STOMATA (Syllabus: GS Paper 3 – Sci and Tech)

Context: Scientists from Nagoya University have uncovered a unique mechanism that regulates the opening of stomata in plants. Phosphorylation of the amino acid Thr881 on the plasma membrane proton pump plays a key role in this process.

Stomata

• About: These are minute pores in plant tissue facilitating gas exchange, primarily in leaves but also in some stems.
• Gas Exchange and Photosynthesis: They enable the intake of carbon dioxide crucial for photosynthesis, contributing to plant growth and metabolism.
• Regulation of Water Loss: Stomata aid in reducing water loss by closing during hot or dry conditions, akin to tiny mouths aiding in transpiration.
• Distribution: Typically, stomata are abundant on the underside of leaves, minimizing exposure to heat and air currents, while aquatic plants exhibit a different distribution.
• Specialised cells: A stomata is surrounded by two types of specialized plant cells that differ from other plant epidermal cells.

oThese cells are called guard cells and subsidiary cells.

• Guard cells: They surround stomata, control their opening and closing, responding to internal pressure changes driven by environmental conditions.

oGuard cells contain chloroplasts, essential for photosynthesis, enhancing their capacity to regulate stomatal activity.

• Subsidiary Cells: It provide structural support to guard cells, acting as a protective barrier against excessive expansion and safeguarding neighboring epidermal cells.
• Circadian Rhythm and Stomatal Opening: Stomatal activity follows a circadian rhythm, with a peak opening near noon after a dawn-triggered increase, subsequently declining to mitigate water loss.
• Application of the discovery: The study paves the way for the targeted manipulation of plant physiology, with potential applications in agriculture and environmental sustainability.