NATURALLY-OCCURRING PHYTOHORMONES IN WHEAT EXPLANTS AS RELATED TO WHEAT MORPHOGENESIS IN-VITRO

The levels of endogenous phytohormones in the explants (immature embry os) and derived morphogenic callus tissues of wheat (Triticum aestivum L.), cv. Taezhnaya and line Fotos, were assayed. The explants from li ne Fotos contained more cytokinins but less IAA and ABA, as compared w ith those from cv. Taezhnaya. When these explants were cultured on the same nutrient medium under similar growth conditions, they behaved di fferently: line Fotos produced callus tissues more rapidly than cv. Ta ezhnaya. The two genotypes also differed in the frequency of morphogen ic tissue formation and regeneration capacity. After two subcultures, initial differences in the phytohormone levels between the two genotyp es diminished, and the morphogenic callus of both genotypes was essent ially similar in the relative contents of different phytohormones. End ogenous phytohormone status is supposed to be one of the factors affec ting the induction of callus formation and morphogenesis. Exogenous 2, 4-D exerts noticeable effects on the endogenous phytohormone contents during long-term tissue culturing.