Small Molecule Toolbox for Strigolactone Biology

Abstract

Strigolactones (SLs) are plant hormones associated with diverse developmental processes including plant architecture and stress responses. SLs are exuded to the soil as an ecological signal to attract symbiotic arbuscular-mycorrhizal fungi. This ecological mechanism is also used by parasitic plants to detect the presence of host plants and initiate germination. The functional diversity of SLs makes SL biology so extensive that a single methodology is not sufficient to comprehend it. This review describes the theoretical and practical aspects of the design of small molecule probes that have been used to elucidate the functions of SLs. The lessons from the development of small molecules to tackle the unique questions in SL biology might be instructive in the extending field of chemical biology in plants.

Regulation of biosynthesis, perception, and functions of strigolactones for promoting arbuscular mycorrhizal symbiosis and managing root parasitic weeds

“…These results clearly demonstrate that the structural requirements of SLs for these biological activities – germination stimulation of root parasite seeds, inhibition of shoot branching and induction of hyphal branching in AM fungi – are similar but different. Accordingly, it should be possible to develop SL agonists and/or antagonists specific to one of these biological activities . For example, a highly active and specific germination stimulant for Striga seeds, sphynolactone‐7, has been developed …”

“…Accordingly, it should be possible to develop SL agonists and/or antagonists specific to one of these biological activities. 39,40 For example, a highly active and specific germination stimulant for Striga seeds, sphynolactone-7, has been developed. 41 Introduction of a hydroxyl group to C4 of CL resulted in a reduction in hyphal branching activity, whereas 18-HO-CL was as active as CL.…”

“…3) was reported to bind to D14. 39,40 Interestingly, 2-MN and LD1 significantly differ in their skeletons but both compounds bind to the same protein, D14, indicating that a further search of different chemical libraries would likely identify novel SL-signaling inhibitors with distinct structures.…”

A Protoplast-Based Bioassay to Quantify Strigolactone Activity in Arabidopsis Using StrigoQuant

“…Due to their versatile and biological functions, and large chemical diversity, SLs have increasingly attracted researchers' interest. To unravel the mechanisms underlying their regulatory roles, shed light on their structure-activity-relationships and to elucidate their biosynthesis, molecular and quantitative tools are sorely needed [15][16][17]. Our recently developed sensor StrigoQuant can provide quantitative insights in the structural specificity and sensitivity of the SL perception complex towards various natural and synthetic SLs, using Arabidopsis protoplasts as an investigation system [12].…”

Tryptophan derivatives regulate the seed germination and radicle growth of a root parasitic plant,Orobanche minor

“…In the SL structure, the D-ring is the most critical component for the bioactivities of SL-related chemicals. Even when a molecule that is structurally unrelated to SLs is attached to the D-ring, these synthetic analogs often show SL-like bioactivities 4 . Consequently, we chemically synthesized a hybrid SL analog in which the D-ring moiety was attached to the carboxylic acid part of IAA (Fig.…”