Researchers have identified two key genes, SbSLT1 and SbSLT2, that help sorghum resist Striga by preventing its germination.
Chinese scientists have identified two key genes that enable sorghum to resist Striga, a parasitic plant responsible for major crop losses. This discovery not only sheds light on sorghum’s natural defense mechanisms but also demonstrates how AI can predict critical amino acid sites in strigolactone (SL) transporters—insights that could enhance resistance to parasitic plants in various crops.
The study, published in Cell, was led by Prof. Qi Xie’s team at the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, in collaboration with five other institutions.
Striga, commonly known as “witchweed,” and other parasitic plants like Orobanche depend on host plants for nutrients and water, significantly reducing crop yields and disrupting agricultural ecosystems. Striga alone infests more than 50 million hectares of farmland across Africa, causing $1.5 billion in annual economic losses and impacting over 300 million people. In China, Striga is found in regions such as Guangdong and Yunnan, while Orobanche threatens crops like sunflowers and tomatoes in Inner Mongolia and Xinjiang.
How Striga Infects Sorghum
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-Powered Predictions and Cross-Species Implications
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.
The researchers emphasized that the discovery of SbSLT1 and SbSLT2 could provide crucial tools for combating parasitic plants, potentially addressing food security challenges in countries severely affected by parasitic plants, especially African and Asian countries, thereby contributing to regional peace and stability. Future research will focus on validating these genes in crops such as maize, tomato, and millet, with the goal of advancing the commercialization of Striga-resistant crops.
Reference: “Resistance to Striga parasitism through reduction of strigolactone exudation” by Jiayang Shi, Cuo Mei, Fengyong Ge, Qingliang Hu, Xinwei Ban, Ran Xia, Peiyong Xin, Shujing Cheng, Gaohua Zhang, Jiawei Nie, Shiqi Zhang, Xiaowei Ma, Yi Wang, Jinfang Chu, Yuhang Chen, Bing Wang, Weihua Wu, Jiayang Li, Qi Xie and Feifei Yu, 12 February 2025, Cell.
DOI: 10.1016/j.cell.2025.01.022
