Localized stimulation of anthocyanin accumulation and delineation of pathogen ingress in maize genetically resistant to Bipolaris maydis race O
1996
Hipskind, J. | Wood, K. | Nicholson, R.L.
The present investigation is a continuation of our characterization of phenolic compound metabolism that occurs in the expression of resistance by maize with the recessive rhm gene for resistance to Bipolaris maydis. We show that a final stage of resistance expression involves the accumulation of a pigment in uninfected, healthy epidermal cells that surround restricted lesions on leaves of the resistant cultivar. The pigment was characterized by plasma desorption mass spectrometry and found to have a structure consistent with that of cyanidin 3-dimalonyl glucoside. The function of this zwitterionic anthocyanin is proposed to involve the protection of uninfected, healthy plant tissue from the toxic, oxidative metabolites that accumulate during the expression of resistance. Microscopic examination of leaf tissue showed that the pathogen ceased to grow in the resistant cultivar at 18 h post-inoculation, a time considerably prior to pigment accumulation. Thus, the pigment accumulates in cell that are affected but not infected by the pathogen.
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