Effects of red light on gibberellin 3β-hydroxylase gene expression in dark-grown seedlings of dwarf and tall cultivars of Pisum sativum

Summary The changes in growth and gene expression of gibberellin (GA) 3β-hydroxylase were determined in dark-grown, 6-day-old, tall (cv. Alaska) and dwarf (cv. Progress No. 9) pea ( Pisum sativum L.) seedlings after transfer to conditions of red light irradiation. Red light inhibited the shoot elongation of Progress No. 9 much more so than that of Alaska, and the elongation of Progress No. 9 during 48 h was 23 percnt; that of Alaska. The transcript level of the GA 3β-hydroxylase gene was slightly greater in the shoots of dark-grown Alaska than that of dark-grown Progress No. 9. The red light decreased the transcript levels in both cultivars and the levels at 48 h were about 50 percnt; and 60 percnt; compared to the initial levels for Alaska and Progress No. 9, respectively. These results indicate that the difference in the transcript levels in both cultivars is not apparent. The only difference in GA 3β-hydroxylase proteins between Alaska and Progress No. 9 was the replacement of alanine with threonine at position 229 in their amino acid residues, which may affect the activity of the enzyme and may, at least partially, contribute to the growth habits of those cultivars. A possibility of additional function to distinguish the growth habits of those cultivars is also discussed here.