Yong Zhou1, Hao Tang1, Meng-Ping Cheng1, Kwame O. Dankwa1, Zhong-Xu Chen1, Zhan-Yi Li1, Shang Gao1, Ya-Xi Liu1, Qian-Tao Jiang1, Xiu-Jin Lan1, Zhi-En Pu1, Yu-Ming Wei1, You-Liang Zheng1,2, Lee T. Hickey3 and Ji-Rui Wang1*
1 Triticeae Research Institute, Sichuan Agricultural University, Chengdu, China
2 Ministry of Education
Key Laboratory for Crop Genetic Resources and Improvement in Southwest
China, Sichuan Agricultural University, Ya’an, China
3 Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, QLD, Australia
* Corresponding author
Front. Plant Sci., 06 April 2017 | https://doi.org/10.3389/fpls.2017.00401
Abstract
Pre-harvest sprouting
(PHS) is mainly caused by the breaking of seed dormancy in high rainfall
regions, which leads to huge economic losses in wheat. In this study,
we evaluated 717 Chinese wheat landraces for PHS resistance and carried
out genome-wide association studies (GWAS) using to 9,740 DArT-seq and
178,803 SNP markers. Landraces were grown across six environments in
China and germination testing of harvest-ripe grain was used to
calculate the germination rate (GR) for each accession at each site. GR
was highly correlated across all environments. A large number of
landraces (194) displayed high levels of PHS resistance (i.e., mean GR
< 0.20), which included nine white-grained accessions. overall, white-grained accessions displayed a significantly higher mean gr (42.7–79.6%) compared to red-grained accessions (19.1–56.0%) across the six environments. landraces from mesic growing zones in southern china showed higher levels of phs resistance than those sourced from xeric areas in northern and north-western china. three main quantitative trait loci (qtl) were detected by gwas: one on 5d that appeared to be novel and two co-located with the grain color transcription factor tamyb10 on 3a and 3d. an additional 32 grain color related qtl (gcr-qtl) were detected when the set of red-grained landraces were analyzed separately. gcr-qtl occurred at high frequencies in the red-grained accessions and a strong correlation was observed between the number of gcr-qtl and gr (r2="0.62)." these additional factors could be critical for maintaining high levels of phs resistance and represent targets for introgression into white-grained wheat cultivars. further, investigation of the origin of haplotypes associated with the three main qtl revealed that favorable haplotypes for phs resistance were more common in accessions from higher rainfall zones in china. thus, a combination of natural and artificial selection likely resulted in landraces incorporating phs resistance in china.