Strigolactones interact with other phytohormones to modulate plant root growth and development

Strigolactones (SLs), which are biosynthesized mainly in roots, modulate various aspects of plant growth and development. Here, we review recent research on the role of SLs and their cross-regulation with auxin, cytokinin, and ethylene in the modulation of root growth and development. Under nutrient-sufficient conditions, SLs regulate the elongation of primary roots and inhibit adventitious root formation in eudicot plants. SLs promote the elongation of seminal roots and increase the number of adventitious roots in grass plants in the short term, while inhibiting lateral root development in both grass and eudicot plants. The effects of SLs on the elongation of root hairs are variable and depend on plant species, growth conditions, and SL concentration. Nitrogen or phosphate deficiency induces the accumulation of endoge-nous SLs, modulates root growth and development. Genetic analyses indicate cross-regulation of SLs with auxin, cytokinin, and ethylene in regulation of root growth and development. We discuss the implications of these studies and consider their potential for exploiting the components of SL signaling for the design of crop plants with more efficient soil-resource utilization.(c) 2022 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Strigolactones (SLs), which are biosynthesized mainly in roots, play important roles in modulating various aspects of plant growth and development. They are cross-regulated with auxin, cytokinin, and ethylene in regulating root growth and development. SLs regulate primary root elongation and inhibit adventitious root formation under nutrient-sufficient conditions. In the short term, SLs promote seminal root elongation and increase adventitious root numbers in grass plants, while inhibiting lateral root development in both grass and eudicot plants. The effects of SLs on root hair elongation vary depending on plant species, growth conditions, and SL concentration. Nitrogen or phosphate deficiency leads to the accumulation of endogenous SLs and modulates root growth and development. Genetic analyses suggest the cross-regulation of SLs with auxin, cytokinin, and ethylene in root growth and development. The findings have implications for designing crop plants with improved soil-resource utilization.