On February 12, 2025, a collaborative study led by Professor Xie Qi’s research group from the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences / National Key Laboratory of Maize and Crop Germplasm Innovation & Molecular Breeding, Professor Feifei Yu’s team from China Agricultural University, and Academician Li Jiayang’s research team from the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences / Yazhou Bay National Laboratory, was published online in CELL under the title: “Resistance to Striga Parasitism through Reduction of Strigolactone Exudation”.
During the research process, JIUPO plant growth chambers were utilized for breeding and incubation experiments. The study is the first to reveal how phosphate-deficient environments stimulate the exudation of strigolactones (SLs) in crops and to elucidate the underlying molecular mechanisms. This work fills a critical knowledge gap in the field of regulating SL exudation to control parasitism by Striga species (witchweed).
Journal:
CELL
Impact Factor: 45.5
To investigate the physiological processes by which phosphate deficiency induces Striga parasitism in sorghum, the research team established a phosphate-deficiency simulation system using hydroponically grown sorghum. They found that under phosphate-starved conditions, SL levels in both sorghum roots and the hydroponic solution significantly increased. Through integrated transcriptomic analysis of sorghum roots treated with phosphate deficiency and exogenous SL (GR245DS), they identified two candidate ABC transporter genes, SbSLT1 and SbSLT2, responsible for SL export from sorghum roots.
Further experiments, including expression pattern analyses and in situ hybridization, demonstrated that SbSLT1 and SbSLT2 are predominantly expressed in the epidermal cells of sorghum roots, consistent with their proposed role in SL exudation into the rhizosphere.
Figure 1:Identification of two putative SL transporters, SbABCG36 and SbABCG48, in sorghum
Using heterologous expression systems in yeast, Xenopus oocytes, and Arabidopsis, the team confirmed that both SbSLT1 and SbSLT2 exhibit robust SL transport activity. Interestingly, homologous proteins SbSLT1-LIKE and SbSLT2-LIKE lacked SL transport capacity, underscoring the functional specificity of SbSLT1 and SbSLT2 within the sorghum ABCG transporter family.
To further elucidate the molecular basis of SL transport by these proteins, AlphaFold2 modeling combined with HOLE analysis was employed to predict SL transport channels in the membrane structure of SbSLT1 and SbSLT2. Experimental validation identified F693 in SbSLT1 and F642 in SbSLT2 as critical amino acid residues essential for SL transport activity. Notably, these conserved phenylalanine residues are absent in SbSLT1-LIKE and SbSLT2-LIKE, explaining their lack of transport function.
Sequence alignments revealed that homologs of SbSLT1 and SbSLT2 in monocotyledonous plants, as well as known dicotyledonous SL transporters, share these conserved residues, suggesting a potentially conserved SL export mechanism across monocots and dicots.
Figure 2: SbABCG36 and SbABCG48 as SL exporters
To functionally validate these findings, the team generated SbSLT1 and SbSLT2 knockout sorghum lines. Root exudates from these mutants contained significantly lower SL levels compared to wild-type plants. Additionally, Striga seed germination assays using these root exudates revealed a marked reduction in germination rates.
Field trials further demonstrated that SbSLT1 and SbSLT2 knockout lines exhibited a 67%-94% reduction in Striga parasitism and a 49%-52% decrease in yield losses compared to control lines.
These results highlight the significant potential of SbSLT1 and SbSLT2 genes in enhancing crop resistance to parasitic plants and mitigating agricultural yield losses caused by parasitism. This research provides a novel strategy for combating parasitic weeds such as Striga in economically important crops like sorghum and maize, holding substantial implications for global food security and economic sustainability.