Induction of defence gene expression by oligogalacturonic acid requires increases in both cytosolic calcium and hydrogen peroxide in Arabidopsis thaliana

Abstract

Responses to oligogalacturonic acid (OGA) were determined in transgenic Arabidopsis thaliana seedlings expressing the calcium reporter protein aequorin. OGA stimulated a rapid, substantial and transient increase in the concentration of cytosolic calcium ([Ca 2+ ] cyt ) that peaked after ca. 15 s. This increase was dose-dependent, saturating at ca. 50 µg Gal equiv/ml of OGA. OGA also stimulated a rapid generation of H 2 O 2 . A small, rapid increase in H 2 O 2 content was followed by a much larger oxidative burst, with H 2 O 2 content peaking after ca. 60 min and declining thereafter. Induction of the oxidative burst by OGA was also dose-dependent, with a maximum response again being achieved at ca. 50 µg Gal equiv/mL. Inhibitors of calcium fluxes inhibited both increases in [Ca 2+ ] cyt and [H 2 O 2 ], whereas inhibitors of NADPH oxidase blocked only the oxidative burst. OGA increased strongly the expression of the defence-related genes CHS, GST, PAL and PR-1. This induction was suppressed by inhibitors of calcium flux or NADPH oxidase, indicating that increases in both cytosolic calcium and H 2 O 2 are required for OGA-induced gene expression.

The AtrbohD-Mediated Oxidative Burst Elicited by Oligogalacturonides in Arabidopsis Is Dispensable for the Activation of Defense Responses Effective against Botrytis cinerea

“…In contrast, DPI had no effect on Pep-13-induced PR gene expression (Kroj et al, 2003). In grapevine, the expression of six out of nine defenserelated genes responsive to OGs is blocked by DPI (Aziz et al, 2004), and in Arabidopsis Landsberg erecta seedlings treated with OGs, DPI blocks the expression of several defense genes (Hu et al, 2004). It is possible that the activation of a subset of late, secondary responses to elicitors is dependent, or at least is amplified by the earlier production of ROS.…”

N-3-Oxo-Decanoyl-l-Homoserine-Lactone Activates Auxin-Induced Adventitious Root Formation via Hydrogen Peroxide- and Nitric Oxide-Dependent Cyclic GMP Signaling in Mung Bean

“…The supernatant was collected and either processed immediately or quick frozen at 270°C until further analysis. The concentration of H 2 O 2 was measured as described previously (Hu et al, 2004). NO content was determined by hemoglobin assay following a reported method (Hu et al, 2005;Pasqualini et al, 2009).…”

“…Accumulated evidence demonstrates that both nitric oxide (NO) and hydrogen peroxide (H 2 O 2 ) are signals to participate in multiple physiological processes, including systemic acquired resistance, the hypersensitive response, leaf senescence, programmed cell death, stomatal closure, root gravitropism, cell wall development, pollen-stigma interaction, and development (Grant and Loake, 2000;Neill et al, 2002;Pagnussat et al, 2003;Hu et al, 2004;Mittler et al, 2004;Schuhegger et al, 2006;Xuan et al, 2008). Adventitious roots are derived primarily from plant stems and are essential for plant adaptation to environmental stress; studying the adventitious root formation is also significant for both fundamental and applied plant biology.…”

An Inositol Polyphosphate 5-Phosphatase Functions in PHOTOTROPIN1 Signaling in Arabidopis by Altering Cytosolic Ca2+

“…The measurements were performed in the luminometer cuvette (2 mL) containing coelenterazine (1 mM)-free base. The reading began after giving a 20-s blue light (20 mmol/ m 2 /s) pulse in the luminometer (FG-200) (Wang and Gu, 1986;Demidchik et al, 2004;Hu et al, 2004;Love et al, 2004). Fluorescence was generated by the sum of autofluorescence of chlorophyll and aequorin luminescence.…”