Journal Article

Cytokinins in the perianth, carpels, and developing fruit of Helleborus niger L.

Petr Tarkowski, Danuše Tarkowská, Ondřej Novák, Snježana Mihaljević, Volker Magnus, Miroslav Strnad and Branka Salopek-Sondi

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 57, issue 10, pages 2237-2247
Published in print July 2006 | ISSN: 0022-0957
Published online June 2006 | e-ISSN: 1460-2431 | DOI: https://dx.doi.org/10.1093/jxb/erj190
Cytokinins in the perianth, carpels, and developing fruit of Helleborus niger L.

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Reproductive development in the Christmas rose (Helleborus niger L.) differs from that in commonly investigated model plants in two important aspects: (i) the perianth develops a photosynthetic system, after fertilization, and persists until seed ripening; and (ii) the ripe seed contains an immature embryo which continues to mature off the mother plant. The possible roles of cytokinins in these processes are investigated here by analysing extracts of the perianth and the carpels/maturing fruit prepared during anthesis and four stages of post-floral development. trans-Zeatin, dihydrozeatin, N6-(Δ2-isopentenyl)adenine, and their ribosides were identified by tandem mass spectrometry. Single ion monitoring in the presence of deuterated internal standards demonstrated the additional presence of the corresponding riboside-5′-monophosphates, O-glucosides, and 9-glucosides, and afforded quantitative data on the whole set of endogenous cytokinins. Fruit cytokinins were mostly localized in the seeds. Their overall concentrations increased dramatically during early seed development and remained high for 6–8 weeks, until shortly before seed ripening (the last time point covered in this work). Overall cytokinin levels in the perianth did not change markedly in the period covered, but the level of N6-(Δ2-isopentenyl)adenine-type cytokinins appeared to increase slightly and transiently during the greening phase. The perianths of unpollinated or depistillated flowers, which survived, but did not pass through the complete greening process, contained significantly less cytokinins than observed in fruit-bearing flowers. This suggests that perianth greening requires defined cytokinin levels and supports the role of the developing fruit in their maintenance.

Keywords: Christmas rose; cytokinin identification and quantification; fruit and seed development; Helleborus niger L.; perianth greening

Journal Article.  5532 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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