Coordination In Plants

Key Notes:

Definition of Coordination

  • Coordination in plants refers to the regulatory mechanisms that control growth, development, and responses to environmental stimuli.

Types of Coordination

  • Tropic Responses: Directional growth responses toward or away from stimuli (e.g., phototropism toward light, gravitropism toward gravity).
  • Nastic Responses: Non-directional responses to stimuli, such as the opening and closing of flowers or leaves (e.g., thigmonasty in Mimosa pudica when touched).

Hormones in Plant Coordination

  • Auxins: Promote cell elongation and are involved in phototropism and gravitropism.
  • Gibberellins: Stimulate stem elongation, seed germination, and flowering.
  • Cytokinins: Promote cell division and influence shoot and root growth.
  • Abscisic Acid (ABA): Involved in stress responses, such as closing stomata during drought.
  • Ethylene: Regulates fruit ripening and leaf abscission.

Mechanisms of Coordination

  • Signal Transduction Pathways: Hormones trigger responses in target cells through signaling pathways, leading to changes in gene expression and physiological responses.
  • Feedback Mechanisms: Help maintain homeostasis by regulating hormone levels and responses (e.g., when a plant’s water needs are met, ABA levels decrease).

Environmental Factors Influencing Coordination

  • Light: Influences phototropism and the production of chlorophyll; plants can detect light direction and intensity.
  • Gravity: Affects root and shoot orientation; roots grow down (positive gravitropism), while shoots grow up (negative gravitropism).
  • Touch: Can trigger responses in certain plants, such as the folding of leaves in response to touch.

Importance of Coordination in Plants

  • Enables plants to adapt to their environment, maximizing survival and reproductive success.
  • Plays a critical role in processes like flowering, fruiting, and responses to stress.

Examples of Plant Coordination

  • Phototropism: Plants bending toward a light source.
  • Gravitropism: Roots growing downward in response to gravity.
  • Thigmotropism: Climbing plants wrapping around supports when they come into contact.

Let’s practice!