Hormone Signalling Crosstalk in Plant Growth Regulation

Abstract

The remarkable plasticity of plant ontogeny is shaped by hormone pathways, which not only orchestrate intrinsic developmental programs, but also convey environmental inputs. Several classes of plant hormones exist, and among them auxin, brassinosteroid and gibberellin are central for the regulation of growth in general and of cell elongation in particular. Various growth phenomena can be modulated by each of the three hormones, in a sometimes synergistic fashion, suggesting physiological redundancy and/or crosstalk between the different pathways. Whether this means that they target a common and unique transcriptome module, or rather separate growth-promoting transcriptome modules, remains unclear, however. Nevertheless, while surprisingly few molecular mediators of direct crosstalk in the proper sense have been isolated, evidence is accumulating for complex cross-regulatory relations between hormone pathways at the level of transcription, as exemplified in root meristem growth. The growing number of available genome sequences from the green lineage offers first glimpses at the evolution of hormone pathways, which can aid in understanding the multiple relationships observed between these pathways in angiosperms. The available analyses suggest that auxin, gibberellin and brassinosteroid signalling arose during land plant evolution in this order, correlating with increased morphological complexity and possibly conferring increased developmental flexibility.

RootScape: A Landmark-Based System for Rapid Screening of Root Architecture in Arabidopsis

“…4). For example, as reported previously (Hobbie and Estelle, 1995;Depuydt and Hardtke, 2011) and shown by ANOVA above, the change of root plasticity of axr4 (Fig. 4B) compared with the wild type (Fig.…”

“…Using RootScape to Characterize the Plasticity of RSA Different phytohormones are known to exert specific effects on root architecture, with partially overlapping effects often due to cross talk between hormones (Bishopp et al, 2011; for review, see Depuydt and Hardtke, 2011). We used RootScape to characterize the plasticity of the Arabidopsis root system under hormone treatments.…”

Molecular genetic framework for protophloem formation

“…4 E and F), suggesting it is particularly sensitive to changes in auxin activity. Given that BRX has been implicated in potentiating auxin response (11,24), this would also explain why the penetrance of the observed phenotypes was highest in brx mutants. Remarkably, however, root growth rate and meristem size were only mildly impaired in auxinole-treated roots, despite the absence of the incipient metaphloem cell file (Fig.…”

Response to metal stress of Nicotiana langsdorffii plants wild-type and transgenic for the rat glucocorticoid receptor gene

“…Brassinosteroids have been shown to induce tolerance to a wide range of abiotic stresses (Kagale et al, 2007;Bajguz, 2011;Sittayat et al, 2007;Arora et al, 2010a;Koh et al, 2007) through the activation of anti-oxidative stress systems (Arora et al, 2010b), as well as the enhanced synthesis of abscisic acid (Yuan et al, 2010), ethylene, salicylic acid (Divi et al, 2010), polyamines and indole-3-acetic acid (Choudhary et al, 2010(Choudhary et al, , 2011. Responses to stress in plants, moreover, are known to be activated by increased levels of auxins, which in turn determines feedback interaction with flavonoid synthetic patterns (Peer and Murphy, 2007;Lewis et al, 2011) and crosstalk with brassinosteroid transcription process (see Depuydt and Hardtke (2011) for an extensive review).…”