Why are plants so sensitive to environmental changes? In this lesson, we explore signal transduction in plants and see how this helps plants adapt to the world around them.
Why shouldn’t you ever play poker in the jungle? Because there are too many cheetahs! Hey! Get it? Now, I think that joke’s funny, but how you reacted to it will influence whether or not I pursue a career in comedy.
Why? Because one of the first social skills we learn is to judge the signals being communicated by other people. This is reassuring. This means stay away. This means don’t ever try and tell jokes again.
Well believe it or not, cells actually have similar skills. Signal transduction is the process of changing cellular activity based on external signals. Basically, cells receive all sorts of signals from the world around them, from light to nutrients to temperature, and these prompt the cell to respond in a specific way. Signal transduction occurs in all sorts of living things, but lately one specific area has been gaining lots of attention. There may be no set of organisms on this planet more sensitive to environmental changes than plants, so studying them can unlock new information on this process. We’re simply too excited about plants to ‘leaf’ it alone. Okay, I’ll stop.
Alright, so let’s take a quick look at how this works. We start with a change in the environment. This could be light, temperature, a chemical or molecule introduced into the environment, or a change in available nutrients. This change is recognized by a special molecule on the cell membrane called the extracellular signaling molecule. In this case, ‘extra’ means ‘outside,’ so extracellular means from ‘outside the cell.
‘ Upon receiving the signal, this molecule activates a receptor that kicks off a series of biochemical chain reactions to create a response called a signal pathway. Different signals will activate different pathways. For example, red light waves are very important for regulating photosynthesis, so when plants sense red light waves through a receptor called a phytochrome, it kicks off the phytochrome transduction pathway, the end result of which is that the plant starts preparing for photosynthesis. In plants, these various signal pathways are responsible for a great number of things, from germination to flowering to the ripening of fruit to the growth of new roots.
Again, plants are extremely sensitive to environmental changes, and signal pathways are how they adjust to these changes.But, how do these changes actually occur? The signal pathways, the set of chemical reactions that occur when an extracellular signal is received, generally have a direct destination: the cell nucleus. The nucleus is where the cell stores its genetic information, and cell function is determined by the genes being transcribed or activated on the DNA. So in order to create a response to the signal, the cell needs to transcribe the appropriate genes.
That’s the goal of the signal pathways;to change the genes being transcribed in the cell nucleus so that the cell function can change to accommodate the new signals. If it’s springtime, certain cells need to have the genes activated that control flowering. If it’s a drought, different genes need to be activated to reduce water loss. The signal pathways create the chemical reactions needed to activate or silence the genes needed to make this happen.
Plant Signal Transduction
As anyone who has ever owned plants knows, plants can change a lot in response to various environmental changes. Modern researchers now think that a major portion of the plant genome is actually focused on creating these signal pathways.
I say that they think this because this is actually a relatively young field of research. The importance of signal transduction in plants was not truly appreciated until the advent of modern gene sequencing made it possible to start mapping the ways that different genes interact. There are still many questions that need answered, but as scientists sequence more and more genes it becomes more and more apparent that signal transduction and signal pathways play an integral role in the cellular function of plants. I guess you could say this is really the ‘root’ issue of plant development.
Signal transduction is the process of changing cellular activity based on external signals. This occurs in most living things and allows them to respond to major environmental changes, but perhaps no organisms take this more seriously than plants. Signal transduction occurs when external signals are received by a special molecule on the cell membrane called the extracellular signaling molecule that kicks off a series of biochemical chain reactions to create a response called a signal pathway. The end result is to change the genes being activated or silenced in the cell nucleus, thus changing the cell’s function. This is a growing field of research that is starting to take off in modern science. I guess you could say it’s really ‘flowering.’