JXB Advance Access published online on July 2, 2004
Journal of Experimental Botany, doi:10.1093/jxb/erh198
© 2004 by Oxford University Press
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1 CSIRO Plant Industry, GPO Box 1600 Canberra ACT 2601, Australia; Research School of Biological Sciences, GPO Box 475, Canberra, ACT 2601, Australia
* To whom correspondence should be addressed. E-mail: Linda.Tabe{at}csiro.au.
In order to increase the concentration of the nutritionally essential sulphur amino acids in seed protein, a transgene encoding a methionine- and cysteine-rich protein, sunflower seed albumin (SSA), was transferred to chickpeas (Cicer arietinum L). Transgenic seeds that accumulated SSA contained more methionine and less oxidized sulphur than the controls, suggesting that additional demand for sulphur amino acids from the expression of the transgene stimulated sulphur assimilation. In addition, the activity of trypsin inhibitors, a known family of endogenous, sulphur-rich chickpea seed proteins, was diminished in transgenic, SSA-containing seeds compared with the non-transgenic controls. Together, these results indicate that the reduced sulphur sequestered into SSA was supplied partly by additional sulphur assimilation in the developing transgenic seeds, and partly by some diversion of sulphur amino acids from endogenous seed proteins. Growth of chickpeas on nutrient with a high sulphur-to-nitrogen ratio increased the total seed sulphur content and the accumulation of sulphur amino acids in the seeds, and partly mitigated the effect of SSA accumulation on the trypsin inhibitor amount. The results suggest that free methionine and O-acetylserine (OAS) acted as signals that modulated chickpea seed protein composition in response to the variation in sulphur demand, as well as in response to variation in the nitrogen and sulphur status of the plant.
Accepted May 10, 2004
Sulphur Metabolism Special Issue Article
Sulphur and nitrogen nutrition influence the response of chickpea seeds to an added, transgenic sink for organic sulphur
2 Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589, Japan; Present address: Department of Genetics, Development and Cell Biology, lowa State University, Ames, lowa 50011, USA
3 CSIRO Plant Industry, GPO Box 1600 Canberra ACT 2601, Australia
4 Research School of Biological Sciences, GPO Box 475, Canberra, ACT 2601, Australia
5 Biotechnology Research Center, University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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