Brassinosteroid‐Promoted Growth

Abstract

Brassinosteroids (BRs) are highly potent growth-promoting sterol derivatives. BR-deficient or BR-insensitive mutants display dwarfism. Whole plants and excised tissues have been used to analyse the mechanisms involved in BR-promoted growth. BR stimulates cell elongation and cell division, and BR has specific effects on differentiation. Underlying physiological pathways include modification of cell wall properties, effects on carbohydrate assimilation and allocation, and control of aquaporin activities. BR apparently coordinates and integrates diverse processes required for growth, partly via interactions with other phytohormones setting the frame for BR responses. Ultimately, BR-promoted growth is mediated through genomic pathways. Positive regulators of the BR response (such as BZR1 and BES1) and putative downstream components (such as EXO) are involved in the regulation of BR-responsive genes and growth promotion. BR-responsive genes have been identified in several plant species. However, causal links between physiological effects and changes of transcript patterns, for the most part, are still unresolved. This review focuses on physiology and molecular mechanisms underlying BR-promoted growth in the different plant organs. Interactions with other phytohormones are discussed.

Steroids are required for epidermal cell fate establishment in Arabidopsis roots

“…A recent study has demonstrated that auxin transport through the nonhair cells controls the elongation of root hairs in the hair cell position (10). Global transcriptome analysis of whole seedlings revealed that expression of WER can be induced by treatment with brassinosteroids (BRs) (11), a class of steroid hormones known to promote growth in diverse plant species (12). Although BRs are known to affect root elongation (13), no previous work has connected them to the root hair formation program.…”

Effects of a brassinosteroid and an ecdysone analogue on pollen germination of rice under heat stress

“…21) BRs may also affect fertilization by stimulating filament and pollen growth and modifying pollen properties. 22) Sheoran and Saini reported that normal starch accumulation during pollen development was strongly inhibited in stressful environments and caused nonviable pollen.…”

Tracing a key player in the regulation of plant architecture: the columnar growth habit of apple trees (Malus × domestica)

“…Elongation growth is mainly mediated via gibberellins (GAs) and brassinosteroids (BRs) (reviewed in Phinney 1985;Müssig 2005), which stimulate internode elongation (Yamamuro et al 2000;Dayan et al 2012;Li et al 2012). Ethylene signaling has been shown to influence internode elongation in rice adapted to deep water conditions (Hattori et al 2009;Qi et al 2011), and IAA contributes to elongation growth in pea (McKay et al 1994).…”