During climate extremes, plants cannot produce sufficient energy-rich carbon compounds through photosynthesis and they become dependent on stored reserves.
During climate extremes, plants cannot produce sufficient energy-rich carbon compounds through photosynthesis and they become dependent on stored reserves. According to current understanding, these reserves are only formed when the supply of photosynthesis products exceeds demand to support processes like growth. Scientists from the Max Planck Institute for Biogeochemistry demonstrate that trees continue to form reserves even during long periods of starvation. To achieve this, trees stop growing and even digest non-essential energy-rich components. This knowledge can be used to improve predictions of how trees will respond to climate change.
Trees and entire forests worldwide are threatened by increasing climate extremes and ensuing insect infestations. As sessile organisms, trees cannot escape threatening environmental conditions and must adapt their metabolic processes to confront the threats. Crucially important for plants is the production of energy-rich sugar molecules (carbohydrates) by photosynthesis. These compounds serve as both energy sources and basic building blocks for all metabolic processes. During climate extremes such as prolonged drought or heat, photosynthesis is impaired and trees produce less carbohydrates, because CO2 uptake declines and water is scarce. The demand for energy-rich sugars is then not met and plants have to rely on stored reserves to maintain vital metabolic processes. When reserves become depleted, plants may starve to death or become vulnerable to disease and insect attacks as the defense system fails.
Despite their critical role, it was assumed until now that reserves like soluble sugars, starch or fats are only formed when photosynthetic conditions are favorable and their rate of production exceeds the demand from other functions such as growth. "From an evolutionary perspective that doesn't make sense. Trees have to survive for decades before they can reproduce, and a reliable source of quickly available reserves plays a crucial role in surviving frequent unfavorable periods" underlines Dr. Henrik Hartmann, group leader at the Max Planck Institute for Biogeochemistry (MPI-BGC) in Jena. "Why should a tree invest in growth instead of ensuring immediate and future survival by accumulating more reserves?"
Read more at Max-Planck-Gesellschaft
Photo Credit: Naturell via Pixabay
