The differential effects of C-16,17-dihydro gibberellins and related compounds on stem elongation and flowering inLolium temulentum
✍ Scribed by L. T. Evans; R. W. King; L. N. Mander; R. P. Pharis; K. A. Duncan
- Book ID
- 104657666
- Publisher
- Springer-Verlag
- Year
- 1994
- Tongue
- English
- Weight
- 775 KB
- Volume
- 193
- Category
- Article
- ISSN
- 0032-0935
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✦ Synopsis
Plants of Lolium temulentum L. cv. Ceres grown under short days (SDs) can be induced to initiate inflorescences either by exposure to one long day (LD) or by single applications of some gibberellins (GAs), which also enhance the flowering response to one LD. Single doses of up to 25 gg per plant of C-16,17-dihydro-GA5 were about as effective as GAs for promoting flowering after one LD but inhibited stem elongation by up to 40% over three weeks. The promotion of flowering but not the inhibition of elongation by 16,17-dihydro-GA 5 was reduced in SDs or in LDs low in far-red (FR) radiation. With shoot apices cultured in vitro, 16,17-dihydro-GA5 was more florigenic than GA 3 for apices excised after one LD of 14 h or more, but less florigenic for apices excised from plants in shorter days. 16,17-Dihydro-GA 5 was ineffective compared with GA1, GA 3 and GAs for ~-amylase production by half-seeds of Lolium, a response concordant with its effect on stem elongation. As with GAs, 16,17-dihydro derivatives of GA1, GA3, GA2o and several other GAs were more effective for flowering and less effective for stem elongation than the GAs from which they were derived. Hydroxylation at C-17 and/or C-16 generally reduced the effectiveness of 16,17-dihydro-GA5 for flowering. These results extend the known features of GA structure which favour flowering relative to stem elongation in L. temulentum. Moreover, C-16,17-dihydro-GA5 mimics, in its daylength-and wavelength-dependence and lack of stem elongation, characteristics of the LD stimulus in L. temulentum.