Dynamic patterns of the translatome in a hybrid triplet show translational fractionation of the maize subgenomes

Heterosis, the phenomenon in which hybrids outperform their parents, has been utilized in maize (Zea mays L.) for over 100 years. To provide a more complete understanding of heterosis, we collected a comprehensive transcriptome and translatome dataset on seedling leaves for B73, Mo17, and their F-1 hybrid, which provided a dynamic landscape of transcriptomic and translatomic variation in maize. Although additivity accounted for a large proportion of variation at two omits-levels, an elevated nonadditive effect was observed in the translatome, especially in the translated subgenome maize1 genes, and the genes that switched from additivity in the transcriptome to nonadditivity in the translatome were significantly enriched in the subgenome maize1. Many genes with allele-specific expression and translation show dramatic regulatory switches between the transcriptome and translatome, and partial genes with allele-specific translation underlying regulatory mechanism also exhibited subgenome bias. Interestingly, we found the translated isoforms show different expression patterns compared with transcriptome and more genes changed their dominant isoforms during the genetic flow from parents to the hybrid at the translatome level. The translated genes with switched dominant isoforms significantly biased to the subgenome maize2 while genes with conserved dominant isoforms significantly enriched in subgenome maizel. Together, the dynamic changed patterns in translatome across hybrid and parental lines show translational fractionation of the maize subgenomes, which may be associated with heterosis in maize and provides a potential theoretical basis for breeding. (C) 2021 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.