Exogenous Glutamate Inhibits the Root Growth and Increases the Glutamine Content in <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> |
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Authors: | Ta Hee Kim Eui Cheol Kim Suk Weon Kim Hyo Shin Lee Dong-Woog Choi |
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Institution: | (1) Department of Biology Education, Chonnam National University, Kwangju, 500-757, South Korea;(2) Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejon, 305-333, South Korea;(3) Biotechnology division, Korea Forest Research Institute, Suwon, 441-350, South Korea;(4) Kumho Life Science Laboratory, Chonnam National University, Kwangju, 500-757, South Korea; |
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Abstract: | Previously, our work with ginseng hairy root shows that the tissue of low-branching and slow-growing phenotype contains high
level of glutamine. In order to check if the high glutamine concentration inhibits the root growth, we applied exogenous glutamine
or glutamate into growth medium and check the root growth of Arabidopsis. While glutamine did not affect root growth, over 0.1 mM glutamate inhibited severe root growth. However, when the amino
acid solution was adjusted to pH 5.7 and added into medium, Arabidopsis seedlings show normal growth pattern on medium containing glutamate or aspartate. These results demonstrated that inhibition
of the root growth by high concentration of exogenous glutamate was a result of the low pH toxicity caused by acidic amino
acid, although low concentration (0.05 mM) of glutamate has an inhibitory effect on the primary root growth. The application
of exogenous glutamine or glutamate increases glutamine concentration within root tissue about 3- to 4-fold. However, concentration
of glutamate is not significantly increased. The KO mutant on each of the Gln1_1, Gln1_2, or Glu2 gene was little effective on the root growth. These results indicate that high concentration of endogenous glutamine observed
in root tissue does not affect root growth. |
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Keywords: | |
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