Lu YT, Feldman LJ.
ASGSB Bull. 1995 Oct; 9: 80.
Department of Plant Biology, University of California, Berkeley, USA.
Light regulates many aspects of plant growth and development, yet relatively little is known about the steps involved in transducing the light signal into a developmental response. A model system for studying light signal transduction is shown by roots of certain cultivars of corn which respond to gravity only if illuminated. This light-regulated root gravitropism involves phytochrome and is mediated by calcium, but very little more is known about how light and gravity interact to bring about gravitropic root bending. Towards further characterizing this interaction we have isolated two isomers of calcium/calmodulin-dependent protein kinases (both cDNAs and genomic DNAs) from Zea mays (cv. Merit) root caps, the site for both gravity and light perception in roots. Sequencing analyses show that these isomers have over 90% identity in amino acid sequence, and both contain kinase catalytic and calmodulin-binding domains. Though their expressions appear to be differentially regulated, both isomers have similar genomic structures. Further analyses indicate that the E.coli-expressed fusion protein binds to calmodulin (CaM) in a calcium-dependent manner. However, this binding is abolished in the presence of inhibitors (KN-93) of animal CaM kinase II. Interestingly, this light-regulated root gravitropism is also inhibited by this drug. We have previously shown that KN-93 acts by interrupting light signal transduction, suggesting that light-regulated root gravitropism may involve a CaM kinase in signal transduction. Further studies of a role of CaM kinases in root gravitropism will involve regulation of expression, substrate identification and analysis of transgenic plants.
Publication Types:
Keywords:
- Amino Acid Sequence
- Benzylamines
- Calcium
- Calcium-Calmodulin-Dependent Protein Kinase Type 2
- Calcium-Calmodulin-Dependent Protein Kinases
- Calmodulin
- Gravitation
- Gravitropism
- KN 93
- Light
- Phytochrome
- Plant Roots
- Signal Transduction
- Zea mays
- NASA Discipline Number 40-50
- NASA Discipline Plant Biology
- NASA Program Space Biology
- Non-NASA Center
Other ID:
UI: 102222705
From Meeting Abstracts