Figure: Strigolactone Transporters SbSLT1 and SbSLT2 Mediate Striga Parasitism

Under the support of the National Natural Science Foundation of China (Grant Nos.: 32430077, 32222010, U1906204), a collaborative research team led by Prof. Qi Xie from the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, and the National Key Laboratory of Crop Germplasm Innovation and Molecular Breeding (Syngenta Group), Prof. Feifei Yu from China Agricultural University, and Prof. Jiayang Li from Yazhou Bay National Laboratory, has identified two strigolactone (SL) efflux transporters, SbSLT1 and SbSLT2, in sorghum for the first time. The study elucidates their role in conferring resistance to Striga parasitism. The findings, titled "Resistance to Striga Parasitism through Reduction of Strigolactone Exudation," were published online in Cell on February 12, 2025. Paper link: https://doi.org/10.1016/j.cell.2025.01.022.

Parasitic plants pose a severe threat to agricultural production and ecosystems, with Striga spp. (witchweed) and Orobanche spp. (broomrape) being the most destructive to crops. Striga primarily parasitizes monocot crops such as sorghum, maize, and millet, significantly limiting food production in Africa, Asia, and tropical regions. According to Science, Striga is listed as one of the seven major global crop diseases. The parasitic process of Striga is highly covert and difficult to control. Traditional methods, including chemical agents, crop rotation, and soil improvement, have limited efficacy. Therefore, breeding Striga -resistant crop varieties has become a critical solution.

The research team uncovered the physiological mechanisms underlying Striga germination and parasitism under phosphorus-deficient conditions. They found that phosphorus deficiency promotes SL exudation in sorghum. Using gene mining combined with big data analysis and molecular/cellular biology approaches, the team identified two key SL efflux transporter genes, SbSLT1 and SbSLT2. These genes play a crucial role in inducing Striga seed germination and growth. Knockout of these genes significantly reduced Striga seed germination rates. Field trials demonstrated that sorghum with knocked-out SbSLT1 and SbSLT2 genes exhibited a 67-94% reduction in parasitism rates and a 49-52% decrease in yield loss. This achievement provides essential genetic resources and technical support for breeding Striga -resistant sorghum varieties.

Further AI-based simulations predicted a conserved phenylalanine residue critical for SL transport, which exists in homologous proteins across major crops. The team confirmed that maize ZmSLT1/ZmSLT2 and tomato SL transporters share similar SL efflux functions, indicating the broad conservation of this mechanism. These findings offer a universal solution for combating parasitic plants in other crops. The study provides novel strategies and tools for breeding Striga -resistant crops, with significant theoretical and practical value. Moving forward, the team will validate the function of these genes in additional crops and advance the industrialization of Striga-resistant varieties.