Effect of Yeast CTA1 Gene Expression on Response of Tobacco Plants to Tobacco Mosaic Virus Infection

Abstract

The response of tobacco (Nicotiana tabacum L. cv Xanthi-nc) plants with elevated catalase activity was studied after infection by tobacco mosaic virus (TMV). These plants contain the yeast (Saccharomyces cerevisiae) peroxisomal catalase gene CTA1 under the control of the cauliflower mosaic virus 35S promoter. The transgenic lines exhibited 2-to 4-fold higher total in vitro catalase activity than untransformed control plants under normal growth conditions. Cellular localization of the CTA1 protein was established using immunocytochemical analysis. Gold particles were detected mainly inside peroxisomes, whereas no significant labeling was detected in other cellular compartments or in the intercellular space. The physiological state of the transgenic plants was evaluated in respect to growth rate, general appearance, carbohydrate content, and dry weight. No significant differences were recorded in comparison with non-transgenic tobacco plants. The 3,3Ј-diaminobenzidine-stain method was applied to visualize hydrogen peroxide (H 2 O 2 ) in the TMV infected tissue. Presence of H 2 O 2 could be detected around necrotic lesions caused by TMV infection in non-transgenic plants but to a much lesser extent in the CTA1 transgenic plants. In addition, the size of necrotic lesions was significantly bigger in the infected leaves of the transgenic plants. Changes in the distribution of H 2 O 2 and in lesion formation were not reflected by changes in salicylic acid production. In contrast to the local response, the systemic response in upper noninoculated leaves of both CTA1 transgenic and control plants was similar. This suggests that increased cellular catalase activity influences local but not systemic response to TMV infection.Reactive oxygen species (ROS), such as ⅐ O 2 , hydrogen peroxide (H 2 O 2 ), and ⅐ OH, are associated with a number of physiological disorders in plants (Inzé and Van Montagu, 1995). Although ROS are produced as a product of normal cell metabolism, their levels are enhanced by exposure to biotic and abiotic stresses. It has been demonstrated that ROS, including H 2 O 2 , are a critical factor in the sequence of events taking place on the onset of infection, leading in many cases to hypersensitive response (HR) and the activation of the pathogenesis-related genes (PR), as well as in other processes associated with response to infection (for reviews, see Bolwell et al., 1995). The rapid generation of ROS as a result of pathogen attack is referred to as oxidative burst. A growing body of evidence suggests that this process is mediated by a membrane-bound NAD(P)H oxidase that resembles the phagocyte enzyme (Scheel, 2001). As the first step, the enzyme forms superoxide radicals, which are then converted to oxygen and hydrogen peroxide either spontaneously or by an extracellular superoxide dismutase. As an alternative, the contribution of other enzymes to the oxidative burst, like peroxidase, amine oxidase, or oxalate oxidase, is postulated (Bolwell et al., 1995; Allan and Fluhr, 1997; Zhou et al., 1998). ...

Reactive Oxygen Species and Plant Disease Resistance

“…Both PepMV infection and in planta overexpression of TGBp1 increased CAT activity and lowered H 2 O 2 levels, while silencing of CAT1 conferred a reduced accumulation of PepMV. The role of peroxisome-generated H 2 O 2 in resistance to plant viruses is also supported by an earlier study (Talarczyk et al 2002). Overexpression of a yeast peroxisomal catalase A1 gene (CTA1) in tobacco revealed that the CTA1 protein is indeed localized in peroxisomes of tobacco cells and likely confers a reduction in resistance to TMV.…”

Fatty Acid Hydroperoxides and H2O2 in the Execution of Hypersensitive Cell Death in Tobacco Leaves

“…It contributes to cell wall reinforcement, limiting pathogen spread, and it can also directly participate in pathogen killing. For example, in tobacco, the modulation of catalase activity by antisense technology leads to more resistant plants against pathogen attack (Mittler et al, 1999), whereas overproduction leads to more sensitive plants (Polidoros et al, 2001;Talarczyk et al, 2002). H 2 O 2 was shown to initiate a cell death program in Arabidopsis plants and suspension cultures (Desikan et al, 1998;Vandenabeele et al, 2004), in tobacco BY-2 cells (Houot et al, 2001), and in Cat1AS tobacco plants exposed to HL to activate a cell death process that involves the activation of an oxidative burst .…”

A Secreted Effector Protein ofUstilago maydisGuides Maize Leaf Cells to Form Tumors

“…Disease symptoms in the tassels were scored 14 DPI following the criteria described in a previous study (Schilling et al, 2014). Nicotiana benthamiana plants (BN3) were grown in a phytochamber (Vötsch) under controlled environmental conditions (21°C, 16 h of light, 8 h of dark) as described previously (Talarczyk et al, 2002).…”