title: Genetic identification of ACC-RESISTANT2 reveals involvement of LYSINE HISTIDINE TRANSPORTER1 in the uptake of 1-aminocyclopropane-1-carboxylic acid in Arabidopsis thaliana.
abstract: 1-Aminocyclopropane-1-carboxylic acid (ACC) is a biosynthetic precursor of ethylene, a gaseous plant hormone which controls a myriad of aspects of development and stress adaptation in higher plants. Here, we identified a mutant in Arabidopsis thaliana, designated as ACC-resistant2 (are2), displaying a dose-dependent resistance to exogenously applied ACC. Physiological analyses revealed that mutation of are2 impaired various aspects of exogenous ACC-induced ethylene responses, while not affecting sensitivity to other plant hormones during seedling development. Interestingly, the are2 mutant was normally sensitive to gaseous ethylene, compared with the wild type. Double mutant analysis showed that the ethylene-overproducing mutations, eto1 or eto3, and the constitutive ethylene signaling mutation, ctr1 were epistatic to the are2 mutation. These results suggest that the are2 mutant is not defective in ethylene biosynthesis or ethylene signaling per se. Map-based cloning of ARE2 demonstrated that LYSINE HISTIDINE TRANSPORTER1 (LHT1), encoding an amino acid transporter, is the gene responsible. An uptake experiment with radiolabeled ACC indicated that mutations of LHT1 reduced, albeit not completely, uptake of ACC. Further, we performed an amino acid competition assay and found that two amino acids, alanine and glycine, known as substrates of LHT1, could suppress the ACC-induced triple response in a LHT1-dependent way. Taken together, these results provide the first molecular genetic evidence supporting that a class of amino acid transporters including LHT1 takes part in transport of ACC, thereby influencing exogenous ACC-induced ethylene responses in A. thaliana.
authors.affiliation: Department of Molecular Biology, College of Life Science, Sejong University, Seoul, Republic of Korea.
authors.forename: Kihye
authors.initials: K
authors.lastname: Shin
authors.affiliation: Department of Molecular Biology, College of Life Science, Sejong University, Seoul, Republic of Korea.
authors.forename: Sumin
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Life Science, Pohang University of Science and Technology, Pohang, Republic of Korea.
authors.forename: Won-Yong
authors.initials: WY
authors.lastname: Song
authors.affiliation: Department of Molecular Biology, College of Life Science, Sejong University, Seoul, Republic of Korea.
authors.forename: Rin-A
authors.initials: RA
authors.lastname: Lee
authors.affiliation: Department of Molecular Biology, College of Life Science, Sejong University, Seoul, Republic of Korea.
authors.forename: Inhye
authors.initials: I
authors.lastname: Lee
authors.affiliation: Department of Molecular Biology, College of Life Science, Sejong University, Seoul, Republic of Korea.
authors.forename: Kyungsun
authors.initials: K
authors.lastname: Ha
authors.affiliation: Division of Science Education and Institute of Science Education, Chonbuk National University, Jeonju, Republic of Korea.
authors.forename: Ja-Choon
authors.initials: JC
authors.lastname: Koo
authors.affiliation: Center for Plant Aging Research, Institute for Basic Science, and School of Applied Biosciences, Kyungpook National University, Daegu, Republic of Korea.
authors.forename: Soon-Ki
authors.initials: SK
authors.lastname: Park
authors.affiliation: Center for Plant Aging Research, Institute for Basic Science, and Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology, Daegu, Republic of Korea.
authors.forename: Hong-Gil
authors.initials: HG
authors.lastname: Nam
authors.affiliation: Department of Life Science, Pohang University of Science and Technology, Pohang, Republic of Korea.
authors.forename: Youngsook
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Department of Molecular Biology, College of Life Science, Sejong University, Seoul, Republic of Korea soh@sejong.ac.kr.
authors.forename: Moon-Soo
authors.initials: MS
authors.lastname: Soh
mesh_terms: D000483:Alleles; D026923:Amino Acid Transport Systems, Basic / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism; D000598:Amino Acids, Cyclic / Q000378:metabolism*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004843:Epistasis, Genetic / Q000187:drug effects; D005030:Ethylenes / Q000378:metabolism / Q000494:pharmacology; D009154:Mutation
chemical_list: D026923:Amino Acid Transport Systems, Basic; D000596:Amino Acids; D000598:Amino Acids, Cyclic; D029681:Arabidopsis Proteins; D002250:Carbon Radioisotopes; D005030:Ethylenes; C110638:LHT1 protein, Arabidopsis; C023863:1-aminocyclopropane-1-carboxylic acid; C036216:ethylene
keywords: ACC uptake; Arabidopsis thaliana; Ethylene; LHT1; Triple response