Sorgoleone enhances arbuscular mycorrhizal fungi (AMF) colonization in sorghum, optimizing phosphorus uptake and plant growth, with 20 µM identified as the optimal concentration for symbiotic efficiency.

Keywords: AMF colonization, P uptake, Rhizophagus clarus, Sorghum bicolor, plant growth

Arbuscular mycorrhizal fungi (AMF) form a mutualistic relationship with plant roots, significantly enhancing nutrient uptake, particularly phosphorus (P), in crops like sorghum, maize, and soybean. Researchers from Universidade Federal de São João del-Rei and Embrapa Milho e Sorgo examined the impact of sorgoleone, a root exudate produced by sorghum, on AMF colonization and plant growth by conducting a greenhouse experiment using sorghum genotype P9401 with low sorgoleone production and applying three doses of purified sorgoleone (20 μM, 40 μM, and 80 μM) to low-P soil. Plants were harvested after 45 days, with treatments including Rhizophagus clarus inoculation and a non-inoculated control. Results demonstrated that a 20 µM concentration of sorgoleone optimized mycorrhization, leading to increased plant biomass and P content under low-P conditions. Higher concentrations did not inhibit root growth but failed to enhance mycorrhization further. The findings suggest that sorgoleone acts as a signaling compound, facilitating plant–fungal interactions while maintaining a balance in resource allocation between the symbiotic partners. The study also highlighted the role of fungal hyphae in expanding the root surface area, effectively bypassing the P-depleted zones near plant roots and enhancing nutrient absorption.

Additionally, the research investigated the microbial dynamics of the rhizosphere and the genetic responses of sorghum to AMF inoculation and sorgoleone exposure. While bacterial and fungal communities in the rhizosphere remained largely unaffected by sorgoleone application, significant differences were observed in AMF diversity, suggesting a selective effect on fungal populations. The upregulation of genes involved in phosphate transport (SbPT8-SbPT11) and sorgoleone biosynthesis (CYP71AM1) further supports the hypothesis that sorgoleone promotes AMF colonization and symbiotic efficiency. The study reinforces the importance of root exudates in mediating plant–microbe interactions and suggests potential agricultural applications for optimizing P acquisition in crops through targeted modulation of AMF and signaling molecules like sorgoleone.

SorghumBase examples: 

SorghumBase examples:  Several sorghum genes showed increased expression in response to AMF and sorgoleone : Sb02g009880(SORBI_3002G116100), Sb06g002560(SORBI_3006G026900), Sb06g002540(SORBI_3006G026800), Sb03g029970(SORBI_3003G243400)

Figure 1: The authors highlight genes linked to phosphate transport induced by mycorrhizal symbiosis. In sorghum (Sorghum bicolor), phosphate transport is facilitated by a family of genes known as phosphate transporters (PHTs), which play crucial roles in phosphorus uptake and distribution within the plant. The PHT1 family, in particular, is primarily responsible for phosphate uptake from the soil. Searching for for one of the genes SORBI_3006G026900 in Sorghumbase shows phylogenetic analysis of SORBI_3006G026900 under Homology panel reveals its evolutionary relationships with homologous genes across diverse plant species.This gene shows strong evolutionary ties within the Poaceae family, sharing orthologs with Zea mays (Zm00001eb7720) and Oryza sativa (Os04g0618800), indicating functional conservation among grass species. The closest annotated homolog in Oryza japonica (PT8) shares 52% identity, reinforcing its functional significance in phosphorus uptake. The alignment overview (right panel) presents protein sequence alignments color-coded by InterPro domains, highlighting conserved regions across homologs. The blue blocks represent highly conserved sequences, with PR020846 – MFS_dom (Major Facilitator Superfamily domain) being a key feature. This domain is present in 568 out of 614 genes (92.5%) within this gene tree, indicating its strong evolutionary conservation and likely functional significance in phosphate transport across diverse plant species.
Figure 2: The expression profile of Sb06g002560 (SORBI_3006G026900), as shown in the SorghumBase expression atlas, indicates low to moderate expression across different plant tissues. The gene is notably expressed in leaf, flag leaf, root, and inflorescence, suggesting its potential role in phosphate uptake and transport in these key tissues.

Reference:

Figueiredo de Oliveira I, Ferreira Simeone ML, Gomes de Paula Lana U, de Carvalho Guimarães C, Morais de Sousa Tinôco S. Enhancing Sorghum Growth: Influence of Arbuscular Mycorrhizal Fungi and Sorgoleone. Microorganisms. 2025 Feb 15;13(2):423. PMID: 40005789. doi: 10.3390/microorganisms13020423. Read more

Related Project Websites: 

Optimizing Sorghum–AMF Symbiosis: The Role of Sorgoleone in Enhancing Phosphorus Uptake and Plant Growth

Leave a Reply

Your email address will not be published. Required fields are marked *