Genetic architecture and functional consequences of lateral root length in maize

Area of Science:

• Plant Genetics
• Agricultural Science
• Crop Breeding

Background:

• Understanding root architecture is key for sustainable agriculture and resource-efficient crop varieties.
• Maize (Zea mays) landraces offer valuable genetic diversity for trait dissection.

Purpose of the Study:

• To dissect the genetic basis of lateral root (LR) length in maize across different developmental stages.
• To identify quantitative trait loci (QTL) and candidate genes for LR length.
• To investigate the impact of nutrient and water availability on LR length and biomass.

Main Methods:

• Phenotypic analysis of LR length in an Austrian maize landrace.
• Quantitative trait loci (QTL) mapping at vegetative (V6) and reproductive (R2, R6) stages.
• Fine-mapping of significant QTL and candidate gene identification using genomics.
• Environmental treatment experiments (nitrogen, phosphorus, irrigation).

Main Results:

• High heritability of LR length was observed.
• Eight QTL for LR length were detected at R2, four overlapping at R6; no overlap with V6 QTL, suggesting stage-specific regulation.
• The major QTL, qlr1, was fine-mapped to a 2.3 Mb region containing 46 genes.
• LR length positively correlated with biomass under optimal nutrients but not under nitrogen stress.

Conclusions:

• Genetic regulation of maize LR length differs between vegetative and reproductive stages.
• Identified QTL and candidate genes provide targets for breeding resource-efficient maize varieties.
• LR length is an important trait for maize adaptation to varying environmental conditions, particularly nutrient availability.