Regenerative Capacity of Cacti Schlumbergera and Rhipsalidopsis in Relation to Endogenous Phytohormones, Cytokinin Oxidase/Dehydrogenase, and Peroxidase Activities |
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Authors: | Sridevy Sriskandarajah Els Prinsen Václav Motyka Petre Ivanov Dobrev Margrethe Serek |
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Institution: | (1) Department of Agricultural Sciences, Crop Science, Floriculture, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, 1871, Frederiksberg C, Denmark;(2) Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerpen, Belgium;(3) Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 135, CZ-16502 Prague 6, Czech Republic;(4) Ornamental and Woody Plant Science, Department of Natural Sciences, University of Hanover, Herrenhaeuser Str. 2, 30-419, Hanover, Germany |
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Abstract: | The recalcitrant nature and increased regenerative capacity in relation to in vitro subcultures in two cactus genera Rhipsalidopsis (Easter cactus) and Schlumbergera (Christmas cactus) were studied by examining the endogenous concentrations of several endogenous phytohormones and enzyme
activities. Leaf tissue from greenhouse-grown mother plants, in vitro subcultures 1 and 3, and callus tissues were analyzed and correlated with regenerative ability. The cytokinins present in
the two cacti genera were mainly isopentenyl-type derivatives. The total content of isopentenyl-type cytokinins in greenhouse-grown
leaves of Rhipsalidopsis was more than twice the amount found in greenhouse-grown leaves of Schlumbergera. The total cytokinin content decreased during subculturing. Cytokinin oxidase/dehydrogenase (CKX, EC 1.4.3.18/1.5.99.12)
activity increased during subculturing. In Schlumbergera there is no effect of subculturing on CKX and related cytokinin homeostasis. The total peroxidase (POX, EC 1.11.1.7) activity
in greenhouse-grown leaves of both genera was low, and the activity increased significantly during subculturing, more specifically
in the tissue of Rhipsalidopsis. The results clearly indicated that an enhanced auxin metabolism (biosynthesis, conjugation/deconjugation, and POX activity),
in combination with an enhanced CKX activity, shifts the auxin and cytokinin pool, favoring adventitious shoot formation in
Rhipsalidopsis, whereas the low level of POX activity, together with auxin autotrophy/conjugation, makes Schlumbergera more recalcitrant.
S. S. and E. P. contributed equally to this work |
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Keywords: | Cytokinin dehydrogenase Cytokinin oxidase Endogenous phytohormones In vitro regeneration Peroxidase Rhipsalidopsis Schlumbergera |
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