Malting quality and preharvest sprouting traits are genetically correlated in spring malting barley

Abstract

Key message Malt for craft “all-malt” brewing can have high quality, PHS resistance, and malted in normal timeframes. Canadian style adjunct malt is associated with PHS susceptibility. Abstract Expansion of malting barley production into non-traditional growing regions and erratic weather has increased the demand for preharvest sprouting (PHS) resistant, high quality malting barley cultivars. This is hindered by the relatively unknown relationships between PHS resistance and malting quality. Here we present a three-year study of malting quality and germination at different after-ripening durations post physiological maturity. Malting quality traits alpha amylase (AA) and free amino nitrogen (FAN) and germination rate at six days post PM shared a common association with a SNP in HvMKK3 on chromosome 5H in the Seed Dormancy 2 (SD2) region responsible for PHS susceptibility. Soluble protein (SP) and soluble over total protein (S/T) both shared a common association with a marker in the SD2 region. Significant genetic correlations between PHS resistance and the malting quality traits AA, FAN, SP, S/T were detected across and within HvMKK3 allele groups. High adjunct malt quality was related to PHS susceptibility. Selection for PHS resistance led to a correlated response in malting quality traits. Results strongly suggest pleiotropy of HvMKK3 on malting quality traits and that the classic “Canadian-style” malt is caused by a PHS susceptible allele of HvMKK3. PHS susceptibility appears to benefit the production of malt intended for adjunct brewing, while PHS resistance is compatible with all-malt brewing specifications. Here we present our analysis on the effect of combining complexly inherited and correlated traits with contrasting goals to inform breeding practice in malting barley, the general principles of which can be extended to other breeding programs.

Identification of novel loci regulating dormancy in barley and association with hypoxia sensitivity

“…Previous work has identified the SD1 and SD2 loci as major effect QTLs associated with seed dormancy in multiple barley populations, highlighting the importance of the underlying alanine aminotransferase (AlaAT1, SD1) and MAPK kinase 3 (MKK3, SD2) across multiple barley germplasms (Li et al, 2003;Hori et al, 2007;Ullrich et al, 2009;Nakamura et al, 2017). The SD2 locus is associated with low dormancy at maturity, favorable malt quality, and high PHS susceptibility, with several recent studies suggesting that pleiotropy rather than linkage may be causing this association (Sweeney et al, 2022;Rooney et al, 2023). The alanine aminotransferase1 gene (AlaAT1) in the SD1 locus influences variation in dormancy at maturity, and its impact on dormancy increases during after-ripening (Romagosa et al, 1999;Vetch et al, 2020).…”