GIBBERELLIN-RESPONDING AND NON-RESPONDING DWARF MUTANTS IN FOXTAIL MILLET

The sensitivity of foxtail millet (Setaria italica Beauv.) dwarf mutan ts to GA was studied. Seedlings of dwarf mutants, Aininghuang (ANH) an d CH84113 were treated with GAs (GA(1), GA(4), GA(9), GA(19) and GA(20 )) using the micro-drop method, or by soaking in GA(3) solution. Plant s were also sprayed with GA(3) solution at the jointing stage. It was found that ANH was a GA-responding dwarf mutant, whose leaf blade, lea f sheath and internode length increased significantly after GA applica tion, whereas CH84113 was a non-GA-responding dwarf mutant. However, t he mesocotyl in etiolated seedlings of both ANH and CH84113 responded to exogenous GA(3) in a similar way. With the help of an enzyme-linked immunosorbent assay, it was found that the endogenous GA(1+3) level i n leaves was lower in the GA-responding dwarf mutant ANH, but higher i n the non-GA-responding dwarf mutant CH84113, compared with levels in normal cultivars.