Expression of Aluminum Tolerance Transferred from Atlas 66 to Hard Winter Wheat

Abstract

Genetic improvement of acid soil tolerance of wheat (Triticum aestivum L.) adaptable to the Great Plains involves the transfer of AI tolerance from other gene pools. One hindrance may be the interaction of gene effect with genetic background. Aluminum‐tolerant nearisoĺines of hard red winter (HRW) wheat were selected on the basis of the hematoxylin assay using ‘Atlas 66’ as the source of tolerance. The objectives were to enumerate the genes for AI tolerance in these lines and to quantify their expression in artificial solution and natural soil media containing AI. Laboratory and growth chamber experiments were conducted with AI‐tolerant and AI‐susceptible near‐isolines of ‘Chisholm’ and ‘Century’. Segregation for hematoxylin staining score in populations derived from crossing the tolerant isoline with its recurrent parent indicated a single dominant gene was transferred from Atlas 66. This gene does not appear to be unique relative to ‘2180’. Dose‐response curves for relative root length (RRL) measured in solution culture confirmed differences in AI tolerance predicted by the hematoxylin assay. Each tolerant isoline showed a linear decline in RRL to increasing AI concentration (0.09–0.72 mM AI), while the susceptible isolines and recurrent parents showed a more acute curvilinear response. The tolerant isolines exceeded their recurrent parent by 19% (Chisholm) and 38% (Century) in RRL, measured in five acidic Appalachian soils. While the hematoxylin assay enabled selection of a dominant gene conferring increased root growth in response to AI, complete expression of tolerance from Atlas 66 was not achieved or was modified in these HRW backgrounds.