Stomatal Responses to Rising Temperatures UPSC NOTE

  Stomata are tiny pores on leaf surfaces that regulate gas exchange, controlling water loss through transpiration and carbon dioxide inta...

 

• Stomata are tiny pores on leaf surfaces that regulate gas exchange, controlling water loss through transpiration and carbon dioxide intake for photosynthesis.

• Stomatal openings play a crucial role in minimizing heat damage to plants.

Key Findings from the Study

• The study identified two distinct mechanisms used by plants to respond to elevated temperatures: a primary pathway linked to carbon dioxide sensing and a secondary pathway activated under extreme heat.

• Carbon Dioxide Sensing: Carbon dioxide sensors play a central role in the primary heat response pathway.

• When leaves experience rapid warming, carbon dioxide sensors detect the decrease in carbon dioxide levels due to increased photosynthesis. 

• This triggers stomatal opening to facilitate more carbon dioxide intake.

• Secondary Heat Response: Under extreme heat conditions, when photosynthesis is stressed, the stomata bypass the carbon dioxide sensing system and activate a secondary heat response pathway. 

• This pathway functions as a cooling mechanism, similar to sweating.

Challenges and Innovations

• Measurement Difficulties: Scientists faced challenges in measuring stomatal responses to rising temperatures due to the complexity of maintaining constant vapor pressure difference (VPD) while increasing temperature.

• Novel Approach: The researchers developed a novel method to clamp VPD at fixed values while elevating temperatures, allowing for a clearer analysis of stomatal responses.

Vapor pressure difference, or vapor pressure deficit (VPD), is the difference in pressure between the amount of water vapor in the air and the maximum amount of water vapor the air can hold at its current temperature

• The study investigated the genetic mechanisms underlying stomatal temperature responses, including drought hormones, carbon dioxide sensors, and temperature-sensitive proteins.

Conclusion

• The study provides valuable insights into the mechanisms by which plants regulate stomatal openings in response to rising temperatures. 

• The findings highlight the importance of both carbon dioxide sensing and a secondary heat response pathway in mitigating heat stress and maintaining plant function.