morphogenesis in plant

 Morphogenesis in plant

Development of any plant organism into an organised integrated whole involving successive vegetative and reproductive growth phases is through growth and differentiation of cells, tissues and organs. The development occurs in the primary and secondary embryonic(meristematic) tissue which appear homogenous, but not so morphogenetically and histochemically. The primary kind is localised at the apices of main shoot and root also those of lateral buds roots including marginal meristems of leaves and the intercalary regions. The secondary kind of embryonic tissue occurs as lateral cambia of stelar and extra stelar regions of the shoot and root regions and also as wound cambia. Formation of the former kind of meristems is possible only on exposure to the physical environmental factors, which happens on seed germination and during the seedling growth. Even the entire globular embryo which gives rise to tissues and organs of the mature embryo is embryonic. It is often called as diffuse meristem. Entire developmental processes which begin in these embryonic tissue areas, are basically governed by the morphogenetic factors and phenomena.

There are two kinds of factors implied in morphogenesis. They are 1) internal biochemical factors present in the biological embryonic material of the plant organism, and 2) external environmental physical factors. The phenomenon are the behavioral tendencies which are expressed through these biological, but embryonic materials. The morphogenetic manifestations of plant organic pattern are the outcome of varied phenomena. Even the first embryonic cell, zygote is the starting material for their expressions.

Morphogenetic factors

Biochemical internal factors: Any embryonic tissue is endowed with complexity of these in the form of cell constituents namely:

1. Cell wall materials and membrane systems causing differentiation through selective permeability and internal tissue patterns in the organism.
2. Cytoplasm having growth and growth regulating substances, and organelles constituting physiological environment to the nucleus.
3. nucleus having genetic set up of the plant organism. Such an embryonic tissue is biologically responsive area to the physical factors which bring stimulatory impact on the former in causing growth and differentiation of tissues and organs

External physical factors: These are environmental in nature namely light, temperature, and water and gravity which are environmental physical factors. These exert stimulatory influence on the  apical embryonic tissue areas which readily response giving rise to organic pattern of the shoot and root of the plant organism. Light temperature and humidity influences the development of shoot area where as water, temprature and gravity influence that of the root area.