Plant Tissues

Introduction 

An introduction to plant tissue culture is important for understanding several processes that take place in plants. A cell is the basic structural and functional unit of life. A tissue is a group of cells that are similar in structure and perform the same function. These functions include transportation, protection, reproduction, etc.

Classification of Plant Tissues

Tissue culture in plants can be classified on the basis of the part of the plant they are present in or on the basis of the kind of cells they contain.

On the Basis of Location in Plant

• Epidermal tissues: Epidermal tissues are a single layer of cells that cover the exterior of a plant
• Ground tissues: Ground tissues are the tissues that cover a plant’s interior
• Vascular tissues: Inside the plant, vascular tissues transport water and dissolved substances

On the Basis of the Kind of Cells

1. Meristematic Tissue

These plant tissues can be divided further on the basis of origin, position and function.

On the basis of origin:

• Promeristem
• Primary Meristem
• Secondary Meristem

On the basis of position:

• Apical Meristem
• Lateral Meristem
• Intercalary Meristem

On the basis of function:

• Protoderm
• Procambium
• Ground meristem 

2. Permanent Tissues

Permanent tissues are of two kinds, each with its own subtypes: simple plant tissues and complex plant tissues.

Simple plant tissues

• Parenchyma
• Collenchyma
• Sclerenchyma

Complex plant tissue

• Xylem
• Phloem

Meristematic Tissue

These tissues have the ability to divide quickly in order to grow and hence are also known as dividing tissue. They contribute to the vegetation’s growth significantly. These cells are responsible for the plant’s growth in length and diameter. Meristematic cells are live cubical cells with a large nucleus. There are no intercellular gaps in these cells since they are neatly packed. Intercalary, lateral, and apical meristems are classified according to the part where the meristematic tissues reside. The cells in this tissue contain abundant cytoplasm, thin cellulose walls, and conspicuous nuclei due to their high activity. They do not have vacuoles.

Types of meristematic tissue on the basis of origin

Promeristem

• These are the meristematic tissues that are the most recent.
• They grow out of the embryo.
• They are frequently found around the base and at the terminals of the shoots.

Primary meristem

• The promeristem is the source of their development.
• The cells of these tissues are constantly dividing.
• These tissues grow and mature into permanent tissue.

Secondary Meristem

• They emerge from the main meristem.
• The secondary meristem is formed by them.

Types of Meristematic Tissue on the Basis of Position

Apical meristem: The apical meristem is one of the tissue cultures in plants. It is found at the growing points of stems and roots, and it extends the stem and root’s length.

Lateral meristem: Because of the lateral meristem, the girth of the stem or root grows (cambium).

Intercalary meristem: The meristem at the base of the leaves or internodes (on each side of the node) on twigs is known as the intercalary meristem. The function of the intercalary meristem is to increase the size of internodes.

Types of meristematic tissue on the basis of function

Protoderm

• It is the outer layer of the tissues.
• Its job is to keep plants safe from mechanical shocks.

Procambium

• This is found in the tissues’ deepest layer.
• It connects the xylem and phloem.
• It aids in the movement of water and nutrients throughout the plant.

Ground meristem

• The cells of these tissues are large and have thick walls.
• They are in charge of the pericycle, cortex, and pith formation.

Permanent Tissues

The cells that cannot divide themselves anymore are found in permanent tissues. They can, however, provide the plant with suppleness, flexibility, and strength.

Simple Permanent Tissue

Simple permanent tissues are all the same. They have a common function, origin, and structure are classified as a single cell type.

Parenchyma

• These are polygonal cells that are living and feature a large central vacuole, as well as intercellular gaps between them. Pith and ground tissue are created by parenchymatous cells
• Chlorenchyma is a kind of parenchyma that contains chloroplasts. Photosynthesis is aided by the chlorenchyma
• Aerenchyma is a kind of parenchyma that has large air gaps. The aerenchyma’s primary function is to provide buoyancy
• In vegetables and fruits, certain parenchymatous cells serve as starch storage chambers

Collenchyma

• These are live cells that have been stretched out and have minute intercellular gaps
• Cellulose and pectin make up their cell walls
• Collenchyma is present on the margins of stems and leaves, and it provides plants with structural flexibility and mechanical support

Sclerenchyma

• These tissues are stiff and lifeless
• Between the cells, there is no gap
• They are typically found in the coverings of nuts and seeds
• Their rigidity gives the plant its strength
• Because the cells have very thick walls, they are stiffer

Complex Permanent Tissue

The complex tissues are crucial since they are in charge of the plant’s transportation system. It consists of phloem and xylem. They make it easier for water, food, and nutrients to move around the plant.

Xylem

• This tissue is responsible for transporting liquid materials throughout the plant
• The transit begins from the root and continues until each leaf is reached
• It provides lignin-based components to sustain the plant
• Vessels, tracheids, xylem parenchyma, and xylem fibres make up the xylem

Phloem

• This tissue aids in the movement of food throughout the plant
• Phloem fibres, sieve tubes, phloem parenchyma, and companion cells are some components of phloem

Conclusion

A well-maintained tissue system is critical for a plant’s survival. It enables them to thrive in terms of growth, development, and function. Each type of tissue plays a role in the plant’s life cycle in some way. It is critical to first comprehend them before moving on to the environment.