Work

Strigolactone effects on Sorghum bicolor ecophysiology and symbioses

Year: 2026

Type: article

Abstract: Strigolactones are ecologically, developmentally, and physiologically important hormones, yet much remains unknown about their evolution and functions in non-model species. Sorghum, a globally important C4 cereal, exhibits natural variation in root-exuded strigolactones. Differences in sorghum strigolactone stereochemistry are associated with resistance to parasitic plants but with evidence for potential trade-offs. We studied sorghum mutants of the strigolactone biosynthetic genes, CAROTENOID CLEAVAGE DIOXYGENASE 8 (SbCCD8b) and LOW GERMINATION STIMULANT 1 (LGS1), both previously shown to be Striga resistant by stimulating little germination of the parasite. CRISPR-Cas9 deletions of SbCCD8b changed the accumulation of low abundance metabolites, reduced net carbon assimilation rate, altered root architecture and anatomy, and diminished the establishment and benefit of mycorrhizal symbionts. For LGS1 CRISPR-Cas9 deletions, differentially expressed genes were enriched with promoter motifs that regulate stress response and growth pathways, net carbon assimilation rate was reduced, and the colonization of mycorrhizal symbionts was delayed. We additionally restored functional LGS1 into the RTx430 genetic background, which normally has the lgs1-2 natural deletion allele. While root exudates from LGS1 insertion mutants rescued Striga susceptibility, we did not see consistent rescue of other traits altered in LGS1 deletion mutants. We hypothesize that epistasis with a neighboring strigolactone synthesis gene, which is rarely lost without concomitant loss of LGS1, may alter the phenotypic effects of LGS1 variation. These findings provide context for potential trade-offs associated with host resistance to parasitic plants and further define the roles of strigolactones in shaping sorghum physiology growth, and development.

Source: PLANT PHYSIOLOGY

DOI: 10.1093/plphys/kiag549