Abstract
Arabidopsis leaf morphology is determined by the coordinated action of cell division and elongation. Of all the hormones that control leaf shape, the brassinosteroids (BRs) are active components in this process. BRs are a group of plant-originated steroidal compounds that induce growth along the long axes of organs. Here, we report the isolation and characterization of a novel mutant,short root and dwarfism (srd). Its dwarf phenotype includes round and curled leaves, reduced fertility, and short hypocotyls in the light and dark. Dwarfism in the aerial portions and a short-root morphology are not rescued by exogenous application of BRs, suggesting thatsrd is not impaired in BR metabolic pathways. Anatomical analysis revealed thatsrd roots are much shorter and thicker than the wild type due to additional layers of cortical cells. A lack of cell elongation but an increase in division results in these short but horizontally swollen roots. A double mutantsrd/bri1-5 also displays the short-root phenotype, implying thatsrd is epistatic tobri1. Cloning and further characterization ofSRD should provide additional information about its role in the determination of leaf shape and root elongation.
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Literature cited
Bishop GJ (2003) Brassinosteroid mutants of crops. J Plant Growth Regul22: 325–335
Choe S (2004) Brassinosteroid biosynthesis and metabolism,In Davies PJ, ed, Plant Hormones: Biosynthesis, Signal Transduction, Action! Springer, New York, pp 156–178
Choe S, Dilkes BP, Gregory BD, Ross AS, Yuan H, Noguchi T, Fujioka S, Takatsuto S, Tanaka A, Yoshida S, Tax F, Feldmann KA (1999a)Arabidopsis dwarf1 mutant is defective in the conversion of 24-rnethylenecholesterol to campesterol in brassinosteroid biosynthesis. Plant Physiol119: 897–907
Choe S, Fujioka S, Noguchi T, Takatsuto S, Yoshida S, Feldmann KA (2001) Overexpression of DWARF4 in the brassinosteroid biosynthetic pathway results in increased vegetative growth and seed yield inArabidopsis. Plant J26: 573–582
Choe S, Noguchi T, Fujioka S, Takatsuto S, Tissier CP, Gregory BD, Ross AS, Tanaka A, Yoshida S, Tax FE, Feldmann KA (1999b) TheArabidopsis dwf7/ste 1 mutant is defective in the D7 sterol C-5 desaturation step leading to brassinosteroid biosynthesis. Plant Cell11: 207–221
Choe S, Schmitz RJ, Fujioka S, Takatsuto S, Lee MO, Yoshida S, Feldmann, KA, Tax FE (2002)Arabidopsis brassinosteroid-insensitivedwarf12 mutants are semidominant and defective in a glycogen synthase kinase 3 β-like kinase. Plant Physiol130: 1506–1515
Fujioka S, Takatsuto S, Yoshida S (2002) An early C-22 oxidation branch in the brassinosteroid biosynthetic pathway. Plant Physiol130: 930–939
He JX, Gendron JM, Sun Y, Gampala SS, Gendron N, Sun CQ, Wang ZY (2005) BZR1 is a transcriptional repressor with dual roles in brassinosteroid homeostasis and growth responses. Science307: 1634–1638
Hu Y, Bao F, Li J (2000) Promotive effect of brassinosteroids on cell division involves a distinct CycDS-induction pathway inArabidopsis. Plant J24: 693–701
Kauschmann A, Jessop A, Koncz C, Szekeres M, Willmitzer L, Altmann T (1996) Genetic evidence for an essential role of brassinosteroids in plant development. Plant J9: 701–713
Kim GT, Fujioka S, Kozuka T, Tax FE, Takatsuto S, Yoshida S, Tsukaya H (2005) CYP90C1 and CYP90D1 are involved in different steps in the brassinosteroid biosynthesis pathway inArabidopsis thaliana. Plant J41: 710–721
Kim GT, Tsukaya H, Uchimiya H (1998) TheROTUN-DIFOLIA3 gene ofArabidopsis thaliana encodes a new member of the cytochrome P-450 family that is required for the regulated polar elongation of leaf cells. Genes Dev12: 2381–2391
Kwon M, Choe S (2005) Brassinosteroid biosynthesis and dwarf mutants. J Plant Biol48: 1–15
Li J, Chory J (1997) A putative leucine-rich repeat receptor kinase involved in brassinosteroid signal transduction. Cell90: 929–938
Li J, Nam KH, Vafeados D, Chory J (2001) BIN2, a new brassinosteroid-insensitive locus inArabidopsis. Plant Physiol127: 14–22
Li J, Wen J, Lease KA, Doke JT, Tax FE, Walker JC (2002) BAK1, anArabidopsis LRR receptor-like protein kinase, interacts with BRI1 and modulates brassinosteroid signaling. Cell110: 213–222
Noguchi T, Fujioka S, Choe S, Takatsuto S, Yoshida S, Yuan H, Feldmann KA, Tax FE (1999) Brassinosteroid-insensitive dwarf mutantsof Arabidopsis accumulate brassinosteroids. Plant Physiol121: 743–752
Perez-Perez JM, Ponce MR, Micol JL (2002) The UCU1Arabidopsis gene encodes a SHAGGY/GSK3-like kinase required for cell expansion along the proximodistal axis. Dev Biol242: 161–173
Sasse JM (2003) Physiological actions of brassinosteroids: An update. J Plant Growth Regul22: 276–288
Wang ZY, Nakano T, Gendron J, He J, Chen M, Vafeados D, Yang Y, Fujioka S, Yoshida S, Asami T, Chory J (2002) Nuclear-localized BZR1 mediates brassinoster-oid-induced growth and feedback suppression of brassinosteroid biosynthesis. Dev Cell2: 505–513
Yin Y, Cheong H, Friedrichsen D, Zhao Y, Hu J, Mora-Gar-cia S, Chory J (2002) A crucial role for the putativeArabidopsis topoisomerase VI in plant growth and development. Proc Natl Acad Sci USA99: 10191–10196
Yin Y, Vafeados D, Tao Y, Yoshida S, Asami T, Chory J (2005) A new class of transcription factors mediates brassinosteroid-regulated gene expression inArabidopsis. Cell120: 249–259
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Lee, H.K., Kwon, M., Jeon, J.H. et al. AnArabidopsis short root and dwarfism mutant defines a novel locus that mediates both cell division and elongation. J. Plant Biol. 49, 61–69 (2006). https://doi.org/10.1007/BF03030789
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DOI: https://doi.org/10.1007/BF03030789