The 'green revolution' refers to the development of improved crops, such as the high-yield semi-dwarf (sd) rice variant called IR8 that saved the world from a chronic food shortage in the 1960s. In the April 18 Nature, Sasaki et al. describe the molecular characterization of the IR8 variant (Nature 2002, 416:701-702).

Mutation of the sd1 gene is the reason for IR8's short stature. Sasaki et al. report that sd1 encodes an oxidase enzyme involved in the biosynthesis of the plant hormone gibberellin. They found that sd1 mutants respond to gibberellin and resume normal growth. The IR8 plants had reduced levels of gibberellin precursors, implicating the GA20ox oxidase in the reduced gibberellin biosynthesis.

They identified a new GA20ox gene and detected a deletion associated with the reduced semi-dwarf phenotype; the wild-type GA20ox-2 gene could rescue sd1 mutations. They conclude that the SD1...

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