Role of polyamines in the infection of sugarcane buds by Ustilago scitaminea spores

Experimental infection of sugarcane buds from sensitive (Barbados 42231) and resistant (Mayarي 5514) cultivars of sugarcane hybrids to smut with teliospores of Ustilago scitaminea leads to a remarkable increase of both free and conjugated polyamines. Whereas resistant buds mainly produce free putrescine, the sensitive cultivars produce acid soluble-conjugated as well as acid insoluble-conjugated spermidine and spermine after infection. A net maximum of both polyamines is reached 13 or 17 d after infection and levels decrease later. This maximum after infection is always higher than that found for non-infected buds. Variation of cadaverine, also produced by sugarcane buds, does not show any clear correlation with smut development.