Genetic variation at bx1 controls DIMBOA content in maize

Area of Science:

• Plant genetics
• Maize breeding
• Biochemistry

Background:

• 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) is crucial for maize (Zea mays L.) resistance to corn borers.
• Genes for DIMBOA synthesis are on chromosome 4, a region linked to insect resistance QTLs.
• Previous QTL mapping lacked resolution to confirm bx loci's role in resistance variability.

Purpose of the Study:

• Identify QTLs for DIMBOA synthesis in diverse maize inbreds.
• Assess QTL stability for DIMBOA content across different years.
• Investigate the role of the bx1 gene in DIMBOA variation using association mapping.

Main Methods:

• Utilized eight RIL families from a nested association mapping population.
• Evaluated two RIL families over 2 years to check QTL stability.
• Performed association mapping with 281 diverse inbred lines, focusing on the bx1 gene.

Main Results:

• Identified stable QTLs for DIMBOA content across environments.
• A model with eight markers explained 34% of phenotypic variability in DIMBOA.
• Largest QTL co-localized with DIMBOA pathway genes; bx1 polymorphisms significantly affected DIMBOA content.

Conclusions:

• QTLs for DIMBOA synthesis are stable and linked to the DIMBOA pathway gene cluster.
• Sequence variations in bx1 influence DIMBOA levels in maize.
• The precise causal polymorphisms for the chromosome 4.01 QTL were not identified, possibly due to sequencing limitations, linkage disequilibrium, or multiple causal variants.