Post-Heading High Nighttime Temperature Impairs Grain Protein-Starch Balance and Rice Quality Through Altering...

Area of Science:

• Agricultural Science
• Plant Physiology
• Genetics

Background:

• High nighttime temperatures (HNT) impair rice quality by disrupting nutrient transport and grain filling.
• The primary drivers (source vs. sink limitation) and genotypic variations in rice response to HNT remain unclear.
• Understanding the physiological basis of HNT effects on grain protein and quality is crucial.

Purpose of the Study:

• To investigate if nitrogen remobilization from leaves to grains under HNT influences genotypic differences in rice grain quality.
• To explore the physiological mechanisms behind genotypic variation in grain protein content under HNT.
• To assess the impact of HNT on rice eating and cooking quality.

Main Methods:

• Two rice cultivars (HHZ and YY4949) were subjected to control (30/22°C day/night) and HNT (30/27°C day/night) conditions over two years.
• Evaluated genotypic variations in grain storage substances, protein content, and the glutelin/prolamin ratio.
• Analyzed nitrogen remobilization, chloroplast degradation, and expression of nitrogen metabolism-related genes and transporters.

Main Results:

• Significant genotypic variation in response to HNT was observed.
• YY4949 showed increased grain protein and altered protein composition under HNT, negatively affecting eating and cooking quality.
• HNT accelerated nitrogen remobilization in YY4949, exacerbating source limitation and disrupting starch-protein balance.

Conclusions:

• Nitrogen remobilization from leaves to grains is a key factor in genotypic differences in rice quality under HNT.
• Genetic control of nitrogen remobilization offers a strategy for breeding climate-resilient rice with improved grain quality.
• Targeting nitrogen remobilization can help mitigate the negative impacts of HNT on rice production.