Abstract
Key message
The early flowering of Lalu was determined to be due to a novel spontaneous eam8 mutation, which resulted in intron retention and the formation of a putative truncated protein.
Abstract
Barley is a staple crop grown over an extensive area in the Qinghai-Tibetan Plateau. Understanding the genetic mechanism for its success in a high altitude is important for crop improvement in marginal environments. Early flowering is a critical adaptive trait that strongly influences reproductive fitness in a short growing season. Loss-of-function mutations at the circadian clock gene EARLY MATURITY 8 (EAM8) promote rapid flowering. In this study, we identified a novel, spontaneous recessive eam8 mutant with an early flowering phenotype in a Tibetan barley landrace Lalu, which is natively grown at a high altitude of approximately 4000 m asl. The co-segregation analysis in a F2 population derived from the cross Lalu (early flowering) × Diqing 1 (late flowering) confirmed that early flowering of Lalu was determined to be due to an allele at EAM8. The eam8 allele from Lalu carries an A/G alternative splicing mutation at position 3257 in intron 3, designated eam8.l; this alternative splicing event leads to intron retention and a putative truncated protein. Of the 134 sequenced barley accessions, which are primarily native to the Qinghai-Tibet Plateau, three accessions carried this mutation. The eam8.l mutation was likely to have originated in wild barley due to the presence of the Lalu haplotype in H. spontaneum from Tibet. Overall, alternative splicing has contributed to the evolution of the barley circadian clock and in the short-season adaptation of local barley germplasm. The study has also identified a novel donor of early-flowering barley which will be useful for barley improvement.
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Acknowledgements
We thank Prof. Xiaogang Ma (Qinghai Academy of Agriculture and Forestry Sciences), Meijin Liu (Gannan Tibetan Autonomous Prefecture Institute of Agricultural Sciences) and Kaijin Yang (Ganzi Tibetan Autonomous Prefecture Institute of Agricultural Sciences) for generously providing the barley germplasm. This research was financially supported by the National Key Research and Development Program (2016YFD0102000), the Chinese Academy of Sciences Associate Scholar Program for the West Light Foundation, the Key research and development and transformation project of Qinghai Province (2016-NK-131), the Qinghai Province Natural Science Foundation (2015-ZJ-915Q) and the Qinghai Province Applied Basic Research Project (2015-ZJ-702).
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Communicated by Takao Komatsuda.
T. Xia and L. Zhang have contributed equally.
The seed stock of Lalu is available upon request to Yuhu Shen, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, at shenyuhu@nwipb.cas.cn.
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122_2016_2848_MOESM1_ESM.pdf
Fig. S1 Alignment of cDNA sequences from Lalu, Diqing and cv. Bonus (JN180296). Variants inducing amino acid substitutions are shown in bold. Following Zakhrabekova et al. (2012), matching residues are indicated by asterisks, conserved substitutions by colons and semi-conserved substitutions by dots. (PDF 63 KB)
122_2016_2848_MOESM2_ESM.tif
Fig. S2 RT-PCR products used for the detection of intron retention in intron 3 of EAM8. 1: Molecular weight marker, L1: Leduheiqingke, 8: accession 86072, 81: accession 86587, I: RT-PCR products amplified with the primer pair α-Tubulin-F/-R, II: RT-PCR products amplified with the primer pair EAM8-1128-F/EAM8-4138-R. (TIF 329 KB)
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Xia, T., Zhang, L., Xu, J. et al. The alternative splicing of EAM8 contributes to early flowering and short-season adaptation in a landrace barley from the Qinghai-Tibetan Plateau. Theor Appl Genet 130, 757–766 (2017). https://doi.org/10.1007/s00122-016-2848-2
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DOI: https://doi.org/10.1007/s00122-016-2848-2