Quantitation of gibberellins and indoleacetic acid in Begonia leaves: Relationship with environment, regeneration and flowering |
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Authors: | Per Christer Odén Ola M Heide |
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Institution: | Dept of Forest Genetics and Plant Physiology, Swedish Univ. of Agricultural Sciences, S-901 83, Umeå, Sweden.;Dept of Botany, Agricultural Univ. of Norway, P. O. Box 14, N-1432 Ås-NLH, Norway. |
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Abstract: | Indole-3-acetic acid (IAA) was purified by high performance liquid chromatography (HPLC) and identified by gas chromatography - mass spectrometry (GC-MS) in leaf extracts of Begonia × cheimantha Everett cv. Nova. The content of IAA and of gibberellins A4, A9, A19 and A20 (GAs) previously identified in this material, were quantified by GC-MS in leaves of Begonia plants grown under different temperature and daylength conditions, using deuterated compounds as internal standards. GA1, which was also identified, was present in too low quantities for reliable quantitation. Rapid and significant decreases (within 2–4 days) occurred in the content of both IAA and GAs when the plants were transferred from conditions which are non-inductive for adventitious bud formation and flowering (24°C/long day) to inductive conditions (24°C/short day, 15°C/long day or 15°C/short day). GA4 and GA9 were affected by photoperiod only, whereas IAA, GA19 and GA20 were affected by both photoperiod and temperature. The data suggest that biosynthesis of GA9 and GA4 are blocked in short days at a step located before GA9. Conversion of GA19 to GA20 seemed to be blocked by both short days and low temperature, while an additional block located before GA19 seemed to be imposed in 15°C/short day. The results confirm earlier results and support the hypothesis that photoperiod and temperature effects in Begonia are mediated by endogenous hormones. |
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Keywords: | Auxin Begonia bioassay gas chromatography-mass spectrometry flowering gibberellins hormones indoleacetic acid photoperiod radioimmuno-assay regeneration temperature |
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