Estimating microbial respiratory CO₂ from endophytic bacteria in rice

Area of Science:

• Plant-microbe interactions
• Plant physiology
• Microbial ecology

Background:

• Endophytes are microbes residing within plant tissues, exchanging carbohydrates for symbiotic benefits.
• During respiration, endophytes release CO2 into the plant's intercellular spaces.
• The potential for host plants to re-assimilate this microbial CO2 is largely unexplored.

Purpose of the Study:

• To investigate the re-assimilation of microbial respiratory CO2 by host plants.
• To quantify the contribution of endophyte-derived CO2 to host plant photosynthesis.

Main Methods:

• In planta and in vitro assays were performed.
• Respiration rates of endophyte-symbiotic plants were measured.
• Factors influencing endophyte respiration (microbe load, carbohydrate availability) were assessed.

Main Results:

• Endophyte-inoculated plants exhibited higher in planta respiration rates.
• Endophyte respiration rates were directly dependent on microbial biomass and carbohydrate supply.
• Estimated contribution of microbial CO2 to host photosynthesis reached up to 57% under sufficient carbohydrate conditions.

Conclusions:

• Endophytes significantly contribute to the CO2 pool within host plants through respiration.
• Host plants possess the capacity to re-assimilate this microbial CO2, potentially impacting their carbon balance.
• This microbial CO2 re-assimilation represents a novel aspect of plant-microbe symbiosis and carbon cycling.