Thioredoxin h overexpressed in barley seeds enhances selenite resistance and uptake during germination and early seedling development |
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Authors: | Kim Yong-Bum Garbisu Carlos Pickering Ingrid J Prince Roger C George Graham N Cho Myeong-Je Wong Joshua H Buchanan Bob B |
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Institution: | (1) Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, Berkeley, CA 94720, USA;(2) Stanford Synchrotron Radiation Laboratory, SLAC MS 69, 2575 Sand Hill Road, Menlo Park, CA 94025, USA;(3) ExxonMobil Research and Engineering Co., Annandale, NJ 08801, USA;(4) Present address: Dpto. Agrosistemas y Producción Animal, Instituto Vasco de I+D Agrario, NEIKER, A.B.C/Berreaga, 48160 Derio, Spain;(5) Present address: Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan, S7N 5E2, Canada;(6) Present address: Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, Saskatchewan, S7N 5E2, Canada |
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Abstract: | The uptake, distribution and metabolism of selenite were examined in germinating homozygous barley (Hordeum vulgare L.) grain with thioredoxin h overexpressed in starchy endosperm. Results were related to the null segregant in which the transgene had segregated out during crossing. Compared with the null segregant, the homozygote showed enhanced germination and root and shoot growth in the presence of 1 and 2 mM sodium selenite. The rate of incorporation of selenite by the homozygote was approximately twice that of the null segregant. Based on X-ray absorption spectroscopy, the major products in both cases were selenomethionine-like species and the red, monoclinic form of elemental selenium, a derivative not previously reported in green plants. Selenite and selenate made up the balance. The distribution of the products formed differed as to the tissue — root, shoot, aleurone, endosperm — but the ratios were similar in the homozygote and null segregant. The results provide evidence that, in addition to the accelerated germination observed previously in water, barley grain overexpressing thioredoxin h are resistant to the inhibitory effects of selenite. These properties raise the possibility that plants overexpressing thioredoxin h could find application in the remediation of polluted environments. |
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Keywords: | Hordeum vulgare Seed Selenium Thioredoxin h Transgenic barley X-ray absorption spectroscopy |
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