Genetic Dissection and Functional Validation of DXS2 Controlling Antheraxanthin Content in Maize Kernels

Area of Science:

• Plant Genetics
• Biochemistry
• Agricultural Science

Background:

• Antheraxanthin (ANT) is a vital xanthophyll carotenoid in maize kernels, but its genetic underpinnings are not well understood.
• Understanding ANT's genetic basis is crucial for improving maize nutritional value through breeding.

Purpose of the Study:

• To investigate the genetic architecture of ANT content in maize kernels.
• To identify quantitative trait loci (QTLs) and causal genes controlling ANT accumulation.
• To explore the role of DXS2 in ANT biosynthesis and its connection to the MEP pathway.

Main Methods:

• Utilized a teosinte-maize BC2F5 population for genetic analysis across multiple environments.
• Performed QTL mapping, fine mapping, and candidate gene analysis.
• Conducted functional validation using MuDR insertion mutants and transcriptomic analysis.

Main Results:

• ANT content in maize kernels exhibited significant phenotypic variation and high heritability.
• Eleven QTLs for ANT content were identified, with a major-effect locus (L4) on chromosome 7.
• DXS2, encoding 1-deoxy-D-xylulose 5-phosphate synthase 2, was identified as the causal gene for L4, significantly impacting ANT accumulation.
• DXS2 plays a critical role in the MEP pathway, carotenoid biosynthesis, and downstream metabolic networks.

Conclusions:

• The genetic architecture of ANT accumulation in maize kernels has been elucidated.
• DXS2 is a key regulator linking the MEP pathway to carotenoid and ANT metabolism.
• These findings provide valuable genetic resources and theoretical support for carotenoid biofortification in maize breeding.