Differential induction of apoplastic peroxidase and chitinase activities in susceptible and resistant wheat cultivars by Russian wheat aphid infestation

Antagonistic yeasts competes for iron with winter wheat stem base pathogens

“…The defense responses of different plant varieties have been widely discussed in literature. Westhuizen et al (1998), who studied the defense responses of several wheat cultivars to aphid infestation, found that peroxidase activity increased in resistant varieties after 2 days. A rapid increase in chitinase activity levels was also observed in some resistant wheat varieties as soon as after 1 day.…”

Phloem Feeding Insect Stress and Photosynthetic Gene Expression

“…Although, such a phytotoxin has never been described or isolated, ultrastructural studies revealed limited chloroplast breakdown in the leaves of resistant cultivars after aphid feeding (Van der Westhuizen et al, 1998). Since cell fluorescence data has shown that D. noxia feeding causes reduced photosynthetic capacity even in intact chloroplasts (Haile et al, 1999), this chloroplast rupture mechanism seems unlikely.…”

“…However, for an effective hypersensitive response-based programmed cell death to occur, a cascade of events have to occur, including production of ROIs and associated downstream defensive responses. Indeed, increases in the activity of oxidative enzymes such as peroxidases, polyphenol oxidases and lipoxygenases were observed after Diuraphis noxia feeding ( Van der Westhuizen et al, 1998;Ni et al, 2000Ni et al, , 2001. This increase occurs not only at the site of feeding, but it also spreads systemically ( Van der Westhuizen et al 1998 (Asada, 1999).…”

“…Indeed, increases in the activity of oxidative enzymes such as peroxidases, polyphenol oxidases and lipoxygenases were observed after Diuraphis noxia feeding ( Van der Westhuizen et al, 1998;Ni et al, 2000Ni et al, , 2001. This increase occurs not only at the site of feeding, but it also spreads systemically ( Van der Westhuizen et al 1998 (Asada, 1999). A variety of mechanisms exist for the dissipation of excess excitation that may give rise to the generation of reductants and the production of ROIs, act as signalling agents, or to serve as alternative Time (hours post-infestat ion) Fig.…”

Identification of candidate genes at the Dp-fl locus conferring resistance against the rosy apple aphid Dysaphis plantaginea

“…The saliva containing these signals is transported in the phloem flow, but the mechanism of action is still unclear (Miles 1999). Moreover, these signals alter the expression of inducible plant physiological factors involved in defense against pathogens (Van Der Westhuizen et al 1998;Fidantsef et al 1999). Aphids may also transmit various plant viruses through the saliva causing irrevocable damage to the plant (Martín et al 1997;Ng and Perry 2004).…”