Effect of far-red induced shade-avoidance responses on carbon allocation in arabidopsis thaliana

Abstract

Plants are a very dominant form of life on earth and a large part of human society is based on growing plants. Plants use photosynthesis to turn sunlight and carbon dioxide in the air into sugar. This sugar is used to grow and make all the parts of the plants we're interested in using. Roots, flowers, fruits, and seeds can't make the sugar they need from light, and young growing leaves can't make enough sugar on their own to support their growth. The plant's decisions about where to put the sugar it makes is important to determining how the plant will grow. Since plants spend their lives rooted in a single location, they must be able to cope with whatever challenge comes their way. Since plants need light to grow, one challenge plants face is competition with other plants for light. Plants can sense they are growing in competition with other plants by the change in the color of light when it is reflected off other nearby plants. When they sense this change in light they alter how they grow to attempt to avoid being shaded. Usually this involved trying to grow taller to avoid being shaded by their neighbors. Putting their limited resources into growing taller comes at the expense of growing the fruits and seeds we need from them, as well as making the toxic chemicals plants use to defend themselves against insect pests. I was interested in how the light signals which trigger this change in growth affect where plants put the sugar they make from photosynthesis. I hypothesized that treating plants with light which could trigger this change in growth would affect how sugar moved through the plant. Using a radioactive form of sugar which I could follow as it moved through the plant, I found that in response to light signals which trigger this change in growth causes young, growing leaves to export less of the sugar they make (keeping more for themselves), but fully mature leaves did not change how much sugar they exported. Agriculture is all about getting plants to turn sunlight into products we need and understanding how plants make decisions about where to put their resources will help us develop crops and other plants which can more efficiently make the food and other plant products we depend on.