The existence of different auxin sensitivities in epidermal and subepidermal tissues (KV Thimann, CL Schneider 1938 Plant Physiol 25: 627-641) suggests a refinement to the Cholodny-Went theory which overcomes some of the difficulties associated with it. A model is presented to account for the inverse tropic responses of shoots and roots through differences in the respective locations of the auxin-sensitive tissues.
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http://dx.doi.org/10.1104/pp.84.3.568 | DOI Listing |
Plants (Basel)
January 2021
Department of Agricultural Sciences, University of Naples Federico II, Via Università 100, 80055 Portici, Italy.
Tropisms are essential responses of plants, orienting growth according to a wide range of stimuli. Recently, considerable attention has been paid to root tropisms, not only to improve cultivation systems, such as those developed for plant-based life support systems for future space programs, but also to increase the efficiency of root apparatus in water and nutrient uptake in crops on Earth. To date, the Cholodny-Went theory of differential auxin distribution remains the principal tropistic mechanism, but recent findings suggest that it is not generally applicable to all root tropisms, and new molecular pathways are under discussion.
View Article and Find Full Text PDFFront Plant Sci
February 2020
Department of Agricultural Sciences, University of Naples Federico II, Naples, Italy.
Root tropisms are important responses of plants, allowing them to adapt their growth direction. Research on plant tropisms is indispensable for future space programs that envisage plant-based life support systems for long-term missions and planet colonization. Root tropisms encompass responses toward or away from different environmental stimuli, with an underexplored level of mechanistic divergence.
View Article and Find Full Text PDFPlant Sci
November 2016
Department of Molecular Biology & Ecology of Plants, Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 69978 Israel. Electronic address:
Optimization of water foraging by plants is partially achieved by the ability of roots to direct growth towards high water potential, a phenomenon termed hydrotropism. In contrast to gravitropism and phototropism, which require auxin redistribution, as suggested by the Cholodny-Went theory, hydrotropism is not mediated by the phytohormone auxin, which raises questions about the mechanism underlying this tropic response. Here we specify the open questions in this field of research and discuss the possible interactions of abscisic acid, calcium and reactive oxygen species as part of a dynamic system of sensing water potential in the root tip, transmission of the signal to the root elongation zone and promoting root curvature towards water.
View Article and Find Full Text PDFFront Plant Sci
October 2015
Salk Institute for Biological Studies , La Jolla, CA, USA ; Howard Hughes Medical Institute, La Jolla, USA.
Despite their sessile lifestyle, seed plants are able to utilize differential growth rates to move their organs in response to their environment. Asymmetrical growth is the cause for the formation and maintenance of the apical hook-a structure of dicotyledonous plants shaped by the bended hypocotyl that eases the penetration through the covering soil. As predicted by the Cholodny-Went theory, the cause for differential growth is the unequal distribution of the phytohormone auxin.
View Article and Find Full Text PDFPlant Mol Biol
March 2009
Graduate School of Life Sciences, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
Terrestrial plants have evolved remarkable morphological plasticity that enables them to adapt to their surroundings. One of the most important traits that plants have acquired is the ability to sense environmental cues and use them as a basis for governing their growth orientation. The directional growth of plant organs relative to the direction of environmental stimuli is a tropism.
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