Abstract
In order to analyze root development under water deficit condition, we developed a novel system to treat soil-grown plants readily with draught. When rice plants were grown in the containers, called "Root box", seminal roots of them were more elongated in water- stressed condition than in control condition. Number of crown roots was decreased in the water-stressed condition. Microarray analysis has revealed that number of auxin-related and auxin-inducible genes were up-regulated in root tips of water-stressed rice plants. These genes include ILR1 and IAR3 encoding enzymes which catalyze removal of amino acid moieties from IAA-amino acid conjugates. Consistent with this observation, level of IAA was higher in the root tips of the water-stressed rice plants, suggesting that the elevated level of IAA is one of key factors for the enhanced root elongation under water-stressed condition. Since there were no difference in length of cortical cells in root tips between control and the water-stressed conditions, the enhanced root elongation under water-stressed condition may be caused by increased cell division.
