Preharvest sprouting quantitative trait loci (QTL) have been identified on each wheat chromosome. Preharvest sprouting is a complex, quantitative trait (reviewed by Mares & Mrva, 2014 Nakamura, 2018 Vetch et al., 2019b). This variation can largely be attributed to the genetic mechanisms that control dormancy (Biddulph et al., 2007 Nakamura, 2018). Montana-grown winter wheat cultivars vary greatly in PHS under similar conditions (Vetch et al., 2019a). The economic impacts paired with the need for stable food production highlight the value in identifying mechanisms that control PHS to allow selection of PHS-resistant cultivars (Briggle, 1980).Įnvironmental conditions play a primary role in the occurrence of PHS, not only does prolonged exposure to moisture between physiological maturity (when grain fill is complete and >80% of the peduncle on the plant has browned) and harvest trigger PHS but temperature during plant development (prior to grain maturity) has been demonstrated to impact PHS susceptibility (Biddulph et al., 2007 Nakamura et al., 2011 Jiménez et al., 2017). Wheat provides >20% of global human calorie intake and thus is important to global food security (FAOSTAT, 2011).
Products made from flour prepared from PHS-damaged grain are often porous, sticky, and darker in color. The germination process damages grain and makes it unsuitable for most end uses. Preharvest sprouting occurs periodically in many wheat growing regions worldwide and is responsible for large economic losses each year. Wheat ( Triticum aestivum L.) preharvest sprouting (PHS) happens when grains begin to germinate before harvest. Markers for both TaMFT-3A and TaMFT-3B2 should be used in selecting for increased wheat dormancy and PHS resistance. In the current study, the TaMFT-3A and TaMFT-3B2 alleles each explained 14% of observed PHS variation. Previous research has shown TaMFT-3A as having a large impact on PHS resistance. No association between PHS resistance and TaMKK3-4A or TaVp1-3B variation was observed, though Loma and Warhorse vary for TaMKK3-4A and TaVp1-3B mutations reported to be PHS associated. No sequence variation between Loma and Warhorse was detected in the exons of the TaMFT-B1 and D homeologs.
The PHS variation was associated with the TaMFT- A and the B2 homeolog with Loma carrying mutant forms of each gene. The 162 BC 1 DHL lines were grown over two field seasons and PHS susceptibility was assessed by measuring PHS resistance in physiologically mature heads. In this study, the TaMFT ( 3A, 3B1, 3B2, 3D), TaMKK3-4A, and TaVP1-3B genes were assessed for association with PHS in a double-haploid line (DHL) hard red winter wheat population derived from a BC 1 cross between the cultivars Loma and Warhorse, where Loma was the recurrent and PHS susceptible parent. Multiple genes involved in the development of seed dormancy are associated with PHS. Investigating the genetics that control PHS resistance may result in increased control of seed dormancy. The phenomenon of preharvest sprouting (PHS), caused by rain after physiological maturity and prior to harvest, negatively affects wheat ( Triticum aestivum L.) production and end use.
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