GENETIC ENHANCEMENT FOR RESISTANCE TO BIOTIC AND ABIOTIC STRESSES IN HARD WINTER WHEAT
Location: Hard Winter Wheat Genetics Research Unit
Title: Mapping Quantitative Trait Loci for Long Coleoptile in Chinese Wheat Landrace Wangshuibai
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 12, 2009
Publication Date: January 1, 2010
Citation: Yu, J., Bai, G. 2010. Mapping Quantitative Trait Loci for Long Coleoptile in Chinese Wheat Landrace Wangshuibai. Crop Science. 50:59-66.
Interpretive Summary: In drought environments, longer coleoptile wheat is preferred because it can be sown deeply for better seedling establishment. Wangshuibai, a Chinese landrace, has a long coleoptile. A recombinant inbred population from a cross between Wangshuibai, and the short-coleoptile U.S. wheat cultivar, Wheaton, were used to identify genes for coleoptile length and plant height. Coleoptile length was a highly heritable trait. Six quantitative trait loci (QTL) were identified on chromosomes 1B, 3D, 4D, 5AS, and 5B for coleoptile length; four of them on 3D, 4D and 5AS also affected plant height. One QTL with a major effect on long coleoptile was mapped on the same chromosome location as gene Rht-D1 (Rht2), a gene for reduced height (Rht) on chromosome 4DS. Another QTL with a major effect on long coleoptiles was located on chromosome 4DL. The gene Rht-Dla from Wangshuibai appeared to affect expression of long coleoptile QTL on 4DL. Other QTL showed only minor effects. To select long coleoptile wheat cultivars with reduced plant height, the Rht-Dla from Wangshuibai can be used in combination with other gibberellic acid (GA)-sensitive Rht genes.
Wheat (Triticum aestivum L.) cultivars with long coleoptiles can be sown deeply for better seedling establishment in drought environments. A population of 139 recombinant inbred lines (RILs) from a cross between a long-coleoptile Chinese landrace, Wangshuibai, and short coleoptile U.S. wheat cultivar, Wheaton, were characterized for coleoptile length and plant height. Heritabilities for coleoptile length were high (h2> 0.82). Interval mapping identified six significant quantitative trait loci (QTL) on 1B, 3D, 4D, 5AS, and 5B for coleoptile length; four of them on 3D, 4D and 5AS showed pleiotropic effects on plant height. One major QTL for long coleoptile was mapped on the locus Rht-D1 (Rht2) for reduced height (Rht) on chromosome 4DS and explained up to 65% of phenotypic variation for coleoptile length. Another major QTL was located on 4DL and explained up to 33% of phenotypic variation for coleoptile length. Standard height allele Rht-Dla from Wangshuibai appeared to have an epistatic effect on the 4DL QTL for long coleoptile. Other QTL showed only minor effects. Although Rht-Dla explained a major portion of genetic variation for long coleoptile in Wangshuibai, a combination of Rht-D1a in Wangshuibai with gibberellic acid (GA)-sensitive Rht genes for reduced wheat height from other sources should be able to select long coleoptile semidwarf cultivars in wheat breeding programs for which long coleoptile is a breeding objective.