H 2 O 2 , NO, and H 2 S networks during root development and signalling under physiological and challenging environments: Beneficial or toxic?

Hydrogen peroxide (H 2 O 2 ) is a reactive oxygen species (ROS) and a key modulator of the development and architecture of the root system under physiological and adverse environmental conditions. Nitric oxide (NO) and hydrogen sulphide (H 2 S) also exert myriad functions on plant development and signalling. Accumulating pieces of evidence show that depending upon the dose and mode of applications, NO and H 2 S can have synergistic or antagonistic actions in mediating H 2 O 2 signalling during root development. Thus, H 2 O 2 -NO-H 2 S crosstalk might essentially impart tolerance to elude oxidative stress in roots. Growth and proliferation of root apex involve crucial orchestration of NO and H 2 S-mediated ROS signalling which also comprise other components including mitogen-activated protein kinase, cyclins, cyclin-dependent kinases, respiratory burst oxidase homolog (RBOH), and Ca 2+ flux. This assessment provides a comprehensive update on the cooperative roles of NO and H 2 S in modulating H 2 O 2 homoeostasis during root development, abiotic stress tolerance, and root-microbe interaction. Furthermore, it also analyses the scopes of some fascinating future investigations associated with strigolactone and karrikins concerning H 2 O 2 -NO-H 2 S crosstalk in plant roots.