Rising rates of starch degradation during daytime and trehalose 6-phosphate optimize carbon availability

Area of Science:

• Plant Physiology
• Biochemistry
• Metabolic Regulation

Background:

• Plants store starch during the day and break it down at night for energy.
• Starch synthesis and degradation are typically considered separate processes occurring at different times.
• Recent findings indicate starch degradation also occurs during daylight hours.

Purpose of the Study:

• To investigate the regulation and function of starch degradation during the light period in plants.
• To determine if light-induced starch degradation is influenced by time of day or sugar availability.
• To explore the role of simultaneous starch synthesis and degradation in optimizing plant growth.

Main Methods:

• Mathematical modeling to simulate starch degradation rates.
• Experimental approaches to analyze plant responses.
• Measurement of protein and cell wall synthesis rates under simulated conditions.

Main Results:

• Starch degradation in the light is primarily regulated by the time until dawn, not dusk.
• Trehalose 6-phosphate, a sucrose availability signal, inhibits light-induced starch degradation.
• A mathematical model accurately simulates observed degradation patterns, including feedback inhibition by trehalose 6-phosphate.
• Simultaneous starch synthesis and degradation buffer growth during twilight, maintaining high synthesis rates.

Conclusions:

• Starch degradation in the light shares regulatory mechanisms with nocturnal degradation.
• Light-induced starch degradation is crucial for stabilizing carbon availability and signaling.
• This process optimizes plant growth under natural light cycles by preventing over-accumulation and ensuring consistent resource supply.