Competitive antagonism between IAA and indole alkaloid hypaphorine must contribute to regulate ontogenesis

Since 1995 the role of fungal hypaphorine in plants has been widely investigated and its IAA-antagonist activity recognized. Evidence of competitive antagonism includes organ development, gene expression or molecule-molecule interaction levels. Based on present knowledge, three sites of hypaphorine/IAA competition and subsequent signalling pathways have been hypothesized: the extracellular signalling pathway, the intracellular signalling pathway, and the transmembrane signalling pathway. Hypaphorine with other active indole alkaloids should be regarded as a new class of IAA antagonist finely regulating specific steps of plant growth or development.