Single-parent expression complementation contributes to phenotypic heterosis in maize hybrids

Area of Science:

• Plant genetics
• Molecular biology
• Agricultural science

Background:

• Heterosis, or hybrid vigor, explains the superior performance of F1-hybrids.
• The dominance model posits heterosis arises from complementing deleterious alleles with beneficial ones.
• Single-parent expression (SPE) complementation occurs when genes are active in one parent but not the other.

Purpose of the Study:

• To investigate the role of SPE complementation in maize hybrid performance.
• To correlate the number of SPE genes with mid-parent heterosis (MPH).
• To analyze the functional enrichment of maternally and paternally active SPE genes.

Main Methods:

• Analyzing gene expression in genetically diverse maize hybrids.
• Quantifying SPE genes across different tissues.
• Correlating SPE gene counts and module enrichment with phenotypic traits.
• Performing gene ontology term enrichment analyses.

Main Results:

• Approximately 700 additional genes were active on average in maize hybrids due to SPE complementation.
• The number of SPE genes significantly associated with MPH across all surveyed traits.
• Maternally active SPE genes (SPE_B) correlated positively with traits and were linked to growth/development.
• Paternally active SPE genes (SPE_X) correlated negatively with traits and were linked to defense/stress response.

Conclusions:

• Phenotypic heterosis in maize is linked to the extent of SPE gene expression complementation.
• SPE complementation contributes to hybrid vigor by coordinating development and stress responses in fluctuating environments.
• SPE_B and SPE_X gene expression patterns have distinct roles in hybrid performance.