Sorgoleone unveiled: exploring its biosynthesis, functional perspectives and applications

Sorghum’s ability to exhibit allelopathy is linked to the secretion of lipophilic exudates from its roots. Sorgoleone, a member of the quinone class, constitutes a substantial part of these exudates. While studies typically focus on testing the exudate or crude extract, other compounds are also present, although in lesser quantities. Initially suspected molecular target sites affected by sorgoleone include photosynthetic and mitochondrial electron transport processes, along with p-hydroxyphenylpyruvate dioxygenase. Despite acting as a Photosystem II inhibitor in isolated chloroplasts, its impact on overall photosynthesis remains uncertain. Proposed mechanisms suggest inhibition of root H⁺-ATPase activity and water uptake, but questions persist regarding sorgoleone’s absorption, transportation to the shoot, and entry into chloroplasts. The spatial separation between sorgoleone exudation and its presumed site of action presents a notable challenge. This review delves into the characteristics and effects of sorgoleone, critically assessing its role in allelopathy. Furthermore, it explores the role of sorgoleone in signaling to facilitate the establishment of a symbiotic relationship between plants and arbuscular mycorrhizal fungi, as well as its impact on the microbiota. However, key questions regarding its mode of action, specific activity and selectivity, bioactive concentration, persistence and release in the rhizosphere, as well as its absorption and translocation, remain to be fully elucidated.