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Synthetic hexaploid wheat (SHW) represents a valuable source of new resistances to a range of biotic and abiotic stresses. A recombinant inbred line (RIL) population with 127 recombinant inbred lines derived from a SHW-derived variety Chuanmai 42 crossing with a Chinese spring wheat variety Chuannong 16 was used to map QTLs for agronomic traits including grain yield, grains per square meter, thousand-kernel weight, spikes per square meter, grain number per spike, grains weight per spike, and biomass yield. The population was genotyped using 184 simple-sequence repeat (SSR) markers and 34 sequence-related amplified polymorphism (SRAP) markers. Of 76 QTLs (LOD>2.5) identified, 42 were found to have a positive effect from Chuanmai 42. The QTL QGy.saas-4D.2 associated with grain yield on chromosome 4D was detected in four of the six environments and the combined analysis, and the mean yield, across six environments, of individuals carrying the Chuanmai 42 allele at this locus was 8.9% higher than that of those lines carrying the Chuannong 16 allele. Seven clusters of the yield-coincident QTLs were detected on 1A, 4A, 3B, 5B, 4D, and 7D.

Synthetic hexaploid wheat (SHW), a carrier of multiple elite genes, is an important genetic resource in improvement of common wheat (Triticum aestivum L.). Chuanmai 42 is a wheat cultivar with high-yield potential and resistance to strip rust (Puccinia striiformis f. sp. tritici), which was developed by crossing and backcrossing Syn769 (an elite synthetic hexaploid wheat) with Sichuan commercial wheat cultivars. For understanding the genetic effects of the introgression loci from SHW in Chuanmai 42, a total of 78 introgression loci of SHW were tested in Chuanmai 42 using 1029 simple sequence repeat (SSR) markers. Using 127 recombinant inbred lines (RILs, F8) in Chuanmai 42 (introgression loci) and Chuannong 16 (Chuannong 16 loci) backgrounds, the genetic effects of the introgression loci were evaluated across 6 environments in Sichuan Province, China from 2006 to 2009. One locus from the SHW parent, Barc1183, was detected in Chuanmai 42. It was located on the long arm of chromosome 4D after idenfication using the 4DS and 4DL telosomic lines of Chinese Spring and the 4D(4A) and 4D(4B) substitution lines of Longdon (T. turgidum subsp. durum). This locus had positive effects on increasing tiller number per plant, number of effective spikes, grains per square meter, harvest index, and grain production rate. The average yield of the 6 growing environments was increased by 8.9% when comparing locus Barc1183 in Chuanmai 42 to that in Chuannong 16. Therefore, Barc1183 from SHW is a candidate locus in high-yield breeding of wheat.

Genetic diversity and relationships of wild goat grass ( Aegilops tauschii Cosson) from Iran and Xinjiang, west China, as well as its weedy type from the Yellow River region of Shaanxi and Henan provinces in China were analyzed by simple sequence repeat (SSR) fingerprints. A high level of genetic diversity in Aegilops tauschii accessions from Iran was observed, and the richness of genetic diversity was followed by accessions from Shaanxi, Henan, and Xinjiang. The weedy type of Aegilops tauschii showed a close genetic relationship with the wild type from different regions in Iran. The results indicated that the weedy Aegilops tauschii found in the Yellow River region was most likely introduced from Iran—the diversity center of Aegilops tauschii . The weedy Aegilops tauschii populations found in the Yellow River region may be brought into the central part of China as a weed species together with common wheat ( Triticum aestivum L.) from the West during various periods of time in history. This finding has provided strong evidence for the introduction of common wheat from the West into China via the Silk Road, and also demonstrated the important role of the Silk Road in the exchange of agriculture and other relevant technologies between China and the West.

Synthetic hexaploid wheat (Triticum turgidumxAegilops tauschii) was created to explore for novel genes from T. turgidum and Ae. tauschii that can be used for common wheat improvement. In the present paper, research advances on the utilization of synthetic hexaploid wheat for wheat genetic improvement in China are reviewed. Over 200 synthetic hexaploid wheat (SHW) accessions from the International Maize and Wheat Improvement Centre (CIMMYT) were introduced into China since 1995. Four cultivars derived from these, Chuanmai 38, Chuanmai 42, Chuanmai 43 and Chuanmai 47, have been released in China. Of these, Chuanmai 42, with large kernels and resistance to stripe rust, had the highest average yield (>6 t/ha) among all cultivars over two years in Sichuan provincial yield trials, outyielding the commercial check cultivar Chuanmai 107 by 22.7%. Meanwhile, by either artificial chromosome doubling via colchicine treatment or spontaneous chromosome doubling via a union of unreduced gametes (2n) from T. turgidum-Ae. tauschii hybrids, new SHW lines were produced in China. Mitotic-like meiosis might be the cytological mechanism of spontaneous chromosome doubling. SHW lines with genes for spontaneous chromosome doubling may be useful for producing new SHW-alien amphidiploids and double haploid in wheat genetic improvement.