The diversity of indole concerning its production and functional role has increased in both
prokaryotic and eukaryotic systems. The bacterial species produce indole and use it as a signaling molecule
at interspecies, intraspecies, and even at an interkingdom level for controlling the capability of
drug resistance, level of virulence, and biofilm formation. Numerous indole derivatives have been
found to play an important role in the different systems and are reported to occur in various bacteria,
plants, human, and plant pathogens. Indole and its derivatives have been recognized for a defensive
role against pests and insects in the plant kingdom. These indole derivatives are produced as a result of
the breakdown of glucosinolate products at the time of insect attack or physical damages. Apart from
the defensive role of these products, in plants, they also exhibit several other secondary responses that
may contribute directly or indirectly to the growth and development. The present review summarized
recent signs of progress on the functional properties of indole and its derivatives in different plant systems.
The molecular mechanism involved in the defensive role played by indole as well as its’ derivative
in the plants has also been explained. Furthermore, the perspectives of indole and its derivatives
(natural or synthetic) in understanding the involvement of these compounds in diverse plants have also
been discussed.
