Hormone physiology of pea mutants prevented from flowering by mutations gi or veg1

Abstract

The eg1 (egetatie) mutant in pea (Pisum satium L.) does growth. Endogenous hormone measurements and gibberellin not flower under any circumstances and gi (gigas) mutants application studies with gi-1, gi-2 and eg1 plants indicate remain vegetative under certain conditions. gi plants are defi- that a reduction in gibberellin and perhaps indole-3-acetic acid cient in production of floral stimulus, whereas eg1 plants lack level may account, at least partially, for the compact aerial a response to floral stimulus. During long days in particular, shoot phenotype. In the gi-1 mutant, the compact phenotype is these non-flowering mutant plants eventually enter a stable rescued by transfer from a 24- to an 8-h photoperiod. We compact phase characterised by a large reduction in internode propose that in plants where flowering is prevented by a lack length, small leaves and growth of lateral shoots from the of floral stimulus or an inability to respond, the large reducupper- stem (aerial) nodes. The first-order laterals in turn tion in photoperiod gene activity during long days may lead to produce second-order laterals and so on in a reiterative pat- a reduction in apical sink strength that is manifest in an tern. The apical bud is reduced in size but continues active altered hormone profile and weak apical dominance.