Abstract
Root hydrotropism plays an important role in plant escape from water stress, but its molecular mechanism is not understood. We established an experimental system for the study of hydrotropism in Arabidopsis roots and successfully isolated 14 hydrotropism mutants named root hydrotropism (rhy). We have characterized some of those mutants; namely, rhy1 is defective in hydrotropism, but its gravitropism, phototropism, waving response and elongation growth are similar to those of the wild type. Roots of rhy2 and rhy3 display abnormal hydrotropism together with altered waving response, gravitropism and/or phototropism. Here, we report that rhy4 and rhy5 roots lack positive hydrotropism at all. Interestingly, rhy4 roots show negative hydrotropism curving away from the water source and reduced amplitude in waving response. Roots of rhy5 show reduced elongation growth during the waving response. Furthermore, mutations of rhy1 and rhy4 were mapped to different chromosomes.
