Abstract
Wheat landraces in Turkey are an important genetic resource for wheat improvement. An exhaustive 5-year (2009–2014) effort made by the International Winter Wheat Improvement Programme (IWWIP), a cooperative program between the Ministry of Food, Agriculture and Livestock of Turkey, the International Center for Maize and Wheat Improvement (CIMMYT) and the International Center for Agricultural Research in the Dry Areas (ICARDA), led to the collection and documentation of around 2000 landrace populations from 55 provinces throughout Turkey. This study reports the genetic characterization of a subset of bread wheat landraces collected in 2010 from 11 diverse provinces using genotyping-by-sequencing (GBS) technology. The potential of this collection to identify loci determining grain yield and stripe rust resistance via genome-wide association (GWA) analysis was explored. A high genetic diversity (diversity index = 0.260) and a moderate population structure based on highly inherited spike traits was revealed in the panel. The linkage disequilibrium decayed at 10 cM across the whole genome and was slower as compared to other landrace collections. In addition to previously reported QTL, GWA analysis also identified new candidate genomic regions for stripe rust resistance, grain yield, and spike productivity components. New candidate genomic regions reflect the potential of this landrace collection to further increase genetic diversity in elite germplasm.
Highlights
Wheat is an important crop in Turkey, planted on an area of more than 7 million ha with annual production exceeding 20 million tons
The old system of wheat diversity description used by Vavilov (Zuev et al, 2013) based on the similarity of highly inherited spike traits has accorded well with the genetic structuring of Turkish winter wheat landraces suggesting that spike morphology is one of the most important selection criterions adopted by farmers in Turkey
No epistatic interactions were observed between the stripe rust genes Yr29/Lr46 and Yr50 and any of the main effect markers which contrasts with the resistance mechanisms of e.g., the stem rust genes such as Sr2 (Singh et al, 2009). We successfully identified both known associations as well as new candidate genomic regions for both grain yield and spike productivity components and stripe rust resistance in the Turkish landrace panel
Summary
Wheat is an important crop in Turkey, planted on an area of more than 7 million ha with annual production exceeding 20 million tons (http://faostat.fao.org/). The center of wheat origin and diversity is in the Fertile Crescent, a geographic area known as the Cradle of Civilization, which encompasses several countries in the Middle East and part of modernday Turkey (Feldman, 2001). For this reason the diversity of wheat and its wild relatives in Turkey plays a global role as a significant genetic resource for wheat improvement (Karagöz, 2014). The main reasons for the farmers to maintain these historic landraces are their adaptability to mountainous areas and excellent quality for home use
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