Plant Growth and Development

• Development - The attainment of size by virtue of growth and architectural style by morphogenesis (differentiation of cells into tissues, organs and organisms)
• Aspects of development

  1. Growth
  2. Differentiation
  3. Organization
• Growth

  • the irreversible increase of cell number, and essentially its dry mass or weight
  • increase in size does not mean an increase in growth.
• Growth curve

  • Cells/organs show a definite pattern of growth

  A) Lag

  B) Logarithmic

  C) Stationary

  
• Differentiation

  • Reflects the orderly processes by which genetically identical cells become different, forming specialized tissues and organs
  • The reflection of change in the cell’s biochemical program, controlled by developmental genes
• Dedifferentiation

  • Important in the repair of injury, where cell near damaged sites become totipotent and reprogram their development
• Dedifferentiation

  • the reversal of the cell specialization
• Organization

  • orientation and integration of differentiated cells in space together with regulated growth whole plan
• Morphogenesis

  • the orientation and integration of differentiated cells in space together with regulated growth, and the consequent attainment of form and structure of the complete organism.
• development

  1. growth
  2. differentiation
  3. pattern formation
  4. morphogenesis
• development

  • Plants, develop according to a predetermined genetic blueprint
  • Expression is greatly influenced by signals received from the external environment
  • Plants are always undergoing development.
• Localization of Growth

  • Essential characteristics of organisms
  • At cellular level
• Localization of Growth

  
  

  Essential characteristics of organisms

  • take up relatively simple substances from environment and synthesize these to complex substances
• Localization of Growth

  
  

  At cellular level

  • increase in living material leads to increase in cell size and ultimately cell division complex process in multicellular organism
• Localization of Growth

  • Growth is restricted to certain embryonic regions called the meristems
• Meristems

  • Where plant growth occurs
  • Site of repeated cell division of unspecialised cells
  • Cells differentiate, and become specialised in relation to the function they will perform
• Basic Structures involved in Plant Growth and Development

  • Embryo
  • Meristems
• Basic Structures involved in Plant Growth and Development

  • Embryo
  • Cotyledons
  • shoots
  • root apical meristems
• Basic Structures involved in Plant Growth and Development

  • Meristems
  • Shoot
  • Axillary root (apical and lateral)
  • Floral
  • Cambiums (cork, vascular)
• Types of Meristems

  • Apical
  • Lateral
  • Intercalary
• Types of Meristems

  • Apical
  • tips of roots and shoot
  • site of primary growth in a plant
• Types of Meristems

  • Lateral
  • side portions, arising from the cambium (base of nodes and stems), responsible for secondary thickening of the stem and roots
• Types of Meristems

  • Intercalary
  • inserted between regions of differentiated tissues
• Types of Growth

  1. Indeterminate (ricebean, winged bean)
  2. Determinate (corn, rice, mungbean)
• Types of Growth

  • Indeterminate (ricebean, winged bean)
  • apical meristems of the roots and stems remain permanently embryonic over long periods
• Types of Growth

  • Determinate (corn, rice, mungbean)
  • other plant parts (leaves, flowers, fruits) are embryonic for limited period before the plant reaches maturity, have precise morphology and definite number of parts
• Internal Growth Mechanisms

  • Correlation Effect
  • Organ Differentiation
• Internal Growth Mechanisms

  Correlation Effect

  • The regulatory effects exerted by one part of the plant on the growth or development in another part
• Internal Growth Mechanisms

  Organ Differentiation

  • As shoot increases in bulk, the size of the root system becomes proportionately larger
  • Reduction in vegetative growth when the plant is fruiting
  • Stimulation of fruit growth by hormones produced in the developing seeds
  • Stimulating effects of buds/leaves on the rooting of stem cuttings