Copper Amine Oxidase Expression in Defense Responses to Wounding and Ascochyta rabiei Invasion

Abstract

Wounding chickpea (Cicer arietinum) internodes or cotyledons resulted in an increase in the steady-state level of copper amine oxidase (CuAO) expression both locally and systemically. Dissection of the molecular mechanisms controlling CuAO expression indicated that jasmonic acid worked as a potent inducer of the basal and wound-inducible CuAO expression, whereas salicylic acid and abscisic acid caused a strong reduction of the wound-induced CuAO expression, without having any effect on the basal levels. Epicotyl treatment with the CuAO mechanism-based inhibitor 2-bromoethylamine decreased hydrogen peroxide (H 2 O 2 ) levels in all the internodes, as evidenced in vivo by 3,3Ј-diaminobenzidine oxidation. Moreover, inhibitor pretreatment of wounded epicotyls resulted in a lower accumulation of H 2 O 2 both at the wound site and in distal organs. In vivo CuAO inhibition by 2-bromoethylamine after inoculation of resistant chickpea cv Sultano with Ascochyta rabiei resulted in the development of extended necrotic lesions, with extensive cell damage occurring in sclerenchyma and cortical parenchyma tissues. These results, besides stressing the fine-tuning by key signaling molecules in wound-induced CuAO regulation, demonstrate that local and systemic CuAO induction is essential for H 2 O 2 production in response to wounding and indicate the relevance of these enzymes in protection against pathogens.Plant defense responses are accomplished by the deployment of a complex array of events that are differentially modulated depending on the incoming stress (Maleck and Dietrich, 1999). Wounding different plant organs or interaction with pathogens induce local and systemic accumulation of defenserelated proteins (Hammond-Kosack and Jones, 1996;Ryals et al., 1996;Ryan, 2000). The study of signaling events inducing local and systemic responses led to the discovery of systemin, jasmonates, ethylene, salicylic acid (SA), and abscisic acid (ABA) as signal molecules (Peñ a-Cortés et al., 1989; Farmer and Ryan, 1990; Pearce et al., 1991;Xu et al., 1994; O'Donnell et al., 1996;Schweizer et al., 1998;van Loon et al., 1998; Knoester et al., 1999).The existence of multiple defense strategies and complex signaling networks leads to an enhanced defense capacity of the plants. The signal transduction pathways of wounding and pathogen attack may be common, different, or exclusive, depending on the biological system, but likewise the establishment of defense mechanisms requires the presence or accumulation of hydrogen peroxide (H 2 O 2 ; Sutherland, 1991; Mehdy, 1994; Hammond-Kosack et al., 1996). In particular, H 2 O 2 behaves as a direct cytotoxic compound against pathogens and as a second messenger in the activation of defense genes (Lamb and Dixon, 1997). Moreover, this compound is involved in systemic acquired resistance and acts synergistically with NO in the induction of hypersensitive cell death (Delledonne et al., 1998). As a cosubstrate of the peroxidases, H 2 O 2 has been implicated in the oxidative cross-linking of apoplastic st...

Apoplastic Polyamine Oxidation Plays Different Roles in Local Responses of Tobacco to Infection by the Necrotrophic FungusSclerotinia sclerotiorumand the Biotrophic BacteriumPseudomonas viridiflava

“…This observation is in good agreement with previous works that found oxidative responses to increase the severity of infections caused by necrotrophic pathogens in plant hosts (Govrin and Levine, 2000;Mayer et al, 2001). On the other hand, results of this work are in apparent contradiction with those of Rea et al (2002), who found DAO to participate in cell wall strengthening as part of chickpea (Cicer arietrinum) local responses to Ascochyta rabiei, and proposed that this enzyme contributes to plant tolerance to infection by this necrotrophic fungus. However, these authors based their conclusions on experiments performed by infiltrating a DAO inhibitor into chickpea tissues once infection was already established, as opposed to this work, in which infiltrations with the inhibitors were done prior to infection.…”

“…However, the attention previously devoted to the effects of necrotrophic plant pathogens on host PA metabolism has been very scant (Angelini et al, 1993;Rea et al, 2002). In this work, tobacco plants infected by the ascomycete S. sclerotiorum were used as a model for the study of perturbations induced by necrotrophic pathogens on host PA metabolism.…”

“…Thus, the abovementioned works indicate that PA oxidation plays a role in cell death programs associated to the HR. Moreover, hydrogen peroxide derived from PA oxidation has been shown to contribute to wound healing (Angelini et al, 2008) and cell wall reinforcement in response to invasion of chickpea (Cicer arietinum) tissues by the fungal pathogen Ascochyta rabiei (Rea et al, 2002).…”

Expression of a GDP-L-galactose phosphorylase-like gene in a Chinese wild Vitis species induces responses to Erysiphe necator and defense signaling molecules

“…Moreover, the existence of multiple defense strategies and complex signaling networks in plants leads to enhanced defense capacity (Rea et al, 2002). Induced defense responses are regulated by a network of inter-connecting signal transduction pathways, in which the hormonal signals SA, MeJA, and Eth play a major role.…”

Cell Death Processes during Expression of Hybrid Lethality in Interspecific F1 Hybrid between Nicotiana gossei Domin and Nicotiana tabacum

“…To further dissect the role of ROI in the process of cell death, we detected endogenous hydrogen peroxide (H 2 O 2 ) in the plants by 3,3Ј-diaminobenzidine oxidation (Thordal-Christensen et al, 1997;Rea et al, 2002). The accumulation of 3,3Ј-diaminobenzidine oxidation product in the seedlings grown at 26°C and 37°C is shown in Figure 9A.…”