Background Classical genetic concepts to explain heterosis attribute the superiority of F1-hybrids over their homozygous parents to the complementation of unfavorable by beneficial alleles (dominance) or to heterozygote advantage (overdominance). Here we analyze 112 intermated B73xMo17 recombinant inbred lines of maize and their backcrosses to their original parents B73 and Mo17 to obtain hybrids with an average heterozygosity of ~ 50%. This genetic architecture allows studying the influence of homozygous and heterozygous genomic regions on gene expression in hybrids. Results We demonstrate that single parent expression (SPE) complementation explains between − 8% and 29% of the mid-parent heterotic variance in these hybrids. In this expression pattern, consistent with dominance, genes are active in only one parent and in the hybrid, thus increasing the number of expressed genes in hybrids. Furthermore, we establish that eQTL regulating SPE genes are predominantly located in heterozygous regions of the genome. Finally, we identify an SPE gene that regulates lateral root density in hybrids. Remarkably, the activity of this gene depends on the presence of a Mo17 allele in an eQTL that regulates this gene. Conclusions Here we show that dominance of SPE genes influences the number of active genes in hybrids, while heterozygosity is instrumental for the regulation of these genes. This finding supports the notion that the genetic constitution of distant regulatory elements is instrumental for the activity of heterosis-associated genes. In summary, our results connect genetic variation at regulatory loci and the degree of heterozygosity with phenotypic variation of heterosis via SPE complementation.

Arabidopsis remains one of the best studied models today and has a number of remarkable chemical defense systems which actively engage, interact and preven

Iron acquisition is a critical challenge for plants, especially in iron-deficient soils. Recent research underscores the importance of root-exuded coumarins in modulating the root microbiome communi.....

Abstract. Purine-based metabolites serve as essential mediators of signaling, immunity, and host-microbe interactions across biological kingdoms. This revi

PhD candidate at Max Planck Institute for Plant Breeding Research in Parker group studying 🍄🌱⌬ @parkergroup.bsky.social @mpipz.bsky.social

In this study, Kraska et al. identify MYB68 as a novel regulator of endodermal suberization, linked to the formation of distinct identities in the xylem-pole-associated endodermis. The research uncove...

Iron acquisition is a critical challenge for plants, especially in iron-deficient soils. Recent research underscores the importance of root-exuded coumarins in modulating the root microbiome community...