Stoller Academy Blog
THE PLANT’S TRUE “BRAIN”

One important mistake that people usually make, is thinking that plants are just sessile organisms that are green and produce the oxygen we breath. They are right in part, plants do produce oxygen through photosynthesis. However, they also do grow constantly, breath, move and “talk” to each other. How can plants be able to do all these things? The answer is simple, and just like us, they have a brain. A plant with a brain you might ask? How is that possible? The answer is quite simple, plants indeed do have brains, just not in the shape that first comes to mind. The plant’s “brain” is their roots.

The root system controls numerous and vital processes in the plant, even functioning as its “heart” by pumping water and nutrients across the whole plant. The roots are the main point of entry of water and minerals into the plant, after which these substances are transported into the rest of the plant’s tissues. The roots also act as a main organ for nutrient reserves, storing nutrients in many forms, such as sugars in sugar beets and starch as is the case of potatoes. Roots come in all shapes and sizes, such as fibrous roots like those of maize, adventitious roots of grass, tap-roots as carrots and tuberous roots like potatoes. Fun fact, did you know that there are aerial roots, which grow above ground? These are famously seen in mangroves.

 

           

 

But, how are the roots able to do all this? To answer this question, it is important to learn the basic morphology of the root.

The root is made up of 3 main regions:

  • Zone of cell division
  • Zone of cell elongation
  • Zone of cell differentiation

The tip of the root is protected by the root cap called the calyptra, just after that we can find the zone of cell division or the root apex meristem (RAM) where we can find stem cells that are continuously forming new types of cell. After that we find the cell elongation zone, where these new cells begin to grow in size until reaching the third zone called the differentiation zone, where these cells are differentiated into different types of cells in the root. Here we can find new ramifications and root hairs to increase the surface area for water and nutrient absorption.

Water can be absorbed in all the permeable membranes throughout the root surface. Older root regions may be impermeable to water uptake due to the deposition of suberin, an inert impermeable waxy substance present in the cell walls of corky tissues. Water uptake in roots occurs either through the symplast (1) or apoplast (2).

 

Source: Taiz & Zeiger, 2006

 

The symplast means that water is transported from cell to cell through the cytoplasms connected by plasmodesmata. Apoplastic water uptake means that the water passes around the cells without entering them, thus being a more energy effective method. When the water reaches the vascular tissues, it will be transported to the rest of the plant through the xylem. However, in older tissues, we can find the casparian strip, which is a thin impermeable layer that doesn’t allow water through to the xylem. So, in order to keep the root growing and forming new root hairs, it is important to keep the whole system young and continuously renewing itself. This is where new and innovative solutions come into play to stimulate this growth and maintain the whole root system young and active, thus taking care of the rest of the plant maintaining an optimal growth with the correct physiological and hormonal balance.

Plants are just like an iceberg, there is always more than meets the eye. The root system is one of the most important and vital parts of the plant, controls water and nutrient uptake, hormonal transport and most importantly, physiological balance throughout the plant. So, the next time you’re looking at your plants, remember, the green leaves, bright flowers and big fruits are all thanks to the roots, the true “brain” of the plant.

 

By Abbas Caballero

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