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Title: COORDINATION OF PHYTOCHROME LEVELS IN PHYB MUTANTS OF ARABIDOPSIS AS REVEALED BY APOPROTEIN-SPECIFIC MONOCLONAL ANTIBODIES

Author
item HIRSCHFELD, MATTHEW - MONTANA STATE UNIV
item TEPPERMAN, JAMES - USDA/UCB PGEC
item CLACK, TED - MONTANA STATE UNIV
item QUAIL, PETER - USDA/UCB PGEC
item SHARROCK, ROBERT - MONTAN STATEUNIV

Submitted to: Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/1998
Publication Date: N/A
Citation: Hirschfeld, M., Tepperman, J.M., Clack, T., Quail, P.H., Sharrock, R.A. 1998. Coordination of Phytochrome Levels in phyB Mutants of Arabidopsis as Revealed by Apoprotein-Specific Monoclonal Antibodies. Genetics 149:523-535.

Interpretive Summary: Accumulating evidence indicates that individual members of the Chytochrome family of photoreceptors have differential but interactive roles in controlling plant responses to light. These observations indicate that molecular mechanisms for coordination or crossregulation of phytochrome levels are active in Arabidopsis and have implications for the interpretation of phytochrome mutants and overexpressor lines.

Technical Abstract: Accumulating evidence indicates that individual members of the hytochrome family of photoreceptors have differential but interactive roles in controlling plant responses to light. To investigate possible crossregulation of these receptors, we have identified monoclonal antibodies that specifically detect each of the five Arabidopsis phytochromes, phyA to phyE phytochrome A holoprotein; PHYA, phytochrome A apoprotein; PHYA, phytochrome A gene; phyA, mutant allele of phytochrome A gene, on immunoblots and have used them to analyze the effects of phyA and phyB null mutations on the levels of all five family members. In phyB mutants, but not in phyA mutants, a four to sixfold reduction in the level of phyC is observed in tissues grown either in the dark or in the light. Coordinate expression of phyB and phyC is induced in the phyB mutant background by the presence of a complementing PHYB transgene. However, in transgenic lines that overexpress phyB 15 to 20fold, phyC is not similarly overexpressed. In these overexpressor lines, the levels of phyA, phyC, and phyD are increased two to fourfold over normal in lightgrown but not darkgrown seedlings. These observations indicate that molecular mechanisms for coordination or crossregulation of phytochrome levels are active in Arabidopsis and have implications for the interpretation of phytochrome mutants and overexpressor lines.