Polyamine synthesis and accumulation in the hypersensitive response to TMV in Nicotiana tabacum

Abstract

SUMMARYThe possible involvement of polyamines in the tobacco mosaic virus (TMV)-induced hypersensitive reaction (HR) in Nicotiana tabacum (L.) cv. Samsun NN, which bears the N resistance gene, was investigated. Concentrations of free and conjugated polyamines, as well as the activities of their biosynthetic enzymes ornithine decarboxylase (ODC) and arginine decarboxylase (ADC), were analysed in the necrotic area (I, internal zone) and in the two concentric zones surrounding it (M, middle zone; E, external zone) during the progression of the HR (1, 3 and 5 d from TMV inoculation). Results were compared with those obtained in control plants (mockinoculated) and with the pattern in susceptible TMV-infected tobacco plants.In the HR, concentration increased towards zone I for free putrescine and spermidine. Highest concentrations in zones M and I occurred on day 3. Conjugated polyamines similarly showed an increasing concentration gradient towards zone I, with maximum accumulation on day 5. ODC and ADC activities also showed an increasing gradient towards zone I that could be related to the increase in free and conjugated polyamines. By contrast, in control plants concentrations of free and conjugated polyamines decreased from day 1 to day 5, ODC activity increased slightly, whereas ADC activity did not show significant changes. In the TMV-infected susceptible tobacco plants, polyamines tended to remain in the free state instead of being conjugated as infection progressed. These results suggest that polyamines could play a role in mechanisms of resistance to biotic stress.

Spermine Is a Salicylate-Independent Endogenous Inducer for Both Tobacco Acidic Pathogenesis-Related Proteins and Resistance against Tobacco Mosaic Virus Infection

“…First, synthesis of Spm is highly activated in necrotic tissue, yet the total amount of Spm decreases because consumption is enhanced. This possibility is supported by the finding that Put and Spd, precursors of Spm, are synthesized and highly accumulated around necrotic lesions on TMVinfected tobacco (Torrigiani et al, 1997). We in the present study and Scalet et al (1991) found that the amount of Put was significantly increased by mechanical wounding in both TMV-infected and mock-inoculated tobacco leaves and in wounded chickpea leaves, respectively.…”

Short‐term polyamine response in TMV‐inoculated hypersensitive and susceptible tobacco plants

“…In several higher plants, especially in the Solanaceae, polyamines have been shown to form mono-substituted and di-substituted basic amides with hydroxycinnamic acids (HCAs) ; these have been reported to be involved in the defence mechanism in several plant-pathogen interactions (Favali et al, 1997 ;Torrigiani et al, 1997 ;Walters & Mackintosh, 1997). The possibility now exists of manipulating polyamine metabolism in order to control plant diseases.…”

“…Less is known about susceptible (nn) tobacco plants in which TMV produces a systemic infection (Staskawicz et al, 1995). Torrigiani et al (1997) reported that in NN tobacco cv. Samsun, concentrations of free and conjugated polyamines increased towards the centre of the HR lesion ; maximum accumulation of free polyamines occurred 3 d after inoculation, whereas conjugates peaked 2 d later.…”

“…Samples (0n5-1n0 g) were homogenized in five volumes of 100 m Tris-HCl, pH 8n5, containing 50 µ pyridoxalphosphate. CO # released from labelled-ornithine and arginine was measured following the procedure previously optimized for tobacco (Altamura et al, 1993) and described by Torrigiani et al (1997). The concentration of 2 m unlabelled substrate was chosen in consideration of the K m values reported for other higher plants (Slocum, 1991).…”

Respostas de calos de cana-de-açúcar na interação com bactérias diazotróficas endofíticas.

“…NO também reage rapidamente com proteinas, especialmente amino ácidos reativos como cisteína e tirosina e com vários receptores e fatores de transcrição (STAMLER et al, 2001). NO pode induzir genes envolvidos na defesa e proteção da célula (FERRARINI et al, 2008 A planta, ao reconhecer um microrganismo invasor desencadeia uma resposta hipersensível, onde são liberadas EROs e NO, para delimitar a zona infectada e suprimir a multiplicação do patógeno (FLORES et al, 2008;HONG et al, 2008 A espermina é a poliamina biologicamente mais ativa que as demais, agindo na estabilização das membranas celulares, interagindo com proteínas nucleares, estimulando a síntese de pectina e de hemicelulose, além de exercer ação antioxidante (BOUCHEREAU et al, 1999) Alguns trabalhos mostram uma relação entre poliaminas e infecção da planta por patógenos, pois, nestas circunstâncias foi observado um aumento no nível de poliaminas, particularmente de espermina e espermidina (YAMAKAWA et al, 1998;TORRIGIANI et al, 1997). Não foi encontrado nenhum artigo que relacionasse a concentração de poliaminas em associações benéficas planta/bactéria.…”