Flavonoid-Induced Expression of a Symbiosis-Related Gene in the Cyanobacterium Nostoc punctiforme

The flavonoid naringin was found to induce the expression of hrmA, a gene with a symbiotic phenotype in the cyanobacterium Nostoc punctiforme. A comparative analysis of several flavonoids revealed the 7-O-neohesperidoside, 4′-OH, and C-2[bond ]C-3 double bond in naringin as structural determinants of its hrmA-inducing activity.