Abstract
This symposium was organized to commemorate 70 years of the Chailakhyan's florigen concept and to discuss the strategies to resolve this classical but still-unsolved subject. Today, the definition of florigen is confusing and the concept is understood in several different ways. However, everyone may agree with an idea that some signal is transmitted from photoinduced leaves to shoot apex. What we want to know is what this signal is. I should call this signal florigen. Despite of many physiological studies during the past 70 years, its chemical nature is still obscure. The molecular studies have been progressing without considering the florigen concept. Thus, it seems that the florigen concept is being ignored. However, very recently, it was suggested that products of the genes expressed in the photoinduced leaves are transmitted to shoot apex. Such transmissible products can be considered florigen. The florigen study seems to enter the new era.
