Increased Activity of a Cationic Peroxidase Associated with an Incompatible Interaction Between Xanthomonas oryzae pv oryzae and Rice (Oryza sativa)

Abstract

Rice (Oryza sativa L.) cultivar Cas 209 carries the gene Xa-10 for resistance to race 2 of Xanthomonas oryzae pv oryzae, the bacterial blight pathogen. When seedling leaves of Cas 209 plants were infiltrated with bacterial cell suspensions of strain PX086RIf (race 2, incompatible), total peroxidase activity in extracts from extracellular spaces increased almost threefold between 16 and 24 hours after inoculation. The increase in total peroxidase activity in extracellular extracts was correlated with the appearance of a 43-kilodalton peroxidase isoenzyme with an isoelectric point of 8.6. Increases in the activities of two anionic peroxidase isoenzymes also were associated with the incompatible interaction. Later during the interactions, total peroxidase activities increased in both compatible (cv Cas 209 infiltrated with race 1, PXO61sm) and control (Cas 209 infiltrated with water) treatments, but final activity levels were less than that observed in the incompatible combination. Similarly, the cationic peroxidase was detected in all three treatments by 48 hours after infiltration, but at reduced levels in compatible and water-infiltrated control treatments relative to the incompatible combination. Accumulation of this peroxidase in extracellular spaces thus may play a role in the defense response in cultivar Cas 209. Rice (Oryza sativa L.) is one of the most important cereal crops worldwide, sustaining more than one-half of the global population (20). Like many plant species, rice employs a diverse array of defenses that minimize losses during pathogen attack. For example, melanin deposition and coordinated increases in peroxidase activities and phenolic compounds are associated with the colonization of rice leaves by Magnaporthe grisea, the blast pathogen (26, 30). Phenolic compounds toxic to Xanthomonas oryzae pv oryzae, the causal agent of bacterial blight, also are found in greater amounts in healthy leaves of resistant cultivars compared to healthy leaves of susceptible cultivars (9). Phytoalexins are thought

Trichoderma oligosaccharides priming mediates resistance responses in pearl millet against downy mildew pathogen

“…Several reports on DM-PM interaction with significance to priming with elicitors have been done. Our present findings are also in concurrence with the findings enhanced levels of defenserelated enzymes observed in crude oligosaccharide treated PM seedlings and further increased after S. graminicola infection specifies that seed treatment of PM with oligosaccharides makes an incompatible atmosphere for infection, production and sporulation by S. graminicola which directs to the disease inhibition [39,40,41]. Oligosaccharides extracted from the cell wall of T. asperellum shows significantly (P ≤ 0.05) enhanced defense activity in PM plant and control the DM infection.…”

Elicitation of resistance in pearl millet by oligosaccharides ofTrichodermaspp. against downy mildew disease

“…The above findings suggest the role for these defense-related molecules in the expression of induced resistance by oligosaccharide elicitor against S. graminicola invasion in PM. Elevated levels of defense-related enzymes and signaling molecules recorded in oligosaccharide treated PM seedlings and their further increase after S. graminicola infection indicates that seed treatment of PM with oligosaccharides creates an incompatible environment for infection, proliferation, and sporulation by S. graminicola which leads to the disease suppression (Reimers et al 1992;Young et al 1995;Pushpalatha et al 2011). As in the case of PMÁDM interaction, it is critically important to characterize the structural elements required for the recognition and the receptor molecules to understand the molecular basis for the perception and transduction of elicitor signals.…”

Rice Cationic Peroxidase Accumulates in Xylem Vessels during Incompatible Interactions with Xanthomonas oryzae pv oryzae

“…In resistant or incompatible interactions between rice and the bacterial blight pathogen, Xanthomonas oyzae pv oryzae, increases in the activities of three extracellular peroxidases (two anionic [PO-A1 and PO-A2] and one cationic [PO-Cl]) have been correlated with the accumulation of lignin-like compounds, a reduction in bacterial multiplication in the leaves, and the onset of the HR (Reimers and Leach, 1991;Reimers et al, 1992;Guo et al, 1993). Activity of the cationic peroxidase PO-C1 increased more dramatically with the onset of resistance when compared with the two anionic peroxidases (Reimers et al, 1992).…”