Revisiting the hetero-fertilization phenomenon in maize

Area of Science:

• Plant Genetics
• Reproductive Biology
• Molecular Breeding

Background:

• Marker-assisted selection (MAS) traditionally relies on morphological markers, limiting its application to specific populations.
• Aberrant reproductive phenomena, like hetero-fertilization (HF), can complicate genetic analysis and breeding efforts.
• Seed DNA-based genotyping offers a novel approach to study these phenomena across diverse genotypes.

Purpose of the Study:

• To develop and validate a seed DNA-based genotyping system for understanding hetero-fertilization (HF) in monocot species.
• To quantify HF frequencies in various F(2) and three-way cross populations.
• To assess the impact of HF on the accuracy of marker-assisted selection (MAS).

Main Methods:

• Implementation of a large-scale experiment using seven F(2) and four three-way cross populations (534-1024 individuals each).
• Analysis of endosperm and leaf DNA genotypes to detect mismatches indicative of HF.
• Confirmation of identified HF events using 1032 single nucleotide polymorphic (SNP) markers.

Main Results:

• HF frequencies ranged from 0.14% to 3.12%, with an average of 1.46%, primarily contributed by pollen gametes.
• Three-way crosses enabled the first detection of maternal gamete contribution to HF (0.14%-0.65%).
• A single polymorphic marker detects only 50% of HF events; combining seven markers detects 99%.

Conclusions:

• Seed DNA-based genotyping is effective for detecting HF and understanding its frequency in diverse germplasm.
• The relatively low HF frequencies observed suggest a limited impact on the accuracy of MAS.
• Comparative DNA analysis can elucidate relationships between HF, haploidy, and apomixis.