Abstract
Wild watermelon (Citrullus lanatus sp. No101117-1) is highly resistant to drought stress, but contribution of the root system to the resistance remains to be characterized. We have demonstrated by proteomic analysis that expression of aRan GTPase (CLRAN) is increased by drought stress. Here, we analyzed developmental mechanisms of wild watermelon roots under drought stress and physiological function of CLRAN. The root elongation of wild watermelon was promoted under the drought stress. In comparison to domesticated watermelon, wild watermelon showed lower sensitivity to exogeneous ABA in the elongation of primary root and the lateral root initiation. CLRAN was expressed mainly in root meristematic and elongation zones, and the expression was increased to 1.5-fold in root tips by drought stress. The Arabidopsis overexpressing CLRAN showed suppressed ABA sensitivity. These results indicate that wild watermelon plants have the root development system for drought avoidance response in which CLRAN functions as a key-regulator.
