A SEMINAR ON

Cellular responses to environmental signals in plants

BY-

MISS HUMA NAZ SIDDIQUI (ASST.

PROF.)

G.D. RUNGTA COLLEGE OF SCIENCE AND TECHNOLOGY KOHKA KURUD ROAD BHILAI, 490023

Cellular responses to environmental signals in plants

SYNOPSIS

1. INTRODUCTION:-2. DEFINATION:-3. SIGNALING IN PLANTS AND ANIMALS:-4. SIGNAL MOLECULES:-5. CHEMICAL SIGNALS FOR COMMUNICATION:6. RECEPTORS:-A.) INTRA CELLULAR RECEPTORS:- B.) EXTRA CELLULAR RECEPTORS:-7.CHEMICALS OF SIGNALING:-A.) Auxins B.) GA C.)ABSICCIC ACID D.) ETHYLINE8. SIGAL TRANSDUCTION IN PLANTS:-9. EFFECT OF LIGHT:-10. CALCIUM SIGNALING PATHWAY:-11. MECHNISM OF CELL SIGNALING:-12. ADVANTAGE OF CELL SIGNALING:-13. IMPORTANCE OF CELL SIGNALUNG:-14.CONCLUSION:- 15. REFRENCE:-

Plants have the ability to sense and respond to a host of stimuli increasing their chances for survival and reproduction.

All organisms including plants, have the ability to receive specific environmental and respond to them in ways that enhance survival and reproductive success.

The process of communication between cells, in Which the signaling cell produces a specific signal molecule that Is detected by the target cell is described as cell signaling.

The process of converting extra cellular signals that carry specific informations into cellular responses is called signal transduction.

Plants have specific responses to specific stimuli. These responses improve their chances of survival and reproduction

Signals whether internal or external are first detected by receptors, proteins that change shape in response to a specific stimulus

Cellular responses to environmental signals in plants

Introduction

1

In plants, as in animals, cells are in constant communication with one another.

Cellular responses to environmental signals in plants DEFINAION OF SIGNALING

Every living plant cell and animal cell is surrounded by a membrane. These cellular membranes contain receptor molecules that serve as the cell’s eyes and ears, and help it communicate with other cells and with the outside world.

Fig.1:-cellular response of a plant 2

Plant cells communicate to coordinate their activities in response to the changing conditions of light, dark, and temperature that guide the plant's cycle of growth, flowering, and fruiting.

Plant cells also communicate to co-ordinate what goes on in their roots, stems, and leaves.

Cellular responses to environmental signals in plants

Introduction

fig.2:- structure of cell signaling in whole plant 3

Animals and plants have cell-surface receptors for cell signaling. Whereas most cell-surface receptors in animals are G-protein-linked, most found so far in plants are enzyme-linked.

Largest class of enzyme-linked receptors in animals is receptor tyrosine kinases, this type of receptor is extremely rare in plants.

Even though they contain many cytoplasmic tyrosine kinases, and tyrosine phosphorylation and dephosphorylation have important roles in plant cell signaling.

plants seem to rely on a great diversity of transmembrane receptor serine/threonine kinases, which are distinct from this type of receptor used by animal cells.

Like the animal receptors, however, they have a typical serine/threonine kinase cytoplasmic domain and an extracellular ligand-binding domain.

The most abundant types identified so far have a tandem array of extracellular leucine-rich repeats and are therefore called leucine-rich repeat (LRR) proteins

Cellular responses to environmental signals in plants SIGNALING IN PLANTS AND ANIMALS 4

Cellular responses to environmental signals in plants SIGNALING IN PLANTS AND ANIMALS Fig.3:-INTERNAL STRUCTURE OF CELL

SURFACE5

Signal

molecules

Signals molecules are chemically heterogenous compounds.

These molecules are divided into two categories-

A. Membrane bound and

B. Secretory molecules

Membrane bonds signal molecules remain bound to the surface of the cells and mediate contact dependent signaling.

signal molecules are secreted by signaling cells.

secreted extracellular signal molecules are further divided into three general categories based on the distance over which signals are transmitted: endocrine, paracrine and autocrine signal molecules

Example of signal molecules that interact with cell surface receptors

Epinephrine, non-epinephrine, insuline, ACTH.

Cellular responses to environmental signals in plants

6

It has been discovered that plants use chemical signals for communication. Some of these substances are released from leaves, fruits and flowers and various roleplaying in plant development and survival. Plants also communicate with insects. Example, corn, cotton and snuff under attack by caterpillars release chemical signals that simultaneously attract parasitic wasps to kill caterpillars and discourage moths lay their eggs in plants.

Cellular responses to environmental signals in plants CHEMICALS

FOR

COMMUNICATION

Fig.4:- A plant use chemical for communication. 7

Receptors

Cellular responses to environmental signals in plants

Lipid-soluble hormones, such as the steroid hormones, diffuse across the plasma membrane and bind to intracellular receptors .

Intra cellular receptors:-

Fig.5:- Intra cellular receptors of plant 8

Extra cellular receptors:- Many signal molecules are too large or insoluble to pass through the plasma membrane.

These signal molecules bind to specific cell surface, or extracellular, receptors in the plasma membrane of target cells.

Extracellular receptors are trans membrane proteins that have two distinct regions of activity, an extracellular ligand-binding domain and an intracellular signaling domain.

There are many different members of this family of extracellular receptors.

Cellular responses to environmental signals in plants Extra cellular receptors 9 Fig.6:-Show extra cellular receptors in a plant.

Plants respond to light, for they have receptors and after absorption they transducer through various chemicals to initiate transcription for flowering, see/grains

Auxins - they are synthesized they are translocated and act on cells via auxin binding Poteins, which rfegulate its downstream responses.

GA -synthesized in leaves translocated and bring about changes either in flowering or seed/ grain germination

Ethylene - one gaseous substance generated within the plant and it has a tremendous effect on plant curvature, fruit ripening.

Abscissic acid -responds to water conditions or drought and brings about changes in stomata closing or induce ripening and hasten falling of the leaves and flowers and fruits. 

Cellular responses to environmental signals in plants CHEMICALS OF SIGNALING

10 Fig.7:- Chemicals of signaling network in

plants

Cellular responses to environmental signals in plants SIGNAL TRANSDUCTION IN PLANTS

 Plants unlike animal systems are stationary but they react to environmental conditions and soil factors.

In plants affect are light, temperature, moisture in the atmosphere, soil water, soil minerals, and toxic elements. 

Green plants respond to duration of the light in day-periodism; plants sense the day length and prevailing temperature they produce flowers, or undergo hibernation in their own ways and means.

 All living cells, whatever kind and creed they belong, they do communicate with each other. 

Plants respond to light, for they have receptors and after absorption they transducer through various chemicals to initiate transcription for flowering

12

Light has tremendous effects on cellular activities including light triggered photosynthetic reactions, vision, photoperiodic induction of floweringcircadian rhythm and many others. 

In all these cells require light absorbing pigments such as chlorophyll/protein complex, phytochrome/protein complex, phototropin-protein complex;

they inturn execute downstream reactions such as light harvesting and transducing the same to generate energy rich ATP and NADP molecules, activating genes for flower development and inducing photo-curvature (phototropism) movements respectively.

Cellular responses to environmental signals in plants

Effect of light

13 Fig.8:- Effect of light in plants.

Cellular responses to environmental signals in plants Calcium signaling pathway

Calcium serves as a versatile messenger in many adaptation and developmental processes in Plants Ca2 + signals are represented by stimulus-specific spatially and temporally defined Ca2 + signatures.

These Ca2 + signatures are detected, decoded and transmitted to downstream responses by a complex toolkit of Ca2 + binding proteins that function as Ca2 + sensors. Ca2 +-mediated signal transduction processes in plant cells.

Examples of signal transduction processes :-

mediated by CaMs, CDPKs and CBL–CIPK complexes together with their respective target proteins, which were investigated in different plant species (indicated by the acronyms: At, Arabidopsis; St, potato; Nt, tobacco).

14

Cellular responses to environmental signals in plants Calcium signaling pathway

Fig.9:- Calcium signaling pathway in plants.

15

Cellular responses to environmental signals in plants MECHNISM OF CELL SIGNALING

Three process are takes place:-

1) Recognize an outside signal,

2) Transport that signal across the cell's membrane and 3) Initiate the reading of the signal inside the cell and then initiate the cell's response to that signal. (collectively known as transmembrane signaling)

Transmembrane signaling in animal cells has been significantly more studied and observed than that in plant cells.

Transmembrane signaling in plants, Hothorn and colleagues observed the steroid, shown in yellow attach to a membrane-bound receptor, shown in blue. This attachment enabled the steroid's counterpart--a co-receptor protein, shown in orange--to bind to the blue receptor.

Once bound , the orange co-receptor and the blue receptor become glued together by the yellow steroid, allowing their intracellular domains to touch and initiate communication.

16

Cellular responses to environmental signals in plants MECHANISM OF CELL SIGNALING

Fig.10:- Mechanism of cell signaling in plant17

Cellular responses to environmental signals in plants ADVANTAGE OF CELL SIGNALING

Cell signaling is very crucial to make sure proper timing of communication between cells.

This is the most important selective advantage of cell signaling.

It maintains the link between different cells of an organisms and ensures proper functioning of the organism.

Cell signaling is part of a complex system of communication that governs basic cellular activities and coordinates cell actions.

18

Cellular responses to environmental signals in plants

Summary

Cell signaling is very important for a living organisms, in plant it is also play a important role. Cell signaling means transfer of signal s from one to an other. This process is due to different types of chemicals , hormones and signal. Cell signaling- may be it for growth, defiance and an other. In signaling different pathways are also work. Cells have sincere to since the signals which are come from internal or external cellular receptors. This receptors bind with cell membrane.

20

Cellular responses to environmental signals in plants

REFRENCE

1. CELL AND MOLECULAR BIOLOGY, 2003 P.K. GUPTA 2. CELL AND MOLECULAR BIOLOGY 2007 KARP

GERALD

3. THE CELL 2009 COOPER. M. GEOFFREY

THANK YOU