Suppression of botrytis blight in rose flowers with gibberellic acid. Possible formation of endogenous inhibitory compounds

• Published in: Journal of plant physiology 1996, Vol.149 (5), p.580-584
• Main Authors: Zieslin, N., Shaul, O., Elad, Y.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Botrytis blight; Botrytis cinerea; Chemical control; Control; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; gibberellin; gray mold; induced resistance; phenols; Phytopathology. Animal pests. Plant and forest protection; Rosa × hybrida
• ISSN: 0176-1617; 1618-1328
• DOI: 10.1016/S0176-1617(96)80337-3

Elongation of conidial germ tubes as well as linear growth of colonies of the fungal pathogen Botrytis cinerea were inhibited when growth media in vitro were supplemented with leachates from GA 3-treated petals of rose ( Rosa × hybrida cv. Mercedes) flowers. Content of phenolic substances extracted from petals 6 days after the GA 3 treatment was higher than that in the control petals whereas no differences in content of phenols were found between the GA 3-treated and the control petals examined 8 days after the GA 3 treatment (9 days after harvest). Spore germination, germ tube elongation and mycelium growth were also inhibited when growth media in vitro were supplemented with phenolic extracts from petals treated with GA 3 6 days prior to extraction but not when they were extracted 8 days after the GA 3 treatment. Botrytis blight development in vivo was almost completely inhibited by phenolics extracted 6 days after GA 3 treatment and was also practically inhibited by extracts from older petals. The content of sugars and amino acids in leachates from GA 3-treated petals was lower than that in leachates from control petals. The inhibition of germ tube elongation in leachates from GA 3-treated petals was eliminated when the growth media were supplemented with excessive amounts of glucose. The inhibition of Botrytis blight development in GA 3-treated flowers in vivo was also eliminated when conidial suspensions were supplemented with glucose. The possible GA 3-imposed formation of inhibitory compounds with a phenolic moiety is discussed.