Sorghum is one of the plants susceptible to Striga infestation. Sorghum roots release SLs, a class of plant hormones that help recruit mycorrhizal fungi for nutrient uptake. Unfortunately, Striga seeds dormant in the soil detect these SL signals, which trigger Striga germination and subsequent infestation of the host plant.
In this study, the researchers analyzed transcriptome data from sorghum roots under phosphorus-deficient conditions and strigolactone (SL) treatment separately.
The scientists identified two ABCG family SL transporter genes: Sorghum bicolor SL transporter 1 (SbSLT1) and Sorghum bicolor SL transporter 2 (SbSLT2). They determined that the SbSLT1 and SbSLT2 proteins control the efflux of SLs and knocking out the associated genes inhibits SL secretion. Under these conditions, Striga is unable to germinate and infect the host.
AI-based predictions further identified a conserved phenylalanine residue critical for SL transport. This residue is found not only in sorghum, but also in SL transporters across other monocot crops like maize, rice, and millet, as well as dicotyl crops such as sunflowers and tomatoes, suggesting a conserved mechanism across species.
Molecular biology and cellular biology experiments demonstrate the key function of this residue.
Field trials conducted in Striga-prone areas showed that sorghum with knocked-out SbSLT1 and SbSLT2 genes exhibited 67–94% lower infestation rates and 49–52% less yield loss. These findings offer valuable genetic resources and technical support for breeding Striga-resistant sorghum varieties.
Source : phys.org