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ETILENO. Fig. 2. Arabidopsis thaliana wild-type and cabbage mutants. From left to right: wild type, cbb1 (dwf1–6), cbb2 and cbb3, all three weeks old and grown in half-concentrated MS
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Fig. 2. Arabidopsis thaliana wild-type and cabbage mutants. From left to right: wild type, cbb1 (dwf1–6), cbb2 and cbb3, all three weeks old and grown in half-concentrated MS (Murashige and Skoog) medium. The cbb1 and cbb3 mutants are brassinosteroid-deficient owing to defects in the biosynthetic genes DIM and CPD, respectively 50,51 . The cbb2 mutant is allelic to the bri1/bin mutants and brassinosteroid-insensitive. The affected gene (BRI1) encodes a plasma-membrane Ser/Thr receptor-like kinase.
Fig. 1. Structural formulas of plant and animal steroid hormones. (a) Cholesterol, the precursor of all steroid hormones in animals; (b) testosterone, a sex hormone in vertebrates; (c) 20-hydroxyecdysone, a moulting hormone from insects; (d) brassinolide, the most active brassinosteroid from plants. Sites of structural variation between various brassinosteroids are highlighted (red) in the brassinolide formula.