Ahtsham Khan Plant Physiology Presentation.pptx

the Bioplastic produced from wheat husk

1. Introduction to Plant Physiology Presentation# 01 Submitted By: Ahtsham Khan Submitted To: Dr. Samina Khalid Plant Hormones Nature Biosynthesis

2. CYTOKININ’S: There are a variety of growth regulators in plants just as in humans which regulate various metabolic processes. Cytokinin’s are a set of hormones that influence growth and the cell cycle in plants. The name 'cytokinin' comes from the fact that they modulate cell division or mitosis. Regulation of mitosis influences growth processes from the growing phase of seed germination to the declining phase of leaf senescence. The number of cytokinin’s also regulates the growth of the shoots, development of the embryo, flowers, and fruits plant-pathogen interactions.  

3. Structure of Cytokinin’s: Cytokinin’s are a group of plant hormones that play a critical role in regulating cell division and other developmental processes. They are synthesized from adenosine and are found in many plants, including tomatoes, cucumbers, and bananas. Chemical Composition : Cytokinin’s are a class of plant hormones that are predominantly derivatives of adenine. Functional Group : They contain an isopentenyl (or similar) side chain at the N6 position of the adenine ring. This side chain can be an isoprenoid, aromatic, or aliphatic in nature. Variants : There are various forms of cytokinin’s, including isopentenyl adenine (IPA), zeatin, dihydrozeatin , and their ribosides and other derivatives. These variants contribute to the diverse biological activities exhibited by cytokinin’s.

4. Chemical Structure of Cytokinin

5. INTERNATIONAL/LOCAL ALTERNATIVES There are the many functions of Cytokinin’s but on the type of Cytokinin’s and plant species the responses will vary. List of some of the known physiological effects caused by Cytokinin’s is listed below: It stimulates cell division. It stimulates morphogenesis (shoot initiation/bud formation) in tissue culture. It stimulates the growth of lateral buds-release of apical dominance. It stimulates leaf expansion resulting from cell enlargement. It enhances stomatal opening in some species. It promotes the conversion of E tioplast into chloroplasts via stimulation of chlorophyll.   Functions of Cytokinin’s:

6. Biosynthesis of Cytokinin’s in plants: The Biosynthesis of Cytokinin’s take place in following steps: Initial Step : Cytokinins are primarily synthesized in the root tips and developing seeds of plants. The biosynthesis begins with the formation of the initial precursor molecule isopentenyl pyrophosphate (IPP) via two distinct pathways, the Mevalonate (MVA) pathway in the cytosol and the Methylerythritol Phosphate ( MEP ) pathway in plastids. Activation of Precursors : The prenyltransferases , specifically isopentenyltransferases ( IPTs ) and dimethylallyltransferases ( DMATS ), catalyze the transfer of the isoprenoid side chain (derived from IPP) to the N6 position of the adenine ring of adenosine phosphates. Modification via Hydroxylation : The modified adenosine phosphates are then subjected to hydroxylation, often at the N9 position, by cytokinin-specific hydroxylases. These enzymes are responsible for introducing hydroxyl groups into the aromatic ring, producing various cytokinin derivatives.

7. Biosynthesis of Cytokinin’s in plants: Conjugation and Transport : The cytokinins are frequently conjugated with sugars, amino acids or other moieties to facilitate their storage and transport within the plant. Regulation and Localization : The biosynthesis of cytokinins is regulated at multiple levels including transcriptional, post-transcriptional, and post-translational regulation to ensure the spatial and temporal distribution of cytokinins within the plant. Biological Effects : Once produced, cytokinins play vital roles in regulating various plant growth and developmental processes such as cell division, shoot and root growth, leaf expansion, chloroplast development, and delay of senescence.  

8. Physiological Response of Cytokinin’s in Plants: Cytokinins are a class of plant hormones that play crucial roles in regulating various physiological processes in plants. Here are some key physiological responses of cytokinins in plants: Cell Division and Differentiation : Cytokinins stimulate cell division and differentiation, playing a fundamental role in plant growth and development. They promote the formation of new tissues and organs, including shoots, leaves, and roots. Apical Dominance: Cytokinins help overcome apical dominance, the inhibition of lateral bud growth by the apical bud. By promoting lateral bud outgrowth, cytokinins contribute to branching plants.

9. Physiological Response of Cytokinin’s in Plants: Gene Expression Regulation: Cytokinins influence gene expression related to various physiological processes, including cell cycle control, metabolism, and stress responses. They regulate the expression of genes involved in growth and development pathways. Root Growth and Nutrient Uptake: Cytokinins play a role in root growth by promoting lateral root development and enhancing nutrient uptake efficiency. They contribute to the overall root system architecture and help plants adapt to varying soil conditions.