Zhou Yong, Tang Hao, Cheng Meng-Ping, Dankwa Kwame O, Chen Zhong-Xu, Li Zhan-Yi, Gao Shang, Liu Ya-Xi, Jiang Qian-Tao, Lan Xiu-Jin, Pu Zhi-En, Wei Yu-Ming, Zheng You-Liang, Hickey Lee T, Wang Ji-Rui
Triticeae Research Institute, Sichuan Agricultural UniversityChengdu, China.
Ministry of Education Key Laboratory for Crop Genetic Resources and Improvement in Southwest China, Sichuan Agricultural UniversityYa'an, China.
Front Plant Sci. 2017 Apr 6;8:401. doi: 10.3389/fpls.2017.00401. eCollection 2017.
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 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 ( = 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.
收获前发芽(PHS)主要是由高降雨地区种子休眠的打破引起的,这给小麦带来了巨大的经济损失。在本研究中,我们评估了717份中国小麦地方品种的PHS抗性,并使用9740个DArT-seq标记和178803个SNP标记进行了全基因组关联研究(GWAS)。地方品种在中国的六个环境中种植,并对收获成熟的籽粒进行发芽试验,以计算每个位点每个材料的发芽率(GR)。GR在所有环境中高度相关。大量地方品种(194个)表现出高水平的PHS抗性(即平均GR<0.20),其中包括9个白粒材料。总体而言,在六个环境中,白粒材料的平均GR(42.7 - 79.6%)显著高于红粒材料(19.1 - 56.0%)。来自中国南方湿润生长区的地方品种比来自中国北方和西北干旱地区的地方品种表现出更高水平的PHS抗性。通过GWAS检测到三个主要的数量性状位点(QTL):一个位于5D上,似乎是新发现的,另外两个与3A和3D上的粒色转录因子共定位。当单独分析红粒地方品种群体时,还检测到另外32个与粒色相关的QTL(GCR-QTL)。GCR-QTL在红粒材料中高频出现,并且观察到GCR-QTL的数量与GR之间存在很强的相关性(r = 0.62)。这些额外的因素对于维持高水平的PHS抗性可能至关重要,并代表了导入白粒小麦品种的目标。此外,对与三个主要QTL相关的单倍型起源的研究表明,在中国降雨较多地区的材料中,对PHS抗性有利的单倍型更为常见。因此,自然选择和人工选择的结合可能导致了中国地方品种中包含PHS抗性。