Nature Biotechnology
19, 466 - 469 (2001)
doi:10.1038/88143
Enhanced tolerance of rice to low iron availability in alkaline soils using barley nicotianamine aminotransferase genesMichiko Takahashi1, 2, Hiromi Nakanishi1, Shinji Kawasaki3, Naoko K. Nishizawa4
& Satoshi Mori1, 21
Laboratory of Plant Molecular Physiology, The University of Tokyo, Tokyo 113-8657, Japan. 2
CREST, Tsukuba 305-8602, Japan. 3
National Institute of Agrobiological Resources, Tsukuba 305-8602, Japan. 4
Laboratory of Plant Biotechnology, The University of Tokyo, Tokyo 113-8657, Japan.
Correspondence should be addressed to Satoshi Mori asmori@mail.ecc.u-tokyo.ac.jpOne of the widest ranging abiotic stresses in world agriculture arises from low iron (Fe) availability due to high soil pH, with 30% of arable land too alkaline for optimal crop production. Rice is especially susceptible to low iron supply, whereas other graminaceous crops such as barley are not. A barley genomic DNA fragment containing two naat genes, which encode crucial enzymes involved in the biosynthesis of phytosiderophores, was introduced into rice using Agrobacterium-mediated transformation and pBIGRZ1. Phytosiderophores are natural iron chelators that graminaceous plants secrete from their roots to solubilize iron in the soil. The two transgenes were expressed in response to low iron nutritional status in both the shoots and roots of rice transformants. Transgenic rice expressing the two genes showed a higher nicotianamine aminotransferase activity and secreted larger amounts of phytosiderophores than nontransformants under iron-deficient conditions. Consequently, the transgenic rice showed an enhanced tolerance to low iron availability and had 4.1 times greater grain yields than that of the nontransformant rice in an alkaline soil.
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