Abstract
The seed dormancy characteristic is regarded as one of the most critical factors for pre-harvest sprouting (PHS) resistance. As a wild wheat relative species, Aegilops tauschii is a potential genetic resource for improving common wheat. In this study, an advanced backcross population (201 strains) containing only Ae. tauschii segments was developed by means of synthetic octaploid wheat (hexaploid wheat Zhoumai 18 × Ae. tauschii T093). Subsequently, seed dormancy rate (Dor) in the advanced backcross population was evaluated on the day 3, 5 and 7, in which 2 major QTLs (QDor-2D and QDor-3D) were observed on chromosomes 2D and 3D with phenotypic variance explained values (PVEs) of 10.25 and 20.40%, respectively. Further investigation revealed significant correlation between QDor-3D and Tamyb10 gene, while no association was found between the former and TaVp1 gene, implying that QDor-3D site could be of closer position to Tamyb10. The obtained quantitative trait locus sites (QTLs) in this work could be applied to develop wheat cultivars with PHS resistance.
Highlights
As a serious natural disaster, pre-harvest sprouting (PHS) is featured by seed germination occurring in spikes before wheat harvest (Sharma et al, 1994), leading to consumption of seed storage material, reduction of grain weight as well as degradation of nutrition and processing quality (Groos et al, 2002)
Resistance to PHS is known to be linked to multi-factors including seed coat color, seed dormancy time, spike characteristics, germination inhibition substances of glume, alpha amylase activity, abscisic acid (ABA), and gibberellic acid (GA), etc., among which seed dormancy characteristic is regarded as one of the most critical factors for PHS resistance (Mares and Mrva, 2001; Gatford et al, 2002; Kottearachchi et al, 2006; Tan et al, 2006; Munkvold et al, 2009; Liu et al, 2017)
Polymorphism between the two parents was detected in 374 simple sequence repeat (SSR) markers, in which 104 of them were confirmed to be polymorphic in the advanced backcross population, accounting for 27.8%, with an average of 14.9 markers for each chromosome (Table 1)
Summary
As a serious natural disaster, pre-harvest sprouting (PHS) is featured by seed germination occurring in spikes before wheat harvest (Sharma et al, 1994), leading to consumption of seed storage material, reduction of grain weight as well as degradation of nutrition and processing quality (Groos et al, 2002). In China, PHS has caused severe damage in many areas including the middle and lower reaches of the Yangtze river, southwest winter wheat and northeast spring wheat regions, due to conventional abundant rains in harvest season (Xiao et al, 2002). This situation has occasionally happened in the Huanghuai and north winter wheat regions in recent years. TaVp1 and Tamyb genes for PHS resistance have been identified in bread wheat, which are located on the long arms of chromosomes 3A, 3B, and 3D, respectively (Xia et al, 2009; Himi et al, 2011; Sun et al, 2012). PHS resistance is closely related with the red pigmentation, which could be possibly attributed to the pleiotropic effect of this gene (Himi et al, 2002)
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