Compositions, Cells, and Plants that Include BK11, A Negative Regulator of BRI1-Mediated BR Signaling
Inventors: Xuelu Wang, Joanne Chory
Potential Uses: Plant Biology, Growth and Yield
The BRI1 gene encodes a receptor serine/threonine kinase. Loss-of-function mutations in BRI1 result in dwarf plants that resemble steroid-deficient plants.
Earlier studies provided evidence that the action of a steroid hormone, brassinolide (BL), may be involved in light-regulated gene expression and cell elongation responses in plants. BL-deficient plants display many defects throughout development. In the dark, these mutants develop as light-grown plants and inappropriately express light-regulated genes. In the light, BL-deficient mutants are dwarfs, have reduced male fertility, and display a significant delay in the senescence program. In the absence of hormone, Arabidopsis plants do not respond properly to fluctuations in their light environment.
The inventors have dicovered mutations in a gene, BRI1, that encodes a receptor serine/threonine kinase. Loss-of-function mutations in BRI1 result in dwarf plants that resemble steroid-deficient plants. Using a photoaffinity-labeled ligand, it was shown that BRI1 binds BL directly through a 94-amino acid region that includes the 70-amino acid subdomain in the extracellular domain. Moreover, BRI1 functions as a homodimer and in close proximity with BAK1, a second LRR-kinase. BRI1 is kept in a basal state by BKI1, a negative regulator whose function is to prevent the interaction of BRI1 with BAK1 in the absence of ligand.
Other studies, using full-genome microarrays, indicate that BL and another plant hormone, auxin, regulate the expression of scores of overlapping target genes, and that the two signaling pathways act in close proximity, especially in terms of growth responses regulated by light.
Patent Status: U.S. Patent Application published as US-2009/0013433 A1
Publications: The Plant Cell, Vol. 19 1709-1717 May 2007
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