Abstract: 【Objective】Pre-harvest sprouting (PHS) is a serious limiting factor for wheat (Triticum aestivum L.) grain yield and end-use quality. Synthetic hexaploid wheats (SHW) and wheat landraces (WL) are important germplasm resources for improving PHS resistance in wheat. The objective of this study is to utilize PHS-resistant loci from SHW and WL for breeding PHS-resistant elite materials, which will provide a theoretical basis for improving PHS resistance of wheat cultivars.【Method】In this study, SYN792 (a Synthetic hexaploid wheat from CIMMYT) and Fulingxuxumai (a Chinese wheat landrace) were used as female parents to cross and backcross with Chuanmai 45 (a sensitive variety to PHS), respectively. Two BC₁F₇ populations including 1796 lines were established. Seed germination index (GI) and seed germination rate of in each spike (SGR) in different environments were used to evaluate PHS resistance. Two germination temperature of 25℃ (18GI) and 32℃ (19GI) were set to examine seed germinability in 2018 and 2019. 1796 BC₁F₇ lines were evaluated preliminarily by SGR phenotype and molecular markers detection in 2017, and the introgression lines with PHS-3D and PHS-A1 resistant loci and SGR less than 35% were screened. Introgression lines with PHS-3D and PHS-A1 resistant loci were used to analyze utilization efficiency of SHW and WL in PHS-resistance breeding by identifying PHS-resistance and yield related traits in 2018 and 2019.【Result】PHS resistance of 1796 lines was evaluated preliminarily, and 537 lines with SGR value less than 35% were screened for further molecular marker detection. A total of 332 lines with PHS-3D and PHS-A1 were selected by SSR marker, and the frequency of WL introgression lines was significantly higher than that of SHW introgression lines. 332 introgression lines were used to analysis PHS-resistance and yield related traits in 2018 and 2019. There was a significant positive correlation between different PHS indexes in different years, but there was no significant difference in the values of 18GI, 18SGR and 19SGR between SHW and WL introgression lines. The average values of 18SGR, 19SGR and 18GI in SHW and WL introgression lines were lower than 23%. As far as GI value is concerned, there is obvious difference between different germination temperatures. At the germination temperature of 32℃, the mean 19GI value of SHW PHS-3D introgression lines was significantly lower than that of WL PHS-A1 introgression lines. Grain color was associated with PHS resistance in SHW introgression lines, and the red-grained SHW introgression lines had lower the mean GI and SGR values than the white-grained lines. Among 73 SHW introgression lines, 11 white-grained lines showed medium or higher resistance to PHS，and the GI values of 14 red-grained lines at different germination temperatures were lower than 35%. According to the data of agronomic traits in 2018 and 2019, thousand grain weight of SHW introgression lines was significantly higher than that of WL introgression lines, but the number of grains per spike was significantly lower than that of WL introgression lines. 23 elite introgression lines including seven SHW introgression lines and 16 WL introgression lines were selected. Two SHW white-grained introgression lines had better resistance to PHS, and the GI values of two red-grained introgression lines at different germination temperatures were lower than 25%.【Conclusion】It is feasible to transfer PHS-3D and PHS-A1 resistance loci to PHS from SHW and WL for improving PHS-resistance of modern wheat cultivars. In this study, the breeding efficiency of WL for PHS-resistance is better than that of SHW. However, the stability of PHS-resistance of SHW introgression lines was better than that of WL introgression lines. 23 SHW and WL elite introgression lines could be used as parents to improve the PHS-resistance and yield traits in wheat. In particular, the white-grained SHW introgression line No.5201 and the red-grained SHW introgression lines No.5497 and No.5505 were very valuable parents for wheat breeding of PHS resistance.  

Key words: wheat, synthetic hexaploid wheat (SHW), wheat landraces, pre-harvest sprouting (PHS), yield related yield