Plant Development and Hormone Signalling

Plant Development

• Plant development is characterized by post-embryonic formation of the plant body, with discrete stem cell pools in the shoot and root meristems.
• The shoot apical meristem and lateral meristems form above-ground organs such as stems, leaves, and flowers, while the root apical meristem forms the root system.
• This modular, post-embryonic mode of development allows plants to adapt to environmental stimuli and respond to environmental cues.

Plant Hormones

• Eight principal classes of plant hormones have been characterized: abscisic acid, auxin, brassinosteroids, cytokinins, ethylene, gibberellins, jasmonates, and strigolactones.
• These hormones control plant growth and development, and are also influenced by environmental cues.

Gibberellins

• Gibberellins have a major influence on germination, plant growth, floral development, and flowering time.
• They promote cell expansion and contribute to overall plant growth.

Auxin

• Auxin signaling is essential for embryogenesis and defines the later growth axes of the plant.
• Auxin action is shaped through polar auxin transport and determines root system growth and branching pattern.
• Auxin accumulation is essential for lateral organ formation and floral organ primordia.

Brassinosteroids

• Brassinosteroids have been reported in almost all plant tissues, with highest levels found in seeds, pollen, and young growing tissues.
• They act largely postembryonically, promoting general plant growth via cell elongation, vascular differentiation, and reproductive development.

Ethylene

• Ethylene promotes ripening of many types of fruit, leaf abscission, and the triple response in seedlings.
• It enhances the rate of senescence, promotes root and root hair formation, and promotes flowering in the pineapple family.

Abscisic Acid

• Abscisic acid inhibits growth, promotes stomatal closure during drought stress, and promotes seed dormancy.
• It also inhibits early germination, promotes leaf senescence, and promotes desiccation tolerance.

Cytokinins

• Cytokinins regulate cell division in shoots and roots, modify apical dominance, and promote lateral bud growth.
• They also promote movement of nutrients into sink tissues, stimulate seed germination, and delay leaf senescence.

Jasmonates

• Jasmonates regulate fruit ripening, floral development, pollen production, tendril coiling, root growth, and seed germination.
• They are produced in response to herbivory and pathogen invasion.

Strigolactones

• Strigolactones promote seed germination, control apical dominance, and attract mycorrhizal fungi to the root.

Explore the role of plant hormones in regulating plant growth and development, from cell elongation to organ formation. Learn about the complex crosstalk between hormone signalling pathways and their impact on plant development.