Role of gibberellins in the thermoperiodic regulation of stem elongation in Dendranthema grandiflorum Tzvelev
1997
Nishijima, T. (National Research Inst. of Vegetables, Ornamental Plants and Tea, Ano, Mie (Japan)) | Nonaka, M. | Koshioka, M. | Ikeda, H. | Douzono, M. | Yamazaki,H. | Mander.L.N.
Role of endogenous gibberellins (GAs) in the thermoperiodic regulation of stem elongation in Dendranthema grandiflorum was investigated by gas chromatography-mass spectrometry with deuterated GAs as internal standards. GA1, GA20, GA19, GA44, and GA53, which all belong to the early 13-hydroxylation pathway of GA-biosynthesis, and GA9, which belongs to the early nonhydroxylation pathway, were identified from the stem. The thermoperiodic treatments employed were a higher day temperature than night temperature (DTNT) and several hours of temperature drop from beginning of the day (TD), TD markedly decreased the stem elongation rate when compared to the effect of DTNT. Further, TD decreased the concentrations of stem GA1, GA20, and GA19 more than DTNT, while TD increased the concentration of stem GA44 more than DTNT. Thus, TD probably retarded the conversion of GA44 to GA19, resulting in a low concentration of GA1, the probable biologically-active GA. These changes in endogenous GA concentration are probably an important physiological factor for the thermoperiodic regulation of stem elongation in D. grandiflorum
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