UCLA life scientists have brought to light new laws that determine the construction of leaf vein systems as leaves grow and evolve. These basic mathematical rules can now be used to better predict the climates of the past using the fossil record.
Researchers get to estimate original leaf sizes from just a fragment of a leaf through a range of fundamental implications of global ecology. This in turn can elevate scientists' prediction and interpretation of climate in the leaf fossils.
Leaf veins are of tremendous significance in a plant's life, providing them with much important nutrients and water that leaves need to conduct photosynthesis and supporting them in capturing sunlight. Leaf size is also of great importance for plants' adaptation to their environment, with smaller leaves being found in drier, sunnier places.
However, little has been known about what determines the architecture of leaf veins. Mathematical correlation between leaf vein systems and leaf size have the potential to explain important natural patterns. The new UCLA research focused on these correlations.
"We found extremely strong, developmentally based scaling of leaf size and venation that has remained unnoticed until now," said Lawren Sack, a UCLA professor of ecology and evolutionary biology and lead author of the research.
Federally funded by the National Science Foundation, the team of Sack, UCLA graduate student Christine Scoffoni, three UCLA undergraduate researchers and colleagues at other U.S. institutions had check out hundreds of plant species worldwide using computer tools to focus on high-resolution images of leaves that were chemically treated and stained to allow sharp visualization of the veins.
“The team discovered calculable relationships that hold across different leaves throughout the globe. Larger leaves had their major veins spaced further apart according to a clear mathematical equation, regardless of other variations in their structure (like cell size and surface hairiness) or physiological activities (like photosynthesis and respiration),” Sack said.
Sack further added, "It's amazing what is waiting to be discovered in plant biology. It seems limitless right now. The previous century is known for exciting discoveries in physics and molecular biology, but this century belongs to plant biology. Especially given the centrality of plants for food and biosphere sustainability, more attention is being focused, and the more people look, the more fundamental discoveries will be made."
The research was published in the journal Nature Communications.