PT  - JOURNAL ARTICLE
AU  - Foster, K. R.
AU  - Morgan, P. W.
TI  - Genetic Regulation of Development in Sorghum bicolor (IX. The ma3R Allele Disrupts Diurnal Control of Gibberellin Biosynthesis)
AID  - 10.1104/pp.108.1.337
DP  - 1995 May 01
TA  - Plant Physiology
PG  - 337--343
VI  - 108
IP  - 1
4099  - http://www.plantphysiol.org/content/108/1/337.short
4100  - http://www.plantphysiol.org/content/108/1/337.full
SO  - Plant Physiol.1995 May 01; 108
AB  - The diurnal regulation of gibberellin (GA) concentrations in Sorghum bicolor was studied in a mutant lacking a light-stable 123-kD phytochrome (ma3Rma3R), wild-type (ma3ma3,Ma3Ma3), and heterozygous (ma3ma3R) cultivars. GAs were determined in shoots of 14-d-old plants by gas chromatography-selected ion-monitoring-mass spectrometry. GA12 levels fluctuated rhythmically in Ma3Ma3, ma3ma3, and ,ma3Rma3R; Peak levels occured 3 to 9 h after lights-on. In some experiments, GA53 levels followed a similar pattern. There was no rhythmicity in levels of GA19 and GA8 in any genotype. In ma3ma3 and Ma3Ma3, GA20 levels increased at lights-on, peaked in the afternoon, and decreased to minimum levels in darkness. In ma3Rma3R, peak GA20 levels occured at lights-on, 9 h earlier than in the wild-type genotypes. The pattern for GA1 levels closely followed GA20 levels in all cultivars. One copy of ma3 restored near wild-type regulation of GA20 levels. GA rhythms persisted in 25-d-old ma3ma3 plants. Since absence of the 123-kD phytochrome disrupted diurnal regulation of the GA19 -> GA20 step, the ma3Rma3R genotype may be viewed as being phase shifted in the rhythmic levels of GA20 and GA1 rather than as simply overproducing them.