Hormonal regulation of the basic peroxidase isoenzyme from Zinnia elegans

Abstract

Xylem differentiation in plants is under strict hormonal regulation. Auxins and cytokinins, together with brassinosteroids (BRs), appear to be the main hormones controlling vascular differentiation. In this report, we study the effect of these hormones on the basic peroxidase isoenzyme from Zinnia elegans (ZePrx), an enzyme involved in lignin biosynthesis. Results showed that auxins and cytokinins induce ZePrx, similarly to the way in which they induce seedling secondary growth (in particular, metaxylem differentiation). Likewise, the exogenous application of BR reduces the levels of ZePrx, in a similar way to their capacity to inhibit seedling secondary growth. Consistent with this notion, the exogenous application of BR reverses the auxin/cytokinin-induced ZePrx expression, but has no effect on the auxin/cytokinin-induced secondary growth. This differential hormonal response is supported by the analysis of the ZePrx promoter, which contains (a) cis-elements directly responsive to these hormones and (b) cis-elements targets of the plethora of transcription factors, such as NAC, MYB, AP2, MADS and class III HD Zip, which are up-regulated during the auxin- and cytokinin-induced secondary growth. Taken together, these results suggest that ZePrx is directly and indirectly regulated by the plethora of hormones that control xylem differentiation, supporting the role of ZePrx in xylem lignification.

Xylogenesis in zinnia (Zinnia elegans) cell cultures: unravelling the regulatory steps in a complex developmental programmed cell death event

“…Treatment of the seedlings with auxin and CK induced ZePrx and metaxylem differentiation during seedling secondary growth whereas the exogenous application of BRs exerted an opposite effect. The results indicated that these three hormones might also control ZePrx participation in xylem lignification (Gutiérres et al 2009). …”

Purification and characterization of a peroxidase present in xilopodium exsudates of umbu plants (Spondias tuberosa A.)

“…Several class III peroxidases are glycosylated in many residues and it confers stability to high temperature and pH variation (Mathé et al, 2010). Plants can express several peroxidases involved in different physiological process such as defense mechanisms acting against pathogens (Kuzaniak and Sklodowska, 2005;Almagro et al, 2009), hormone regulation (Gutiérrez et al, 2009), lignin biosynthesis, oxidation of lignin precursor phenols (Fagerstedt et al, 2010), and responses to abiotic stresses including UV radiation and drought (Kim et al, 2007;Krishnamurthy et al, 2009). The relationship between peroxidase and water stress is related to protection of plant tissues against the oxidative stress built up under this condition (Reddy et al, 2004).…”

Purification and enzymatic properties of a peroxidase from leaves of Phytolacca dioica L. (Ombú tree)

“…Moreover, PODs can be found in vacuoles, tonoplast, plasmalemma and inside and outside the cell wall. These enzymes are reported to be involved in plant hormone regulation (8), defence mechanisms (9), control of cell elongation, polymerization of extensin (10), cross-linkage of cell wall polysaccharides (11), lignin biosynthesis (12) and suberization processes (13). In addition, it is generally accepted that the pattern of peroxidase isoenzymes changes during plant development.…”