Journal Article

Genetic and physiological analysis of <i>Rht8</i> in bread wheat: an alternative source of semi-dwarfism with a reduced sensitivity to brassinosteroids

Debora Gasperini, Andy Greenland, Peter Hedden, René Dreos, Wendy Harwood and Simon Griffiths

in Journal of Experimental Botany

Published on behalf of Society for Experimental Biology

Volume 63, issue 12, pages 4419-4436
Published in print July 2012 | ISSN: 0022-0957
Published online June 2012 | e-ISSN: 1460-2431 | DOI: http://dx.doi.org/10.1093/jxb/ERS138

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Over the next decade, wheat grain production must increase to meet the demand of a fast growing human population. One strategy to meet this challenge is to raise wheat productivity by optimizing plant stature. The Reduced height 8 (Rht8) semi-dwarfing gene is one of the few, together with the Green Revolution genes, to reduce stature of wheat (Triticum aestivum L.), and improve lodging resistance, without compromising grain yield. Rht8 is widely used in dry environments such as Mediterranean countries where it increases plant adaptability. With recent climate change, its use could become increasingly important even in more northern latitudes. In the present study, the characterization of Rht8 was furthered. Morphological analyses show that the semi-dwarf phenotype of Rht8 lines is due to shorter internodal segments along the wheat culm, achieved through reduced cell elongation. Physiological experiments show that the reduced cell elongation is not due to defective gibberellin biosynthesis or signalling, but possibly to a reduced sensitivity to brassinosteroids. Using a fine-resolution mapping approach and screening 3104 F2 individuals of a newly developed mapping population, the Rht8 genetic interval was reduced from 20.5 cM to 1.29 cM. Comparative genomics with model genomes confined the Rht8 syntenic intervals to 3.3 Mb of the short arm of rice chromosome 4, and to 2 Mb of Brachypodium distachyon chromosome 5. The very high resolution potential of the plant material generated is crucial for the eventual cloning of Rht8.

Keywords: Adaptation, brassinosteroid, height, Rht8, wheat

Journal Article.  12947 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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