A Gene-controlled Flowering Inhibitor in Pisum

Abstract

VON DENFFER¹ has recently suggested that the stimulus to flowering is not brought about by the production of a new flowering hormone (‘florigen’) but results from the sudden drop in production of a flower inhibitor substance (‘Blühhemmstoff’). We have been investigating the mode of action of the genes controlling the earliness or lateness of flowering in the garden pea, and have evidence that the late varieties are late because they produce an inhibitor which is absent from the earlies. We have used three varieties: Massey, which normally flowers about the ninth node; Richard Seddon, which flowers at about the fourteenth node; and Telephone, flowering at the seventeenth node. Pellew² has suggested that a series of three multiple alleles, L, l₁ and l₂, determine these differences in flowering behaviour, the dominant L gene determining late flowering (eighteenth node). It is probable that our three varieties are respectively l₂l₂, l₁l₁ and LL. However, the genetical tests are not yet complete.