About the Cover
Phytohormones, in combination with light, have a profound effect on cell elongation and, therefore, plant size. However, little is known about the molecular basis for the dwarfism that results from defects in these various signaling pathways. On pages 219-230 of this issue, Azpiroz et al. present evidence from their own analyses of the Arabidopsis dwf4 mutant that brassinosteroids (BRs) operate downstream of signals from other phytohormones and light to control cell elongation. And on pages 231-243, Choe et al. show that DWF4, a cytochrome P450, mediates multiple 22
-hydroxylation steps during BR biosynthesis. This conculsion is drawn in part from the feeding studies depicted on the cover, which shows, from left to right, the infloresences of dwf4 plants that have been treated with the BR biosynthetic intermediates 6-oxocampestanol, cathasterone, and 6-deoxycathasterone. Only the latter two intermediates, which are hydroxylated at the C-22 position, are capable of restoring the wild-type phenotype of dwf4 plants.
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Copyright © 2007 by the American Society of Plant Biologists
