phyB is evolutionarily conserved and constitutively expressed in rice seedling shoots
K Dehesh1, J Tepperman, A H Christensen
1University of California, Berkeley.
Molecular & General Genetics : MGG
|February 1, 1991
Summary
Rice genome analysis reveals single copies of phyA and phyB genes. PhyB shows closer relation to Arabidopsis phyB than rice phyA, suggesting early subfamily divergence and slower phyB evolution.
Area of Science:
- Plant molecular biology
- Genetics
- Evolutionary biology
Background:
- Phytochromes (phyA and phyB) are crucial photoreceptors in plants.
- Understanding their evolutionary divergence and gene regulation is key to plant development.
Purpose of the Study:
- To investigate the rice phytochrome genes (phyA and phyB) and their evolutionary relationship with Arabidopsis.
- To analyze the gene expression patterns of phyA and phyB in rice.
Main Methods:
- Southern blot analysis to determine gene copy number.
- Isolation of cDNA and genomic clones for phyB.
- Amino acid sequence comparison between rice and Arabidopsis phytochromes.
- Northern blot analysis for gene expression studies.
Main Results:
- Rice genome contains single copies of phyA and phyB genes.
- Rice phyB is more closely related to Arabidopsis phyB than to rice phyA, indicating early divergence.
- PhyB appears to have evolved more slowly than phyA.
- PhyA is negatively regulated by light in rice shoots, while phyB is constitutively expressed.
- Both phyA and phyB transcripts are abundant in green tissue.
Conclusions:
- PhyA and phyB subfamilies diverged early in plant evolution, with subsequent divergence between monocots and dicots.
- PhyB exhibits conserved, light-independent expression across monocots and dicots, suggesting a conserved functional role.
- The differential regulation of phyA and phyB may reflect distinct functional roles within the phytochrome family.
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