A worldwide maize panel revealed new genetic variation for cold tolerance

Area of Science:

• Plant genetics and breeding
• Agricultural science
• Crop improvement

Background:

• Maize (Zea mays L.) exhibits limited cold tolerance, hindering its production potential in temperate climates.
• Developing cold-tolerant maize varieties is essential for expanding cultivation and yield in cooler regions.
• Genetic improvement for cold tolerance is a significant challenge in maize breeding programs.

Purpose of the Study:

• To identify genetic loci and candidate genes associated with cold tolerance in maize at germination and seedling stages.
• To assess the genetic diversity for cold tolerance within a large panel of maize inbred lines.
• To provide insights for developing more effective breeding strategies for cold-tolerant maize.

Main Methods:

• Evaluation of a diverse association panel comprising 836 maize inbred lines.
• Genotyping using single-nucleotide polymorphisms (SNPs) to detect quantitative trait loci (QTL).
• Analysis of traits related to emergence and early growth under cold stress conditions.

Main Results:

• A broader genetic diversity for cold tolerance was observed than previously reported, with moderately high heritability.
• 187 significant SNPs were identified, forming 159 QTL for emergence and early growth traits.
• Most identified QTL had small effects and were environment-specific, with favorable alleles found in specific inbred lines.

Conclusions:

• The study identified substantial and potentially novel genetic variability for maize cold tolerance.
• Genomic selection is proposed as the most promising approach for breeding cold-tolerant maize due to the prevalence of small-effect QTL.
• Further exploration of diverse germplasm may uncover additional favorable alleles, but large-effect alleles for cold tolerance are unlikely to be discovered.