A critical role of sterols in embryonic patterning and meristem programming revealed by the fackel mutants of Arabidopsis thaliana |
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Authors: | Jang J C Fujioka S Tasaka M Seto H Takatsuto S Ishii A Aida M Yoshida S Sheen J |
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Affiliation: | Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio 43210 USA. |
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Abstract: | Here we report a novel Arabidopsis dwarf mutant, fackel-J79, whose adult morphology resembles that of brassinosteroid-deficient mutants but also displays distorted embryos, supernumerary cotyledons, multiple shoot meristems, and stunted roots. We cloned the FACKEL gene and found that it encodes a protein with sequence similarity to both the human sterol reductase family and yeast C-14 sterol reductase and is preferentially expressed in actively growing cells. Biochemical analysis indicates that the fk-J79 mutation results in deficient C-14 sterol reductase activity, abnormal sterol composition, and reduction of brassinosteroids (BRs). Unlike other BR-deficient mutants, the defect of hypocotyl elongation in fk-J79 cannot be corrected by exogenous BRs. The unique phenotypes and sterol composition in fk-J79 indicate crucial roles of sterol regulation and signaling in cell division and cell expansion in embryonic and post-embryonic development in plants. |
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