Wheat grain protein accumulation and polymerization mechanisms driven by nitrogen fertilization

Area of Science:

• Agricultural Science
• Plant Physiology
• Biochemistry

Background:

• Wheat grain yield and protein content are negatively correlated, posing a challenge for simultaneous improvement.
• Nitrogen fertilization is a key factor influencing wheat quality and yield.
• Understanding nitrogen-use efficiency is crucial for optimizing wheat production.

Purpose of the Study:

• To investigate nitrogen-use efficiency traits in Australian bread wheat varieties.
• To elucidate the mechanisms behind simultaneous increases in grain yield and protein content.
• To identify key proteins involved in nitrogen-mediated protein accumulation.

Main Methods:

• Multi-site field trials over three years with varying nitrogen treatments.
• High-performance liquid chromatography (HPLC) for storage protein composition analysis.
• Proteomics, yeast two-hybrid experiments, and enzyme activity assays.

Main Results:

• Grain yield and protein content responded similarly to nitrogen availability, with genotype being a critical factor.
• High nitrogen promoted glutamine synthetase activity and gluten macropolymer accumulation.
• Peptidyl-prolyl cis-trans isomerase (PPIase) SUMOylation, facilitated by small ubiquitin-related modifier 1, and luminal-binding protein 2 were identified as key in protein polymerization.

Conclusions:

• Nitrogen fertilization strategies can be optimized to enhance both wheat yield and protein content.
• Specific molecular mechanisms involving PPIase and luminal-binding protein 2 are crucial for protein accumulation under high nitrogen.
• Genotypic variation plays a significant role in nitrogen response and protein yield.