A. Borner et al., GIBBERELLIN STATUS AND RESPONSIVENESS IN SHOOTS OF TALL AND DWARF GENOTYPES OF DIPLOID RYE (SECALE-CEREALE), Physiologia Plantarum, 89(2), 1993, pp. 309-314
The recessive dwarfing alleles of rye (Secale cereale L.), ct1 and ct2
, caused a 35-55% reduction in the length of leaf 2 compared with corr
esponding tall lines grown at both 10-degrees-C and 20-degrees-C. The
dwarf lines were 45-50% as responsive to applied GA3 as the tall lines
at 20-degrees-C but the absolute GA-responsiveness of the dwarfs, was
greater at 10-degrees-C than at 20-degrees-C. There was no significan
t difference in the contents of GA19, GA20, GA29, GA1, GA3, and GA8 in
the leaf extension zone of tall and dwarf seedlings grown at 20-degre
es-C. It was concluded that the mechanism whereby GA homeostasis is ma
intained is functional in both tall and dwarf lines despite marked dif
ferences in leaf extension rate. The recessive rye mutations may cause
loss of function late in the GA-cell elongation pathway or, alternati
vely. indirectly affect GA-responsiveness in vegetative tissues. The g
enetic and physiological evidence indicates that ct1 and ct2 are unrel
ated to the GA-insensitive Rht genes in hexaploid bread wheat.