Genomic and evolutionary evidence for drought adaptation of grass allopolyploid Brachypodium hybridum
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(Published version)
Date
2025
Authors
Wang, Y.
Chen, G.
Zeng, F.
Deng, F.
Yang, Z.
Han, Z.
Xu, S.
Nevo, E.
Catalán, P.
Chen, Z.-H.
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Zhang, J.
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Journal of Experimental Botany, 2025; 76(10):2924-2938
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Yuanyuan Wang, Guang Chen, Fanrong Zeng, Fenglin Deng, Zujun Yang, Zhigang Han, Shengchun Xu, Eviatar Nevo, Pilar Catalán, and Zhong-Hua Chen
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Abstract
Climate change is increasing the frequency and severity of drought worldwide, threatening the environmental resilience of cultivated grasses. However, the genetic diversity in many wild grasses could contribute to the development of climate-adapted varieties. Here, we elucidated the impact of polyploidy on drought responses using allotetraploid Brachypodium hybridum (B. hybridum) and its progenitor diploid species Brachypodium stacei (B. stacei). Our findings suggest that progenitor species’ genomic legacies resulting from hybridization and whole-genome duplications conferred greater ecological adaptive advantages to B. hybridum compared with B. stacei. Genes related to stomatal regulation and the immune response from S-subgenomes were under positive selection during speciation, underscoring their evolutionary importance in adapting to environmental stresses. Biased expression in polyploid subgenomes (B. stacei-type and B. distachyon-type) significantly influenced differential gene expression, with the dominant subgenome exhibiting more differential expression. B. hybridum adapted a drought escape strategy characterized by higher photosynthetic capacity and lower intrinsic water-use efficiency than B. stacei, driven by a highly correlated coexpression network involving genes in the circadian rhythm pathway. In summary, our study shows the influence of polyploidy on ecological and environmental adaptation and resilience in model Brachypodium grasses. These insights hold promise for informing the breeding of climate-resilient cereal crops and pasture grasses.
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© The Author(s) 2025. Published by Oxford University Press on behalf of the Society for Experimental Biology. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs licence (https://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reproduction and distribution of the work, in any medium, provided the original work is not altered or transformed in any way, and that the work is properly cited. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com