Present address: School of Agriculture and Food Science, University of Queensland, Brisbane, Qld 4072, Australia.
A combined biochemical screen and TILLING approach identifies mutations in Sorghum bicolor L. Moench resulting in acyanogenic forage production
Article first published online: 31 AUG 2011
© 2011 The Authors. Plant Biotechnology Journal © 2011 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd
Plant Biotechnology Journal
Volume 10, Issue 1, pages 54–66, January 2012
How to Cite
Blomstedt, C. K., Gleadow, R. M., O’Donnell, N., Naur, P., Jensen, K., Laursen, T., Olsen, C. E., Stuart, P., Hamill, J. D., Møller, B. L. and Neale, A. D. (2012), A combined biochemical screen and TILLING approach identifies mutations in Sorghum bicolor L. Moench resulting in acyanogenic forage production. Plant Biotechnology Journal, 10: 54–66. doi: 10.1111/j.1467-7652.2011.00646.x
- Issue published online: 6 DEC 2011
- Article first published online: 31 AUG 2011
- Received 24 May 2011; revised 16 June 2011; accepted 17 June 2011.
- cyanide toxicity;
- gene regulation;
- nitrogen metabolism;
- Sorghum bicolor
Cyanogenic glucosides are present in several crop plants and can pose a significant problem for human and animal consumption, because of their ability to release toxic hydrogen cyanide. Sorghum bicolor L. contains the cyanogenic glucoside dhurrin. A qualitative biochemical screen of the M2 population derived from EMS treatment of sorghum seeds, followed by the reverse genetic technique of Targeted Induced Local Lesions in Genomes (TILLING), was employed to identify mutants with altered hydrogen cyanide potential (HCNp). Characterization of these plants identified mutations affecting the function or expression of dhurrin biosynthesis enzymes, and the ability of plants to catabolise dhurrin. The main focus in this study is on acyanogenic or low cyanide releasing lines that contain mutations in CYP79A1, the cytochrome P450 enzyme catalysing the first committed step in dhurrin synthesis. Molecular modelling supports the measured effects on CYP79A1 activity in the mutant lines. Plants harbouring a P414L mutation in CYP79A1 are acyanogenic when homozygous for this mutation and are phenotypically normal, except for slightly slower growth at early seedling stage. Detailed biochemical analyses demonstrate that the enzyme is present in wild-type amounts but is catalytically inactive. Additional mutants capable of producing dhurrin at normal levels in young seedlings but with negligible leaf dhurrin levels in mature plants were also identified. No mutations were detected in the coding sequence of dhurrin biosynthetic genes in this second group of mutants, which are as tall or taller, and leafier than nonmutated lines. These sorghum mutants with reduced or negligible dhurrin content may be ideally suited for forage production.