In plants, genes can be divided into inducible and constitutive based on how they are expressed.
Constitutive genes are always active.
They are expressed all the time because the plant constantly needs the proteins they produce. These genes control basic life functions such as respiration, photosynthesis, and cell maintenance.
For example, genes that make enzymes for energy production or proteins that build cell structures are constitutive.
Inducible genes are active only under certain conditions.
They are switched on (induced) or off (repressed) in response to specific signals like light, stress, hormones, or pathogens. For example, when a plant faces drought, stress-related genes are induced to produce protective proteins. Similarly, defense genes are activated when a pathogen attacks.
In short, constitutive genes work all the time for normal plant function, while inducible genes are turned on only when needed to help the plant respond to environmental or internal signals.