Strigolactones: A new player in regulating adventitious root formation

Adventitious roots (AR) arise from nonroot parts of plants, in response to stress and wounding. Gas transport and mineral-nutrient uptake are the key functions of adventitious rooting. Phytohormones play a significant role in the formation of adventitious roots. While auxin and ethylene promote AR formation, cytokinin, gibberellin, jasmonic acid, and abscisic acid inhibit AR formation. Strigolactones are a special class of phytohormones, earlier classified as the repressors of AR development, are now known to modulate species-specific responses. The interaction of strigolactones (SL) with the other hormones regulates the development of AR. Besides regulating AR formation, SL is important for hyphal branching, seed germination, leaf shape and senescence, and secondary growth of plants. Furthermore, SLs act by imparting tolerance to biotic stress conditions, like root-knot nematode and leafy gall syndrome, and abiotic stress responses to drought, chilling, and salinity stress. Therefore, the present chapter is primarily focused on strigolactones-mediated adventitious roots formation.