concentrations. How harmful ozone is to humans and plants depends primarily on the amount of ozone absorbed. If the ozone flow into the plant exceeds a certain level, discolouration and necrosis initially occur in isolated areas of the plant leaf and the plant may subsequently die. Ozone alone causes several billion dollars worth of damage to agricultural plants in the global economy every year.

It has long been known that different plant species, but also different genotypes of a species (e.g. different tobacco varieties) react very specifically with regard to their susceptibility to ozone pollution. For example, sensitive tobacco varieties are used as bioindicators for the occurrence of high ozone pollution. This different sensitivity can have several causes. All living organisms that live in an oxygen-rich environment have antioxidant systems in their cells to detoxify the permanently formed reactive oxygen species. If these defence systems can no longer cope with the ozone dose absorbed, the leaves are visibly and permanently damaged.

We were only recently able to show that ozone-tolerant tobacco varieties synthesise a semi-volatile substance in their hairs on the leaf surface and ''spray'' it onto the plant surface, which renders ozone harmless on the leaf surface. So there are plants that synthesise their own ''protective cream'' to protect themselves from ozone. These plants are already very well prepared for the expected future increase in ozone.

With the active support of the pupils as young scientists, we want to measure the spatial distribution of the ozone concentration in the Oberpinzgau region and estimate the uptake of ozone in test plants (ozone dose determination) as a first approach. To this end, the pupils will work together with the university experts to initially produce and programme "low-cost" research stations for ozone, NOx, temperature, etc., as well as grow test plants that are to serve as bioindicators. These research stations will be set up in the students' home towns and supervised by them on site in order to generate a unique data set that will serve to better understand the spatial heterogeneity and distribution of ozone in the inner Alpine valley. In addition, the spatial distribution of the effective ozone dose for plants in the Oberpinzgau will be determined for the first time.

In a second approach, the scientific question of why some plant genotypes react extremely sensitively to ozone, while others are highly resistant to ozone, will be investigated under controlled conditions in the laboratory. To this end, plants are enclosed in a glass container and treated with ozone or other oxidants and the reaction of the plants to this is investigated. State-of-the-art, extremely powerful techniques are used here to detect the reaction products of ozone with semi-volatile compounds, which are suspected to be on the leaf surfaces of the plants, with high temporal resolution. With these investigations, the project is at the cutting edge of research in the field of plant defence against abiotic stress.

Project description:

Over the last 100 years the concentration of ground-level ozone (_O3) has doubled due to increasing industrialisation and traffic. For the formation of ground-level ozone anthropogenically emitted nitrogen oxides (_NOx = NO + _NO2), organic trace gases emitted primarily from plants and sunlight are necessary. Both humans and plants are exposed to increased ozone concentrations. How harmful ozone is to humans and plants depends primarily on the absorbed amount of ozone. If the ozone flux into the plant exceeds a certain amount discolorations and necroses of isolated spots on the plant leaves are formed and can further lead to vegetation loss. Due to ozone damage on agricultural crops billions of dollars are annually lost for the global economy.

It is known that various plant species but also different genotypes of a species (e.g. various types of tobacco) react very specifically to ozone exposure. For example, sensitive tobacco types are used as bio indicators for the occurrence of a high ozone dose. This can have several causes. Plants usually have antioxidant systems in their cells to detoxify the permanently formed reactive oxygen species, like ozone (O3) or hydroperoxides (ROOH). If these defence systems do not manage to process the absorbed ozone dose, the leaves get damaged. We recently showed that ozone-tolerant tobacco varieties synthesise a semi-volatile substance in their trichomes on the leaf surface and "spray" it onto the plant surface. The substance decreases the amount of ozone entering the leaf. So there are plants that synthesise their own ''protective cream'' to protect themselves from ozone. These plants are already well prepared for the increasing ozone levels in the future.

With the energetic support of the students as young scientists, we want to measure the spatial distribution of the ozone concentration in the valley Oberpinzgau. In a first approach we estimate the uptake of ozone in experimental plants. Together with the university experts the students will build and program "low-cost" research stations for ozone, NOx, temperature, radiation and humidity. They will test bean plants which should serve as bio indicators. These research centres will be set up in the students' home to generate a unique dataset that will help to a better understanding of the spatial heterogeneity and distribution of ozone in an inner alpine valley. In addition, the spatial distribution of the effective ozone dose for plants in the Oberpinzgau region will be determined for the first time.

In a second approach we will investigate under controlled conditions in the laboratory, why some plant genotypes react extremely sensitively to ozone while others have a high resistance to ozone. For this purpose, plants are enclosed in a glass cuvette and treated with ozone or other oxidants. With highly sensitive instruments we will detect the reaction products of ozone with semi-volatile compounds, which are suspected on the leaf surfaces of the plants. With these investigations the project is focusing on state of the art research in the field of plant defence against abiotic stress.