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Journal Articles International journal of advanced research Year : 2022

Expression complementation of gene presence/absence polymorphisms in hybrids contributes importantly to heterosis in sunflower

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Abstract

ntroduction: Numerous crops have transitioned to hybrid seed production to increase yields and yield stability through heterosis. However, the molecular mechanisms underlying heterosis and its stability across environments are not yet fully understood. Objectives: This study aimed to (1) elucidate the genetic and molecular mechanisms underlying heterosis in sunflower, and (2) determine how heterosis is maintained under different environments.Methods: Genome-wide association (GWA) analyses were employed to assess the effects of presence/ab-sence variants (PAVs) and stop codons on 16 traits phenotyped in the sunflower association mapping population at three locations. To link the GWA results to transcriptomic variation, we sequenced the tran-scriptomes of two sunflower cultivars and their F1 hybrid (INEDI) under both control and drought condi-tions and analyzed patterns of gene expression and alternative splicing.Results: Thousands of PAVs were found to affect phenotypic variation using a relaxed significance thresh-old, and at most such loci the "absence" allele reduced values of heterotic traits, but not those of non-heterotic traits. This pattern was strengthened for PAVs that showed expression complementation in INEDI. Stop codons were much rarer than PAVs and less likely to reduce heterotic trait values. Hybrid expression patterns were enriched for the GO category, sensitivity to stimulus, but all genotypes responded to drought similarily - by up-regulating water stress response pathways and down -regulating metabolic pathways. Changes in alternative splicing were strongly negatively correlated with expression variation, implying that alternative splicing in this system largely acts to reinforce expression responses.Conclusion: Our results imply that complementation of expression of PAVs in hybrids is a major contrib-utor to heterosis in sunflower, consistent with the dominance model of heterosis. This mechanism can account for yield stability across different environments. Moreover, given the much larger numbers of PAVs in plant vs. animal genomes, it also offers an explanation for the stronger heterotic responses seen in the former.
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hal-03953577 , version 1 (24-01-2023)

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Attribution - CC BY 4.0

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Joon Seon Lee, Mojtaba Jahani, Kaichi Huang, Jennifer Mandel, Laura Marek, et al.. Expression complementation of gene presence/absence polymorphisms in hybrids contributes importantly to heterosis in sunflower. International journal of advanced research, 2022, 42, pp.83-98. ⟨10.1016/j.jare.2022.04.008⟩. ⟨hal-03953577⟩
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