Tag: development of plants

Phytochrome is blue colored pigment present in the plants. It is a photoreceptor chromoprotein. It is mainly found in flowering plants. These are responsible for flowering. It mainly absorbs red and far-red radiation in plants and induces flowering process.

Phytochromes are photoreceptor found in plants that detects light. The different phytochromes are involved in different biological responses to red light. P$ _r$ is inactive form whereas P$ _{fr}$ is active form of phytochrome. When exposed to red light,  P$ _r$ is converted to P$ _{fr}$. This active form then initiate many biological processes in plants.

Phytochromes are the hormones that are light dependent and are bluish green pigments that are involved in the developmental processes. They are light dependent and activates the inactivated form of phytochrome. They sometimes are useful in seed germination and cell elongation but stops the elongation of the stem when getting too exposed to far-red light and get inactivated.

In callus culture, cell division in explant (differentiated mass of mature cells) forms and callus. Callus is an irregular unorganized and undifferentiated mass of actively dividing cells. The process is called dedifferentiation.

In plants, apical meristems divide and differentiate to perform a specific function. This phenomenon is called as differentiation. Sometimes, the differentiated cells in plants regain the capacity to divide under certain conditions. This phenomenon is called as dedifferentiation. An interfascicular vascular cambium is an example of dedifferentiation. During dedifferentiation, certain cells lose the capacity to divide and becomes mature. This phenomenon is called as redifferentiation.

Plants require four factors for its growth like:-

1. Extrinsic factors are those factors like light, water, temperature, availability of gases is the abiotic or environmental factors that control the growth of a plant. These are not controlled by the plant.
   
2. Intrinsic factors like growth regulators are released by the plant and are in direct control under the plant. They regulate process like cell differentiation, cell division etc.
   

The phonomenon of generation of whole plant by single cell is totipotency.It is the characteristic of plants mostly. When a plant of defferentiated tissue is cultured in a nutrient medium. Cells that are not dividing or are at resting stage undergo some changes and attain dividibility and become meristematic again. The process of reversion or regaining of meristematic activity to form callus is known as dedifferentiation while redefferentiation is the process in which the cell gains its specialization again.

Vivipary means that seed remains attached to the plant even during germination. It is an undesirable character for annual crops as they are not able to store under normal condition for coming years.