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| How roots influence leaf growth | |
| Leslie Sieburth an associate professor in biology at the University of Utah together with graduate student Jaimie Van Norman have discovered a gene that allows the roots of Arabidopsis to tell the leaves to stop growing in conditions of stress - when water is scarce or other negative environmental conditions. Stress hormones such as cytokinin and abscisic acid play a role when plant roots send signals to all parts above ground: stems, leaves, flowers and fruit, but how do genes in the roots control these chemical signals? How do roots affect leaf growth in a given plant from large and lush in a warm humid climate to small and tough in dry conditions and drought? The research at Utah University has revealed part of the answer. It showed that the gene named Bypass1 could be manipulated to change the way leaves develop. In a normal plant Bypass1 keeps the lever closed (this stops the production of growth inhibiting carotenoid byproducts). When conditions are bad, Bypass1 opens the lever and the carotenoid byproducts flow freely from the roots to all the buds (actively growing parts) telling them to stop growing. As a result the leaves grow smaller, and plant growth is more compact (the development of flowers and fruit is usually reduced and in some cases aborted). So in conditions of dryness and drought the roots limit the growth of the leaf area and thus the loss of moisture through transpiration. The study did not reveal exactly what stimuli cause Bypass1 to switch on but lack of water, compacted soil and other conditions that threaten the survival of the plant are clearly involved. Because plants are immobile organisms thay have to sense their environment both above and below the ground and then respond to the changes. The research indicates that the hormone involved in the signalling process is a carotenoid Through further research and development, this important discovery can lead to an enormous influence on agricultural and horticultural production once more is known about the biochemistry and the way to manipulate it to advantage. For more information contact Leslie Sieburth, Tel 001 801 587 9378, E-mail: sieburth@biology.utah.edu www.utah.edu |
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