Published in:
The New Phytologist, 153 (2002) 1, Seite 73-80
Language:
English
ISSN:
0028-646X;
1469-8137
Origination:
Footnote:
Description:
• Sulphur export and redistribution from the cotyledons of pea (Pisum sativum) seedlings was investigated to determine the role of cotyledons as a sulphur source during root-shoot axis development. • Thiols and sulphate were analysed using standard biochemical techniques, and <sup>35</sup> S fed to cotyledons by injection. • After <sup>35</sup> S-cysteine injection, c. 50% of the labelled S in the cotyledon was metabolized to <sup>35</sup> S-sulphate. This reaction was partly inhibited by aminooxyacetic acid, an inhibitor of cysteine-desulfhydrase. After <sup>35</sup> S-sulphate application, c. 1% of the radiolabel was found in cysteine and glutathione in the cotyledon. After 2 h, c. 20% of the <sup>35</sup> S was transported into the root-shoot axis independently of whether <sup>35</sup> S-sulphate or <sup>35</sup> S-cysteine was injected into the cotyledon. After 4 h, 40% of <sup>35</sup> S was found outside the cotyledon. • Cotyledons of pea seedlings are capable of sulphate assimilation and cysteine degradation. Both sulphate and reduced sulphur were allocated from the cotyledons to the developing tissues of the pea seedlings.