| Autor: |
Uzilday B; Department of Biology, Faculty of Science, Ege University, Bornova 35100, Izmir, Turkey., Takahashi K; Graduate School of Life Sciences, Tohoku University, Katahira, Sendai 980-8577, Japan., Kobayashi A; Graduate School of Life Sciences, Tohoku University, Katahira, Sendai 980-8577, Japan., Uzilday RO; Department of Biology, Faculty of Science, Ege University, Bornova 35100, Izmir, Turkey., Fujii N; Graduate School of Life Sciences, Tohoku University, Katahira, Sendai 980-8577, Japan., Takahashi H; Graduate School of Life Sciences, Tohoku University, Katahira, Sendai 980-8577, Japan.; Research Center for Space Agriculture and Horticulture, Graduate School of Horticulture, Chiba University, Matsudo, Chiba 271-8510, Japan., Turkan I; Department of Biology, Faculty of Science, Ege University, Bornova 35100, Izmir, Turkey.; Graduate School of Life Sciences, Tohoku University, Katahira, Sendai 980-8577, Japan.; Faculty of Agricultural Sciences and Technologies, Yasar University, University Street, No. 37-39, Bornova 35100, Izmir, Turkey. |
| Abstrakt: |
Plant roots exert hydrotropism in response to moisture gradients to avoid drought stress. The regulatory mechanism underlying hydrotropism involves novel regulators such as MIZ1 and GNOM/MIZ2 as well as abscisic acid (ABA), reactive oxygen species (ROS), and Ca 2+ signaling. ABA, ROS, and Ca 2+ signaling are also involved in plant responses to drought stress. Although the mechanism of moisture gradient perception remains largely unknown, the sensory apparatus has been reported to reside in the root elongation zone rather than in the root cap. In Arabidopsis roots, hydrotropism is mediated by the action of MIZ1 and ABA in the cortex of the elongation zone, the accumulation of ROS at the root curvature, and the variation in the cytosolic Ca 2+ concentration in the entire root tip including the root cap and stele of the elongation zone. Moreover, root exposure to moisture gradients has been proposed to cause asymmetric ABA distribution or Ca 2+ signaling, leading to the induction of the hydrotropic response. A comprehensive and detailed analysis of hydrotropism regulators and their signaling network in relation to the tissues required for their function is apparently crucial for understanding the mechanisms unique to root hydrotropism. Here, referring to studies on plant responses to drought stress, we summarize the recent findings relating to the role of ABA, ROS, and Ca 2+ signaling in hydrotropism, discuss their functional sites and plausible networks, and raise some questions that need to be answered in future studies. |
