Suppression of the Defence‐Related Oxidative Burst in Bean Leaf Tissue and Bean Suspension Cells by the Necrotrophic Pathogen Botrytis cinerea

Abstract

The interaction of two selected isolates of Botrytis cinerea with bean suspension cells and bean leaf discs was compared in relation to levels of reactive oxygen intermediates (ROI). Isolate B 1.7 was arrested by a hypersensitive-like necrosis of bean leaf tissue. According to its inability to spread and produce conidia on the bean leaf tissue it was classified as non-aggressive. The second isolate induced a fast expanding light brownish necrosis of the leaf tissue. It was able to produce conidia on bean leaf discs and was classified as aggressive. The generation of superoxide was followed biochemically in inoculated bean cell suspensions. Both isolates induced a similar early superoxide peak approximately 18-h post inoculation (hpi). While the non-aggressive isolate induced a much stronger secondary superoxide burst at 33 hpi, the level of superoxide of suspension cells inoculated with the aggressive isolate was below the control level. This is the first report on the occurrence of a biphasic oxidative burst in plant cells induced by a fungal pathogen. Such a suppression of superoxide generation was also observed in bean leaf discs inoculated with the aggressive isolate. An oxidative burst-suppressing agent was extracted from inoculated cell culture medium and determined as 2-methyl-succinate (2-MS) by GC/MS analysis. The compound was detected approximately 20 hpi in the aggressive fungus-plant interaction. 2-MS was able to suppress the hypersensitive response-like necrosis on leaf discs as well as the second superoxide burst in suspension cells when inoculated with the nonaggressive isolate. The early superoxide burst at 18 hpi was not affected. The results confirm the important role of enhanced production of ROI in plant resistance reactions, also for a necrotrophlike B. cinerea.U. S.

Spatial and temporal variation in damage and dieback in a threatened subantarctic cushion species

“…A yellow discoloration of leaf tissue has been previously observed in pathogen-affected plants (Tamada and Baba 1973;TraperoCasas and Jiménez-Díaz 1985). Brown discolorations have been observed in other cases (Scortichini and Lazzari 1996;Unger et al 2005;Bobev et al 2009), and a variety of discolorations ranging from yellow to brown in still others (Johnson and Littrell 1969;Fradin and Thomma 2006).…”

Resistance to Botrytis cinerea in sitiens, an Abscisic Acid-Deficient Tomato Mutant, Involves Timely Production of Hydrogen Peroxide and Cell Wall Modifications in the Epidermis

“…Previously, resistance of tomato plants against B. cinerea infection has been demonstrated to result from early stimulation of H 2 O 2 and superoxide radical generation by NADH peroxidase and superoxide dismutase in the apoplastic space (Patykowski and Urbanek, 2003). Moreover, whereas an aggressive isolate of B. cinerea induces expanding palebrown necrosis, a nonaggressive isolate is arrested by biphasic oxidative burst and HR-like necrosis on bean leaf tissue (Unger et al, 2005).…”

“…Nevertheless, the role of ROS in defense against B. cinerea remains controversial. Some studies suggest a positive effect of ROS on plant resistance: Chemical induction of oxidative burst in tomato (Solanum lycopersicon) with O-hydroxyethylorutin resulted in resistance (Malolepsza and Urbanek, 2002) and a biphasic oxidative burst has been reported in bean cells attacked by B. cinerea (Unger et al, 2005). The secondary oxidative burst was much stronger in infections with a nonaggressive rather than with an aggressive strain, which led to the conclusion that ROS-mediated HR-like cell death was able to block B. cinerea.…”

The origin of reactive oxygen during interaction of Pinus sylvestris root and Heterobasidion annosum s.l. – the linkage with the iron

“…Thus, plants, which induce ROS bursts should limit the spread of biotrophic, but not necrotrophic fungi (Shetty et al 2008). However, this assumption is an over-generalization, because even genotypes of Botrytis cinerea Pers., known as a necotrophic pathogen, can generate reactive oxygen bursts (Govrin and Levine 2000) might also be restricted by ROS (Unger et al 2005).…”