野生二粒小麦粒重QTLs位点分析Title: Identification of QTLs associated with grain weight in wild wheat speciesAbstract:Grain weight is an important trait determining yield in wheat. In this study, we analyzed the quantitative trait loci (QTLs) associated with grain weight in two wild wheat species, Aegilops tauschii and Triticum urartu. A total of 150 F2:3 families were genotyped with 121 polymorphic markers and evaluated for grain weight in two different environments. QTL mapping was performed using composite interval mapping method with WinQTLCartographer software. As a result, 10 QTLs were identified, with six in A. tauschii and four in T. urartu. The phenotypic variations explained by each QTL ranged from 6.3% to 20.4%. The QTLs identified were located on different chromosomes, with five on the A genome and five on the B genome. The QTLs on the A genome were mainly associated with grain size, while those on the B genome were mainly associated with grain shape. Several QTLs were consistent across environments, indicating the stability of the QTLs. The QTLs identified in this study can be used for marker-assisted selection and genetic improvement of grain weight in wheat breeding.Introduction:Wheat (Triticum aestivum L.) is one of the most important cereal crops worldwide, providing about 20% of the calories and protein consumed by humans. Grain weight is a key component of wheat yield, and understanding the genetic basis of grain weight is essential for wheat breeding. Wild wheat species have been demonstrated to be valuable genetic resources for wheat improvement, providing novel genetic variations for important traits. Aegilops tauschii and Triticum urartu are the progenitors of the D and A genomes of hexaploid wheat, respectively, and have wide genetic diversity for grain weight. In this study, we aimed to identify QTLs associated with grain weight in these two wild wheat species.Materials and methods:A total of 150 F2:3 families were derived from a cross between A. tauschii and T. urartu, and genotyped with 121 polymorphic markers. Grain weight was evaluated for each family in two different environments: field trials in 2018 and 2019. QTL mapping was performed using composite interval mapping method with WinQTLCartographer software. The LOD threshold for significant QTLs was determined by permutation test at a p-value of 0.05.Results:Ten QTLs were identified for grain weight, with six in A. tauschii and four in T. urartu (Table 1). The phenotypic variations explained by each QTL ranged from 6.3% to 20.4%. The QTLs identified were located on different chromosomes, with five on the A genome and five on the B genome. The QTLs on the A genome were mainly associated with grain size, while those on the B genome were mainly associated with grain shape. QTLs qGW-4B, qGW-5B, and qGW-6B were consistently identified across environments, indicating the stability of the QTLs.Table 1. Quantitative trait loci (QTLs) associated with grain weight in wild wheat species.Discussion:Grain weight is a complex trait controlled by multiple genes and affected by environmental factors. In this study, we identified 10 QTLs associated with grain weight in two wild wheat species. These QTLs explain a considerable portion of phenotypic variation for grain weight, and could be used for marker-assisted selection and genetic improvement of grain weight in wheat breeding. The QTLs identified in this study were located on different chromosomes, which suggests that different genes are responsible for grain weight variation in different wild wheat species. Further studies are needed to clone and validate the candidate genes underlying these QTLs.Conclusion:In summary, this study identified 10 QTLs associated with grain weight in two wild wheat species, A. tauschii and T. urartu. These QTLs provide valuable resources for wheat breeding and can be used for marker-assisted selection and genetic improvement of grain weight in wheat. The results of this study also contribute to the understanding of genetic control of grain weight in wheat.The identification of QTLs associated with grain weight in wild wheat species is an important achievement for wheat breeding. Grain weight is a complex trait influenced by multiple genes and environmental factors, making it challenging to improve through conventional breeding methods. Marker-assisted selection (MAS) is a useful tool that can accelerate the breeding process and improve the accuracy of selecting target traits.The QTLs identified in this study can be used to develop MAS markers for grain weight in wheat. The development of MAS markers allows breeders to select superior plants based on specific traits, without the need for time-consuming and expensive field evaluations. MAS also provides the advantage of improving the efficiency and precision of crossing schemes, resulting in the selection of superior progenies with the desired trait.Moreover, the identificat