Heterologous Expression of Septoria lycopersici Tomatinase in Cladosporium fulvum: Effects on Compatible and Incompatible Interactions with Tomato Seedlings

Abstract

The anti-fungal, steroidal, glycoalkaloid saponin, alpha-tomatine, is present in uninfected tomato plants in substantial concentrations, and may contribute to the protection of tomato plants against attack by phytopathogenic fungi. In general, successful fungal pathogens of tomato are more resistant to alpha-tomatine in vitro than fungi that do not infect this plant. For a number of tomato pathogens, this resistance has been associated with the ability to detoxify alpha-tomatine through the action of enzymes known as tomatinases. In contrast, the biotrophic tomato pathogen Cladosporium fulvum is sensitive to alpha-tomatine and is unable to detoxify this saponin. This paper describes the effects of heterologous expression of the cDNA encoding tomatinase from the necrotroph Septoria lycopersici in two different physiological races of C. fulvum. Tomatinase-producing C. fulvum transformants showed increased sporulation on cotyledons of susceptible tomato lines. They also caused more extensive infection of seedlings of resistant tomato lines. Thus, alpha-tomatine may contribute to the ability of tomato to restrict the growth of C. fulvum in both compatible and incompatible interactions.

Investigations of Globodera pallida invasion and syncytia formation within roots of the susceptible potato cultivar Désirée and resistant species Solanum canasense

“…Wild Solanum species may have several steroid glycoalkaloids, including α-solanine and α-chaconine, which have been previously related to resistance to a range of pests and pathogens (Zhuchenko et al, 1975;Flanders et al, 1992;Melton et al, 1998;Ronning et al, 2000). Steroid glycoalkaloids have been shown to be toxic to nematodes (Zhuchenko et al, 1975;Allen & Feldmesser, 1970) and, speculatively, the presence of such glycoalkaloids in higher concentrations may result in the roots being inherently unattractive.…”

Molecular Biology in Plant Pathogenesis and Disease Management

“…Further, Cladosporium fulvum sensitive to ␣-tomatine can successfully induce disease in tomato. However, the transformants of C. fulvum expressing a heterologous expression of cDNA encoding tomatinase from Septoria lycopersici showed increase in sporulation in susceptible tomato lines and the symptoms caused were more severe in resistant lines compared to wild-type (Melton et al 1998).…”

Evaluation of microbial elicitors to induce plant immunity for tomato wilt

“…The experiment was perperformed to detect α-tomatine in laboratory. The trial was conducted with a modified method of Melton et al (1998) and designed in Completely Randomized Design (CRD) with six treatments and three replications. Twenty-day-old seedlings var.…”

“…High quantity of -tomatine was detected from fresh green fruits as 0.9-55 mg/100 g plant fresh weight. Moreover, Melton et al (1998) reported that tomato seedlings var. Moneymaker Cf4 and Cf5at 11 day-old were inoculated with conidial suspension of Cladosporium fulvum at concentration as 5 × 10 5 conidia/ml.…”