Role of Strigolactones: Signalling and Crosstalk with Other Phytohormones

Abstract

Plant hormones play important roles in controlling how plants grow and develop. While metabolism provides the energy needed for plant survival, hormones regulate the pace of plant growth. Strigolactones (SLs) were recently defined as new phytohormones that regulate plant metabolism and, in turn, plant growth and development. This group of phytohormones is derived from carotenoids and has been implicated in a wide range of physiological functions including regulation of plant architecture (inhibition of bud outgrowth and shoot branching), photomorphogenesis, seed germination, nodulation, and physiological reactions to abiotic factors. SLs also induce hyphal branching in germinating spores of arbuscular mycorrhizal fungi (AMF), a process that is important for initiating the connection between host plant roots and AMF. This review outlines the physiological roles of SLs and discusses the significance of interactions between SLs and other phytohormones to plant metabolic responses.

Keywords: arbuscular mycorrhizal fungi; carotenoids; photomorphogenesis; physiological roles; plant metabolism; seed germination.

Figure 1

Roles of strigolactones in plant architecture.

Figure 2

Overview of the SL signalling pathway [Modified from Wang et al. (121)]

Figure 3

Cross-talk between SLs and ABA [Modified from Ruyter-Spira (55)]

Figure 4

Crosstalk mechanisms between SLs, auxin and cytokinin in root tips. Brown arrows show auxin flux while black arrows and lines show assumed regulation pathways. [Figure adapted from Perilli (115), Koren (114) and Ruyter-Spira (55)]