Growth and gibberellin-A1metabolism in normal and gibberellin-insensitive (Rht3) wheat (Triticum aestivumL.) seedlings
✍ Scribed by John L. Stoddart
- Publisher
- Springer-Verlag
- Year
- 1984
- Tongue
- English
- Weight
- 683 KB
- Volume
- 161
- Category
- Article
- ISSN
- 0032-0935
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✦ Synopsis
Growth parameters were determined for tall (rht3) and dwarf (Rht3) seedlings of wheat (Triticum aestivum L.). Plant statures and leaf length were reduced by 50% in dwarfs but root and shoot dry weights were less affected. Leaves of dwarf seedlings had shorter epidermal cells and the numbers of cells per rank in talls and dwarfs matched the observed relationships in overall length. Talls grew at twice the rate of dwarfs (2.3 compared with 1.2 mm h-l). [3H]Gibberellin A 1 ([3H]GA1) was fed to seedlings via the third leaf and metabolism was followed over 12 h. Immature leaves of tall seedlings transferred radioactivity rapidly to compounds co-chromatographing with [3H]gibberellin A 8 ([3H]GA8) and a conjugate of [3H]GA8, whereas leaves of dwarf seedlings metabolised [3H]GA1 more slowly. Roots of both genotypes produced [3H]GA8-1ike material at similar rates. Isotopic dilution studies indicated a reduced 2fl-hydroxylation capacity in dwarfs, but parallel estimates of the endogenous GA pool size, obtained by radioimmunoassay, indicated a 12-15 times higher level of GA in the dwarf immature leaves. Dwarfing by the Rht3 gene does not appear to operate through enhanced, or abnormal metabolism of active gibberellins and the act of GA metabolism does not bear an obligate relationship to the growth response.