Genetic Variation, DIMBOA Accumulation, and Candidate Gene Identification in Maize Multiple Insect-Resistance

Area of Science:

• Plant Genetics
• Agricultural Science
• Entomology

Background:

• Maize seedlings produce 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA), a compound crucial for insect resistance against pests like the Asian corn borer and corn leaf aphids.
• While many genetic loci for insect resistance exist, the genetic control of DIMBOA content remains poorly understood.

Purpose of the Study:

• To identify genetic loci and candidate genes controlling DIMBOA content in maize.
• To associate molecular markers with DIMBOA content for marker-trait association analysis.
• To explore the genetic variation and potential for breeding insect-resistant maize varieties.

Main Methods:

• Calculated Best Linear Unbiased Prediction (BLUP) values for DIMBOA content across 310 maize inbred lines in two environments.
• Performed marker-trait association analysis using phenotypic data and BLUP values.
• Integrated newly identified SSR markers with previously reported genetic loci to detect 'hot loci' and candidate genes.

Main Results:

• Identified nine SSRs significantly associated with DIMBOA content, explaining 4.30-20.04% of phenotypic variation.
• Detected 19 'hot loci' with potential pleiotropy, associated with multiple insect-resistant traits.
• Identified 49 candidate genes within hot loci, involved in DIMBOA biosynthesis, sugar metabolism, growth, and enzyme activities.
• Found significant genetic variation for DIMBOA content and SSR markers, with highly and moderately insect-resistant genotypes enriched in the Reid group.

Conclusions:

• The identified SSRs and candidate genes provide valuable targets for understanding and improving DIMBOA-mediated insect resistance in maize.
• The study highlights the complex genetic architecture underlying DIMBOA content and its role in plant defense.
• Selected insect-resistant inbred lines offer promising genetic resources for developing new maize varieties with enhanced pest resistance through breeding programs.