ENDOGENOUS HORMONE LEVELS DURING DIRECT SOMATIC EMBRYOGENESIS IN MEDICAGO-FALCATA

Endogenous indole-3-acetic acid, abscisic acid and cytokinins (zeatin, zeatin riboside, N-isopentenyladenine and N-isopentenyladenosine) wer e evaluated in initial explants (leaves) of in vitro propagated plants of alfalfa (Medicago falcata L.) lines varying in embryogenic capacit y and during the somatic embryogenesis process. Fast embryogenic induc tion was correlated with high IAA and low ABA levels in the initial ex plants. No significant differences were observed in the cytokinin cont ents. Our results suo est that a certain hormone balance is necessary to allow the expression of oa the embryogenic potential. The consisten t stages of the direct somatic embryogenesis are also characterized by changes in hormonal levels.