An ARF gene mutation creates flint kernel architecture in dent maize.

Area of Science:

• Plant genetics
• Maize breeding
• Kernel architecture

Background:

• Dent and flint kernel types in maize have distinct physical properties influencing grain use.
• Genetic control of these kernel architectures remains largely unknown, hindering trait introgression.
• Understanding the genetic basis is crucial for combining desirable traits from both dent and flint maize.

Purpose of the Study:

• To identify genes controlling dent and flint kernel architectures in maize.
• To investigate the role of ARFTF17 in kernel phenotype development.
• To explore the potential of ARFTF17 mutations for improving maize kernel quality.

Main Methods:

• Mutation analysis of ARFTF17 in a dent maize genetic background.
• Quantification of Indole-3-acetic acid (IAA) content in the kernel pericarp.
• Gene expression analysis and protein interaction studies (ARFTF17 and MYB40).
• Phenotypic evaluation of kernel texture, integrity, and desiccation.

Main Results:

• ARFTF17 mutation in dent maize reduced pericarp IAA content, inducing a flint-like kernel phenotype.
• ARFTF17 encodes a protein inhibiting MYB40, which regulates PIN1 expression and flavonoid biosynthesis.
• Increased flavonoid biosynthesis potentially diverts metabolic flux from auxin production.
• The ARFTF17 mutation led to reduced cell division and expansion in the pericarp, resulting in denser kernels.
• Introgression of the ARFTF17 mutation improved kernel texture, integrity, and desiccation in dent inbreds and hybrids without yield penalty.

Conclusions:

• ARFTF17 plays a key role in regulating maize kernel architecture through auxin biosynthesis pathways.
• Targeting ARFTF17 offers a novel strategy for enhancing maize kernel quality traits.
• The ARFTF17 mutation provides a valuable tool for breeding improved dent and flint maize varieties.