Mutations in the <i>HvMKK3</i> and <i>HvAlaAT1</i> genes affect barley preharvest sprouting and after‐ripened seed dormancy

Vetch, Justin M.; Walling, Jason G.; Sherman, Jamie; Martin, John M.; Giroux, Michael J.

doi:10.1002/csc2.20178

Cited by 10 publications

(26 citation statements)

References 33 publications

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“…SD1 was initially identified as a seed dormancy QTL in barley by Oberthur et al. (1995) and its role in long‐term seed dormancy has been further examined by many authors (Han et al., 1999); Romagosa et al., 1999); Sato et al., 2016); Vetch et al., 2020). HvAlaAT1‐SD1 has not been observed to affect PHS when phenotyped within 7 d of PM (Ullrich et al., 2009; Vetch et al., 2020) but has been associated with GE at PM 7 (Bonnardeaux et al., 2008; Prada et al., 2004).…”

Section: Discussionmentioning

confidence: 99%

Interactions of the barley SD1 and SD2 seed dormancy loci influence preharvest sprouting, seed dormancy, and malting quality

et al. 2021

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Preharvest sprouting (PHS) can severely damage barley (Hordeum vulgare L.) malting quality and is of particular concern in locations with a high frequency of precipitation around harvest. Malting quality and PHS resistance are often negatively correlated, and the SD2 locus on chromosome 5H has been associated with both traits. Using three spring barley populations, PHS, seed dormancy, and germination rate were mapped over six time points to identify changes in genetic control of these traits during the after‐ripening period. HvAlaAT1 at the SD1 locus was associated with long‐term dormancy and reduced germination rate. Ninety lines were Sanger sequenced for HvGA20ox1, but variants were not associated with PHS or germination traits. The allelic state of HvMKK3 was strongly associated with genetic PHS susceptibility in North American spring two‐row barley germplasm and interactions between HvAlaAT1 and HvMKK3 were associated with changes in seed dormancy and germination rate over time. Several malting quality traits were associated with HvMKK3 alleles. Kompetitive allele‐specific polymerase chain reaction (KASP) markers were developed for the causal mutations in HvAlaAT1 and HvMKK3 and a diagnostic mutation in HvGA20ox1. Haplotypes with PHS resistance, short primary dormancy, and a high germination rate were identified that could be useful for breeding for PHS resistance and malting quality.

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Section: Discussionmentioning

confidence: 99%

Interactions of the barley SD1 and SD2 seed dormancy loci influence preharvest sprouting, seed dormancy, and malting quality

et al. 2021

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“…The EMS‐induced Qsd2 mutant has a different genetic background and the environmental conditions and methods used for its analysis were different from those used in our current work, so it is not possible to make an exact comparison, but the EMS mutant seems to have moderately prolonged dormancy compared with our qsd2 mutants in this study (Nakamura et al ., 2016 ). We hypothesize that barley cultivation and breeding have selected alleles with enhanced function at Qsd1 and Qsd2 to promote rapid germination, from the pool of natural alleles represented among barley cultivars (Nakamura et al ., 2016 ; Sato et al ., 2016 ; Vetch et al ., 2020 ). We attempted to break dormancy by using the high temperature of 40 °C for 4 weeks, with a dormant after‐ripening period of 10 weeks; however, even under these extreme conditions, the germination of all mutants was still significant delayed at 25 °C, thus preventing a comparative analysis of the individual contribution of Qsd1 and Qsd2 to dormancy (Figure 3 ).…”

Section: Discussionmentioning

confidence: 99%

Regulation of germination by targeted mutagenesis of grain dormancy genes in barley

Hisano

Hoffie

Abe

et al. 2021

Plant Biotechnology Journal

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Summary High humidity during harvest season often causes pre‐harvest sprouting in barley (Hordeum vulgare). Prolonged grain dormancy prevents pre‐harvest sprouting; however, extended dormancy can interfere with malt production and uniform germination upon sowing. In this study, we used Cas9‐induced targeted mutagenesis to create single and double mutants in QTL FOR SEED DORMANCY 1 (Qsd1) and Qsd2 in the same genetic background. We performed germination assays in independent qsd1 and qsd2 single mutants, as well as in two double mutants, which revealed a strong repression of germination in the mutants. These results demonstrated that normal early grain germination requires both Qsd1 and Qsd2 function. However, germination of qsd1 was promoted by treatment with 3% hydrogen peroxide, supporting the notion that the mutants exhibit delayed germination. Likewise, exposure to cold temperatures largely alleviated the block of germination in the single and double mutants. Notably, qsd1 mutants partially suppress the long dormancy phenotype of qsd2, while qsd2 mutant grains failed to germinate in the light, but not in the dark. Consistent with the delay in germination, abscisic acid accumulated in all mutants relative to the wild type, but abscisic acid levels cannot maintain long‐term dormancy and only delay germination. Elucidation of mutant allele interactions, such as those shown in this study, are important for fine‐tuning traits that will lead to the design of grain dormancy through combinations of mutant alleles. Thus, these mutants will provide the necessary germplasm to study grain dormancy and germination in barley.

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“…Several other MTAs were identified with GWA analysis on the logistic parameters. Surprisingly, the SD1 region was not identified with either the centering or the rate parameter with the full logistic model, despite its consistent qualitative, if not quantitative, association with changing the rate of dormancy loss (Sato et al., 2016; Sweeney, Rooney, Walling, & Sorrells, 2021; Vetch et al., 2020).…”

Section: Discussionmentioning

confidence: 99%

“…(2016), a SNP in the untranslated translated region of HvGA20ox1 on chromosome 5H, and the SNP identified to be the causative mutation in HvMKK3 responsible for loss of primary dormancy by Vetch et al. (2020) within North American germplasm. See Sweeney, Rooney, Walling, and Sorrells (2021) for a detailed description of these markers.…”

Section: Methodsmentioning

confidence: 99%

“…The causative gene at SD1 was an alanine aminotransferase ( HvAlaAT1 , HORVU.MOREX.r2.5HG0398940) (Sato et al., 2016) and at SD2 , a mitogen activated protein kinase kinase ( HvMKK3 , HORVU.MOREX.r2.5HG0447180) (Nakamura et al., 2016). Both affect primary dormancy levels, while the HvAlaAT1 has been shown to affect dormancy duration as well (Vetch et al., 2020). Sweeney, Rooney, Walling, and Sorrells (2021) showed that multiple alleles of HvMKK3 exist in the population used for this study and more broadly within Western U.S. and Canadian germplasm, and that these alleles are associated with differences in germination traits and malting quality.…”

Section: Introductionmentioning

confidence: 99%

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Time series barley germination is predictable and associated with known seed dormancy loci

2021

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Preharvest sprouting (PHS) resistance is essential in malting barley (Hordeum vulgare L.) production to prevent damage caused by late season moisture but may be negatively correlated with malting quality traits. The germination percentage and germination rate (GI) in malting barley are measures of both PHS resistance and suitability for malting. Functional principal component analysis (FPCA) and logistic regression on time series spring malting barley GE and GI were performed to identify genetic regions associated with germination trait changes from 0 to 22 wk after maturity. Both analysis methods identified the SD1 and SD2 regions known to affect germination traits, as well as one novel locus on chromosome 6H at 473 Mbp. Several other associations were detected with a single analysis method. Genomic prediction (GP) was used in conjunction with the time series models to test GE and GI predictability over time. Germination traits of unobserved lines at unobserved times were predicted with high accuracy using ridge regression GP coupled with FPCA or logistic regression. The results demonstrate applicability of time series data analysis in determining genetics of germination trait changes in malting barley and that time series germination is predictable. Threshold traits calculated with these time series models, such as the after‐ripening time needed until a line achieves a GE of 95%, can be used as an estimate for dormancy duration, which will be useful in breeding for combined PHS resistance and malting quality.

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Mutations in the HvMKK3 and HvAlaAT1 genes affect barley preharvest sprouting and after‐ripened seed dormancy

Cited by 10 publications

References 33 publications

Interactions of the barley SD1 and SD2 seed dormancy loci influence preharvest sprouting, seed dormancy, and malting quality

Interactions of the barley SD1 and SD2 seed dormancy loci influence preharvest sprouting, seed dormancy, and malting quality

Regulation of germination by targeted mutagenesis of grain dormancy genes in barley

Time series barley germination is predictable and associated with known seed dormancy loci

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