Regulation of heterosis-associated gene expression complementation in maize hybrids

Area of Science:

• Plant genetics
• Maize breeding
• Molecular biology

Background:

• Classical genetics explains heterosis via dominance or overdominance.
• Maize hybrids exhibit F1 superiority over homozygous parents.
• Investigating gene expression in hybrids with controlled heterozygosity is key.

Purpose of the Study:

• To analyze the influence of homozygous and heterozygous regions on gene expression in maize hybrids.
• To understand the role of single parent expression (SPE) complementation in heterosis.
• To identify regulatory elements controlling SPE genes and their impact on heterosis.

Main Methods:

• Analysis of 112 intermated B73xMo17 recombinant inbred lines and their backcrosses in maize.
• Quantification of single parent expression (SPE) complementation's contribution to heterotic variance.
• Identification of expression quantitative trait loci (eQTL) for SPE genes.
• Characterization of an SPE gene regulating lateral root density.

Main Results:

• SPE complementation explains 8-29% of mid-parent heterotic variance.
• SPE genes are predominantly regulated by eQTL located in heterozygous genomic regions.
• An SPE gene influencing lateral root density was identified, dependent on a specific parental allele.

Conclusions:

• Dominance of SPE genes impacts the number of active genes in hybrids.
• Heterozygosity is crucial for the regulation of SPE genes, influencing heterosis.
• Genetic variation at regulatory loci and heterozygosity are linked to heterosis through SPE complementation.