Auxin and phyllotaxis

Our understanding of phyllotaxis is still largely based on surgical and pharmacological experiments carried out before 1970. Recent experiments implicate the plant hormone auxin in the regulation of phyllotaxis. A recent paper shows how the polar auxin transport mutant, pin1-1, which fails to make flowers, affects the expression of well known meristem genes. This work opens the door for the genetic analysis of phyllotaxis.