Quantitative trait loci associated with salinity tolerance in field grown bread wheat Jose ´ Luis Dı ´az De Leo ´n • Ricardo Escoppinichi • Nadia Geraldo • Thelma Castellanos • Abdul Mujeeb-Kazi • Marion S. Ro ¨der Received: 15 September 2010 / Accepted: 16 May 2011 / Published online: 1 June 2011 Ó Springer Science+Business Media B.V. 2011 Abstract The differential response to field salinity of the parents of the ITMI wheat mapping population (cv. Opata 85 and the synthetic hexaploid W7984) was exploited to perform a QTL analysis of the response to salinity stress of a set of agronomic traits over two seasons. The material was irrigated either with potable water (EC of 1.0 dS m -1 ) or with diluted seawater (12.0 dS m -1 ). Grain yield was positively correlated with tiller number, plant height, percentage survival, ear weight, ear length, grain number per ear, grain weight and thousand grain weight, and negatively with time to booting, anthesis and physiological maturity, under both the control and salinity stress treatments. In all, 22 QTL were detected under control conditions, and 36 under salinity stress. Of the latter, 13 were major loci (LOD [ 3.0) and eight were reproducible across both seasons. Chromosome 2D harboured 15 salinity stress associated QTL and chromosome 4A six such QTL. The remaining loci were located on chromosomes 2A, 5A, 6A, 7A, 1B, 4B, 3B, 6B, 7B and 6D. Keywords Wheat Á QTL Á Salinity stress Á Salinity Soil salinity impairs the growth and development of most plant species, including the leading arable crops (Greenway and Munns 1980; Yokoy et al. 2002). Worldwide, some 33% of arable land is affected by excessive sodium ions, 20% other cations, 26% by drought and 11% by flooding, leaving only 10% free of abiotic stress (Shannon 1982; Flowers and Yeo 1995). A degree of tolerance to salinity stress has been found in bread wheat germplasm, notably the landraces Shorawaki and Kharchia (Dı ´az De Leo ´n et al. 1995, 2000, 2001), and attempts have been made to use such landraces as parents in breeding programmes intended to produce tolerant cultivars of spring wheat (Ashraf and O’Leary 1996). A key tolerance-associated gene is Kna1, located on chromosome arm 4DL, which controls the ability to discriminate between the K ? and the Na ? ion (Gorham et al. 1987; Shah et al. 1987; Dubcovsky et al. 1996; Gao et al. 2001). Kna1 is present in the wheat D genome progenitor species Aegilops tauschii, but variation for K ? /Na ? discrim- ination has also been detected in durum wheat J. L. Dı ´az De Leo ´n (&) Á R. Escoppinichi Á N. Geraldo Universidad Autonoma de Baja California Sur, La Paz, Baja California Sur, Mexico e-mail: jldeleon@uabcs.mx T. Castellanos Centro de Investigaciones Biologicas (CIBNOR), La Paz, Baja California Sur, Mexico A. Mujeeb-Kazi Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT), El Bata ´n, Texcoco, Mexico M. S. Ro ¨der Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany 123 Euphytica (2011) 181:371–383 DOI 10.1007/s10681-011-0463-5