Strigolactone, a key regulator of nutrient allocation in plants

Abstract

Strigolactones (SLs) are a group of terpenoid lactones that are derived from carotenoids. SLs have been found in a number of plant species and appear to serve several diverse physiological functions. SLs were first identified by their ability to stimulate seed germination of root-parasitic plants. Later, SLs were isolated as hyphal-branching inducers of arbuscular mycorrhizal fungi, which facilitate the uptake of soil nutrients by plants. Most recently, SLs (or their derivatives) were found to be a new class of plant hormones that inhibit shoot branching. Considering these three roles of SLs, it was unclear at first why communication signals in the rhizosphere would regulate shoot branching in the host plant. Recent reports, however, suggest that plants produce SLs in response to nitrogen and phosphorus deficiency, stimulating changes in plant shoot and root architecture that enable them to adapt to environmental conditions. Excess SLs produced in roots are released into the soil, where they stimulate the growth of arbuscular mycorrhizal fungi. These symbiotic fungi supply inorganic nutrients that can be used by the plant. This review paper focuses on the physiological roles of SLs as a key regulator of nutrient allocation in plants. © 2011 The Japanese Society for Plant Cell and Molecular Biology.