engleski

Stress-induced somatic embryogenesis in pumpkin (C. pepo L.)

Proembryo production in pumpkin can be induced by low concentrations of NH4Cl as a sole source of nitrogen, or by 2, 4-D. Subsequent addition of nitrogen in the first case, and removal of auxin in the second, stimulate more advanced stages of embryo development. Proembryogenic cells from the two systems showed differences in growth parameters and patterns of callose deposition. The latter disappeared when the tissue was transferred onto a medium that enables late embryo development. The activities of soluble peroxidase (EC 1.11.1.7), esterase and phenylalanine ammonia-lyase, enzymes shown to be markers of stress response and embryo development, were the highest in tissue grown in NH4+-only medium which reflects highly proembryogenic state of the culture. Enzymatic activities decreased after buffering of the medium with MES, and additionally decreased after re-supply of different forms of nitrogen or in medium with 2, 4-D. The effect of L-glutamine on somatic embryogenesis was stronger than that of nitrate. The role of stress during early somatic embryogenesis in pumpkin will be discussed.

Cucurbita pepo L.; esterases; nitrogen deficiency; phenylalanine ammonia-lyase; peroxidases; somatic embryogenesis

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