Arabidopsis Hexokinase-Like1 and Hexokinase1 Form a Critical Node in Mediating Plant Glucose and Ethylene Responses

Journal Article · Sun Jan 01 04:00:00 EST 2012 · Plant Physiology

DOI:https://doi.org/10.1104/pp.112.195636· OSTI ID:1042786

Karve, Abhijit A ^[1]; Xioxia, Xia ^[2]; Moore, Brandon ^[2]

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1. ORNL
2. Clemson University

Arabidopsis (Arabidopsis thaliana) hexokinase-like1 (HKL1) lacks Glc phosphorylation activity and has been shown to act as a negative regulator of plant growth. Interestingly, the protein has a largely conserved Glc binding domain and protein overexpression was shown previously to promote seedling tolerance to exogenous 6% (w/v) Glc. Since these phenotypes occur independently of cellular Glc signaling activities, we have tested whether HKL1 might promote crosstalk between the normal antagonists Glc and ethylene. We show that repression by 1-aminocyclopropane-1-carboxylic acid (ACC) of the Glc-dependent developmental arrest of wild-type Arabidopsis seedlings requires the HKL1 protein. We also describe an unusual root hair phenotype associated with growth on high Glc media that occurs prominently in HKL1 overexpression lines and in gin2-1, a null mutant of hexokinase1 (HXK1). Seedlings of these lines produce bulbous root hairs with an enlarged base, after transfer from agar plates with normal media to plates with 6% Glc. Seedling transfer to plates with 2% Glc plus ACC mimics the high Glc affect in the HKL1 overexpression line, but not in gin2-1. A similar ACC-stimulated, bulbous root hair phenotype also was observed in wild-type seedlings transferred to plates with 9% Glc. From transcript expression analyses, we found that HKL1 and HXK1 have differential roles in Glc-dependent repression of some ethylene biosynthesis genes. Since we show by co-immunoprecipitation assays that HKL1 and HXK1 can interact, these two proteins likely form a critical node in Glc signaling that mediates overlapping, but also distinct cellular responses to Glc and ethylene treatments.

• Research Organization: Oak Ridge National Laboratory (ORNL)
• Sponsoring Organization: ORNL LDRD Director's R&D
• DOE Contract Number: AC05-00OR22725
• OSTI ID: 1042786
• Journal Information: Plant Physiology, Journal Name: Plant Physiology Journal Issue: 4 Vol. 158; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
60 APPLIED LIFE SCIENCES
ARABIDOPSIS
BIOSYNTHESIS
ETHYLENE
GENES
GLUCOSE
HAIR
MUTANTS
PHENOTYPE
PHOSPHORYLATION
PLANT GROWTH
PLATES
PROTEINS
SEEDLINGS
TOLERANCE