The wheat ABA hypersensitive ERA8 mutant is associated with increased preharvest sprouting tolerance and altered hormone accumulation
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Wheat preharvest sprouting (PHS) is the germination of mature grain on the mother plant when rain occurs before harvest. Higher abscisic acid (ABA) hormone levels and sensitivity are associated with higher seed dormancy and PHS tolerance. Consistent with this, the ABA hypersensitive ENHANCED RESPONSE TO ABA8 (ERA8) mutant resulted in increased dormancy and PHS tolerance in soft white spring wheat ‘Zak’. ERA8 seeds were initially less responsive to germination-rescue by the hormone gibberellin (GA). ERA8 gained GA and lost ABA sensitivity more slowly than wild-type during dormancy loss through after-ripening and cold imbibition. This study examined if increased ABA sensitivity in ERA8 likely resulted from increased ABA signaling or increased ABA hormone levels. Zak ERA8 had higher initial grain dormancy although endogenous embryo ABA levels were similar in Zak ERA8 and wild-type, suggesting that increased dormancy was due to increased ABA signaling rather than increased ABA accumulation. ABA levels declined with Zak ERA8 after-ripening, suggesting that ABA turnover is not defective. Elevated ERA8 dormancy was also associated with increased embryonic jasmonic acid-Ile and aleurone indole-3-acetic acid (IAA) levels. The possible implication that other plant hormones may influence wheat seed dormancy and germination are discussed.
KeywordsAbscisic acid Gibberellin Auxin Wheat Preharvest sprouting Seed dormancy
The authors sincerely thank Dr. Mark E. Sorrells for performing spike-wetting tests in 2008 and 2010. Thanks are due to Rehana S. Parveen and Dustan Cwick for expert assistance. Thanks are also due to the USDA-ARS field crew for planting and harvesting. A special thanks to the Garland-Campbell and Steber labs for helpful feedback on the research and manuscript.
This work was funded by the National Science Foundation’s East Asia and Pacific Summer Institute Award grant 1209878 (to K.M.T.), the Japanese Society for the Promotion of Science Summer Internship Award (to K.M.T. and M.S.), the Washington Grain Alliance (to C.M.S.), and the USDA-ARS (to C.M.S. and K.G.C.).
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Ali-Rachedi S, Bouinot D, Wagner M-H et al (2004) Changes in endogenous abscisic acid levels during dormancy release and maintenance of mature seeds: studies with the Cape Verde Islands ecotype, the dormant model of Arabidopsis thaliana. Planta 219:479–488. doi: 10.1007/s00425-004-1251-4 CrossRefPubMedGoogle Scholar
- Johnson RR, Wagner RL, Verhey SD, Walker-Simmons MK (2002) The Abscisic acid-responsive kinase PKABA1 interacts with a seed-specific abscisic acid response element-binding factor, TaABF, and phosphorylates TaABF peptide sequences. Plant Physiol 130:837–846. doi: 10.1104/pp.001354 CrossRefPubMedPubMedCentralGoogle Scholar
- Kashiwakura Y, Kobayashi D, Jikumaru Y, et al (2016) Highly sprouting tolerant wheat grain exhibits extreme dormancy and cold imbibition resistant accumulation of abscisic acid. Plant Cell Physiol pcw051. doi: 10.1093/pcp/pcw051
- Kidwell KK, Shelton GB, DeMacon VL et al (2012) Registration of ‘Babe’ wheat. J Plant Regist 6:156–160Google Scholar
- McMaster GJ, Derera NF (1976) Methodology and sample preparation when screening for sprouting damage in cereals. Cereal Res Commun 4:251–254Google Scholar
- Nakashima K, Fujita Y, Kanamori N et al (2009) Three Arabidopsis SnRK2 protein kinases, SRK2D/SnRK2.2, SRK2E/SnRK2.6/OST1 and SRK2I/SnRK2.3, involved in ABA signaling are essential for the control of seed development and dormancy. Plant Cell Physiol 50:1345–1363. doi: 10.1093/pcp/pcp083 CrossRefPubMedGoogle Scholar
- Schramm EC, Abellera JC, Strader LC et al (2010) Isolation of ABA-responsive mutants in allohexaploid bread wheat (Triticum aestivum L.): drawing connections to grain dormancy, preharvest sprouting, and drought tolerance. Plant Sci 179:620–629. doi: 10.1016/j.plantsci.2010.06.004 CrossRefGoogle Scholar
- Warner RL, Kudrna DA, Spaeth SC, Jones SS (2000) Dormancy in white-grain mutants of Chinese Spring wheat (Triticum aestivum L.). Seed Sci Res 10:51–60Google Scholar
- Xu Q, Truong TT, Barrero JM, et al (2016) A role for jasmonates in the release of dormancy by cold stratification in wheat. J Exp Bot erw172. doi: 10.1093/jxb/erw172
- Yoshimoto K, Jikumaru Y, Kamiya Y et al (2009) Autophagy negatively regulates cell death by controlling NPR1-dependent salicylic acid signaling during senescence and the innate immune response in Arabidopsis. Plant Cell 21:2914–2927. doi: 10.1105/tpc.109.068635 CrossRefPubMedPubMedCentralGoogle Scholar