Exploring the phosphorus-starch content balance mechanisms in maize grains using GWAS population and transcriptome...

Area of Science:

• Agricultural Science
• Plant Physiology
• Genetics

Background:

• Understanding the interplay between phosphorus (P) and carbohydrate metabolism is crucial for optimizing crop yield.
• Maize grain quality is influenced by nutrient content and starch accumulation.

Purpose of the Study:

• To investigate the relationship between phosphorus content, starch content, and 100-kernel weight (HKW) in maize.
• To explore the molecular mechanisms underlying the observed correlations, including gene expression and metabolic pathways.

Main Methods:

• Multi-year, multi-plot trials with 307 maize inbred lines.
• Analysis of P content, starch content, and HKW.
• Microscopic examination of starch granules.
• Gene expression analysis (ZmPHOs, AGPase) and pathway enrichment analysis.
• Genome-wide association study (GWAS).

Main Results:

• Significant negative correlation between P content and starch content/HKW; positive correlation between starch content and HKW.
• High-P low-starch (HPLS) grains had smaller, irregular starch granules compared to low-P high-starch (LPHS) grains.
• HPLS lines showed decreased ZmPHOs gene expression and altered enrichment in nucleotide sugar, fatty acid, and ABC transporter pathways.
• GWAS identified 514 associated genes, with Zm00001d052392 linked to P content/HKW.

Conclusions:

• High P content in maize grains is associated with reduced starch accumulation and kernel weight, potentially due to accelerated lipid breakdown and insufficient carbon sources.
• Differential gene expression, particularly in lipid metabolism, plays a role in this phenotype.
• Targeting lipid metabolic pathways presents a novel approach for improving phosphorus-yield balance in maize.