Do Plants Go Through Teenage Drama

August 2023

By: Mohana Priya.T

Hormones!

Teenagers with their mood swings, sudden anger and change in behaviour usually blame the change of hormones in their body. (If the lamp broke because I kicked it with anger, blame the hormones not me!) Growth in height, skin colour, excretion and even reproduction are controlled by various hormones in our body.

We know that hormones are very important in our body, but what about other living organisms on our earth? For example , What about Plants? The organism which forms the base of any food chain, without which none of the other life on earth can survive surely should have some mechanism for their survival and growth...

You will be surprised to know that they do have Hormones! (Well, they don't go through a teenager phase like humans, so it's safe to say that we don't need to worry about 'moody' plants) Plants have various hormones which control their growth, fruiting, and death. We will be talking about each one of them in this blog.

Let's start:

Auxins

• Discovered by Went

• Helps in elongation of the stem and roots

• Promotes cell elongation

• It causes apical dominance (growth of buds at the tip of the plant)

• Does not allow the abscission of leaves and fruits ( detachment or falling of leaves and fruits)

• Causes plants to grow towards light (bend towards the light)

Gibberellins

• Helps in breaking seed dormancy (inability of seed to germinate even in the presence of all favourable conditions)

• Helps in seed germination

• Breaks bud dormancy (promotes flowering in some plants even under unfavourable conditions)

• Controls fruit growth and development in apple and pear

Cytokinin

• This hormone acts in conjunction with (together with) auxins

• When the Auxins level is high and Cytokinin low -- Root formation takes place

• When the Auxins level is low and Cytokinin high -- Shoot formation takes place

• The ratio of cytokinin to auxins controls cell differentiation

• Promotes cell division

• Helps in growth in thickness (secondary growth)

• Suppresses apical dominance (Antagonistic affect of Auxins)

• Can retards or delay ageing in plants (senescence - death phase) (The Plant's personal Anti-Aging serum!)

Ethylene

• This hormone is a growth inhibitor

• A high concentration of Auxin induces Ethylene formation

• Promotes fruit ripening

• Accelerates abscission of leaves, flowers, and fruits (Antagonistic effect of Auxins)

• Causes ageing (senescence) ( Can you guess which hormone opposite is this?)

• Inhibits stem elongation and stimulates transverse expansion -- because of which the stems look swollen

Abscisic Acid

• Also a growth inhibitor

• Functions against auxin and gibberellin

• Increases seed and bud dormancy

• Reduces transpiration by closing stomata and wilting of leaves under water-scarce conditions -- Called the Stress hormone. (The cortisol of plants!)

• Stimulates formation of abscission zone (the part where the leaf or fruit is attached to stem -- makes it easier to fall)

• Causes senescence (Antagonist to Cytokinin)

We have so much in common with the other living organisms on Earth, after all, we are derived from the same source (stardust) and are dependent on the same planet.

There is a lot into this mysterious connection which can solve the primal questions of our origin and our future. We just need to continue looking...