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KMID : 0613820180280010009
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Journal of Life Science
2018 Volume.28 No. 1 p.9 ~ p.16
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Phytochromes are Involved in the Regulation of Growth and the Gravitropic Response via Ethylene Production in Hypocotyl of Arabidopsis
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Lee Sang-Seung
Kim Soon-Young
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Abstract
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Light is essential to the growth and development of plants, and it is perceived by phytochromes, which are one of the photoreceptors that regulate physiological responses in plants. Ethylene regulates the dormancy, senescence, growth, and development of organs in plants. This research focused on the interaction of phytochromes and ethylene to control hypocotyl growth and gravitropism using phytochrome mutants of Arabidopsis, phyA, phyB, and phyAB, under three light conditions: red (R) light, far- red (FR) light, and white light. The mutant phyAB exhibited the most stimulation of gravitropic response of all three phytochrome mutants and wild type (WT) in all three light conditions. Moreover, phyB in the R light condition showed more negative gravitropism than phyA. However, phyB in the FR light condition showed less curvature than phyA. The hypocotyl growth pattern was similar to the gravitropic response in several light conditions. To explain the mechanism of the regulation of gravitropic response and growth, we measured the ethylene production and activities of in vitro ACS and ACO. Ethylene production was reduced in all the mutants grown in white light in comparison to the WT. Ethylene production increased in the phyA grown in R light and phyB grown in FR light in comparison to the other mutants. The ACS activity coincided with the ethylene production in the phyA and the phyB grown in R light and FR light, respectively. These results suggest that the Pfr form of phyB in R light and the Pr form of phyA in FR light increased ethylene production via increasing ACS activity.
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KEYWORD
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Arabidopsis, ethylene, gravitropic response, hypocotyl, phytochrome mutant
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