Introduction to Hormone No.4 Ethylene

Once again plant guru welcomes you to guru journey part 4!

Today, the hormone that you will be learning is...... ETHYLENE!! Ethylene, ethylene, ethylene, ethylene, ethylene, ethylene, ethylene, ethylene, ethylene, ethylene, ethylene~ This hormone stimulates the ripening of fruit, the opening of flowers, and the abscission (or shedding) of leaves in plants.

Cool fact: "Ethylene has been used in practice since the ancient Egyptians, who would gas figs in order to stimulate ripening. The ancient Chinese would burn incense in closed rooms to enhance the ripening of pears. In 1864, it was discovered that gas leaks from street lights led to stunting of growth, twisting of plants, and abnormal thickening of stems."

Effects

• Stimulates leaf and flower senescence (organic process of aging)
• Induces leaf abscission mainly in older leaves.
• Induces seed germination
• Induces root hair growth – this increases the efficiency of water and mineral absorption
• Stimulates epinasty – leaf petiole grows out, leaf hangs down and curls into itself
• Stimulates fruit ripening
• Induces the growth of adventitious roots during flooding
• Disease/wounding resistance
• Inhibits stem swelling or Stimulates cell broadening and lateral root growth
• Interference with auxin transport (with high auxin concentrations)

Of course the list may go on and on, BUT stay tune for the next chapter of guru journey!!

Introduction to plant hormone No.3 Cytokinin

• Cytokinins are a class of plant growth substances (plant hormones) active in promoting cell division, and are also involved in cell growth, differentiation, and other physiological processes.
  Read on to find out why!!
  
  Functions
  Cytokinin
  1) regulates the cell cycle
  
  2) Regulates tissue morphogenesis. The ratio of auxin : cytokinin in tissue culture medium determines root or shoot production
  
  3) Delays senescence and promotes nutrient uptake (delays senescence: eg slows the loss of Chl, RNA, protein, lipids)
  
  4) Promotes chloroplast maturation and cell enlargement in leafy cotyledons
  
  Effects




• Promotes growth;




• stimulates cell division;




• encourages growth in lateral buds;




• blocks leaf senescence
  

Did you know??
The effects of this hormone was first discovered through coconut milk in the 1940s.

Before I sign off, think about this : what would happen if there was no more cytokinin in the leaf? What would happen to it?

This is theplantdoctor signing off. The next time, we will explore ethylene, plant hormone no.4. Stay tuned for the next post!!

Introduction to Hormone No.2 Auxins

Welcome back to part 2 of our journey towards understanding more about how plant hormones work in our fellow plantlike friend's lives.

Today, I shall share with you something about the plant hormone, Auxins.

Auxins play an essential role in the coordination of many growth and behavioral processes a plant's life cycle.

Functions

To cause growth in the required domains, Auxins must preferentially be active in them(since Auxins are not synthesized everywhere). Each cell has the potential ability to do so, but Auxin synthesis will only be activated under specific conditions. For growth purposes, not only do Auxins have to be translocated toward the specific sites where they are needed, but there has to be an established mechanism to detect those sites. Translocation is driven throughout the plant body primarily from peaks of shoots to peaks of roots.

promote uniform flowering

promote fruit set

prevent premature fruit drop

Used in high doses, auxin stimulates the production of ethylene. Excess ethylene can inhibit elongation growth, cause leaves to fall (leaf abscission), and even kill the plant

It induces formation and organization of phloem and xylem. When the plant is wounded, Auxin can induce cell differentiation and regeneration of the vascular tissues.

Effects

The plant hormone stimulates cell elongation. It stimulates the Wall Loosening Factors, for example, elastins, to loosen the cell walls

It stimulates cell division if cytokinins are present

It induces sugar and mineral accumulation at the site of application.

So today, we have learnt about the plant's amazing ability to create and repair new cells. Imagine the great things we can do if we can harness this exceptional ability and apply it to the human anatomy. We can modify the hormone such that its effects can be quickly seen. Think of the impact it would have on medical science. Wouldn't it be cool if we could see our fresh new wound healing right before our eyes?

So I'll leave you to think along this line and maybe you can share with me how you think this particular hormones can revolutionize the way we live. Until next time, this is you plant guru.
Signing off.....

Today, lets learn something simple about Abscisic acid!!


Abscisic Acid

Abscisic (ABA)is a naturally occurring compound in plants. It is partially produced via the mevalonic pathway in chloroplasts and other plastids.

Functions of Abscisic Acid

Stimulates the closure of stomata in order to reduce transpiration and prevent water loss.
(water stress brings about an increase in ABA synthesis).

Inhibits shoot growth but will not have as much affect on roots, and may even promote the growth of roots.

Induces seeds to synthesize storage proteins.

Encourages seed dormancy by inhibiting cell growth – inhibits seed germination

Inhibits the effect of gibberellins(we'll explore this hormone in our fifth edition) on stimulating of new synthesis of a-amylase.

Decreases metabolism in response to a newly-developing deficiency of nutrient or adverse environmental condition, such that the condition becomes survivable at the new lower level of metabolism

Induces gene transcription especially for proteinase inhibitors in response to wounding which may explain an apparent role in pathogen(any disease-producing agent)
defense.

Man! Not only do humans and animals have this complex corrective system of homeostasis, even our plants possess this incredible mechanism.

So stay tune to learn more about plant hormones from yours truly, Doctor Guru!!

First of all, i would like all of you to know that there are basically 5 major classes of plant hormones,namely :
1.abscisic acid
2.auxins
3.cytokinins
4.ethylene
5.gibberellins
Each and every one of these hormones play a very specific and vital role in carrying out the plant's day to day functions. So in other words, they are extremely important and any abnormalities might lead to dire consequences.

What is a hormone?

As plants grow their genotype is expressed in the phenotype which is modified by the environmental conditions that they experience. Somehow the rates of growth and differentiation of cells in different parts of the plant are coordinated in response to these inputs.
There has to be communication between these levels: how does the plant receive and respond to environmental inputs or "signals"? What communication is there inside the plant to adjust growth and development to the environment?
When growing plants commercially we can ask similar questions:
what environmental input will produce the kind of growth that we want?
or can we modify the growth by applying a chemical regulator?
can change the genotype to achieve the kind of growth we want (by traditional breeding or by genetic manipulation)?
The answers to each of these questions depends on an understanding of how plant growth is regulated. Hormones in animals coordinate body functions by being produced in one place and acting in another. Plants do not have a circulatory system and "action at a distance" may not be a feature of plant hormones. They are molecules that are not directly involved in metabolic or developmental processes but they act at low concentrations to modify those processes.
There are five generally recognized classes of plant hormone, some of the classes are represented by only one compound, others by several different compounds. They are all organic compounds, they may resemble molecules which turn up elsewhere in plant structure or function, but they are not directly involved as nutrients or metabolites.

Plant Hormones

Greetings all,
I'm your plant Guru. I am fascinated with plants for they are so unique and special.
They seem to be all self sustaining. Self fulfilling. Self beautifying. Self providing. In other words, they can be considered, an independent nation.
I believe, that this special organism does not need any human interference but yet, can still continue to flourish with abundance. However, we being very possessive beings, cannot resist the temptation to add this amazing organism to our collection of "inventions".
Hence, the invention of what we call, "Plant Hormones".


Over the next few days, I shall share with all of you my vast knowledge and experiences with this particular hormone and all the things we have benefited from it. On your part, you can do some research of your own and share with me some of your own experiences. So, what are you waiting for, embark on this exciting trail with me and start posting your questions!!!