Sorghum, a high-biomass crop, shows promise for phytoremediation of cadmium (Cd)-contaminated soils, with Cd uptake and translocation largely influenced by genotype-specific expression of ABC transporter proteins, particularly SbABCB11.

Keywords: AsODN, Cadmium efflux, Candidate gene-based association, Haplotype analysis, Sorghum, Xylem loading

Cadmium (Cd) contamination presents a major environmental and health challenge, with approximately 20 million hectares of land in China polluted by heavy metals. Phytoremediation, a sustainable and cost-effective solution, leverages plants to extract contaminants from the soil. Sorghum (Sorghum bicolor L. Moench), a high-biomass C4 crop, has emerged as a promising candidate due to its resilience to Cd stress and ability to thrive on marginal lands. Studies have demonstrated genotype-specific variations in Cd uptake and translocation, with sweet sorghum genotypes like ‘Keller’ and ‘1794’ exhibiting notable Cd removal capacities. Sorghum’s capacity to utilize municipal sewage sludge further enhances its biomass yield while mitigating waste pollution. However, the precise mechanisms governing Cd absorption and translocation in sorghum remain insufficiently understood.

Recent research by scientists from Chinese Academy of Sciences, China National Botanical Garden and the University of Chinese Academy of Sciences have identified the ATP-binding cassette (ABC) transporter family as pivotal in Cd transport. Among these, the SbABCB11 gene plays a significant role in enhancing Cd translocation from roots to shoots. Segmental duplication primarily drives the evolution of the ABC gene family in sorghum, with the ABCG, ABCB, and ABCC subfamilies implicated in Cd transport. Notably, SbABCB11 was shown to facilitate Cd efflux into the xylem, contributing to efficient root-to-shoot translocation. Experimental suppression of SbABCB11 using antisense oligonucleotides (asODN) significantly reduced Cd accumulation in sorghum shoots, confirming its function in Cd transport. Further research into the structural variations and regulatory mechanisms of SbABCB11 and related genes can enhance phytoremediation strategies, potentially improving the effectiveness of sorghum in restoring Cd-contaminated soils.

SorghumBase examples: 

Figure 1: The Germplasm Tab for the sorghum ABC transporter Sobic.003G267700 shows the available protein-truncating variants (PTVs) that result in predicted loss of function for the gene. Sobic.003G267700 was identified by the authors to harbor 5 SNPs that were associated with Cd translocation capacity.
Figure 2: A neighborhood view of Sobic.003G267700 showing surrounding gene model conservation of other sorghum accessions. Notably, there are a some accessions where upstream gene models seem to indicate translocations or other structural differences that could possibly influence evolution or gene expression.

Reference:

Zhang B, Jia W, Lin K, Lv S, Guo Z, Xie W, He Y, Li Y. Integrative analysis of the ABC gene family in sorghum revealed SbABCB11 participating in translocation of cadmium from roots to shoots. Planta. 2025 Feb 20;261(3):62. PMID: 39979492. doi: 10.1007/s00425-025-04644-x. Read more

Genotypic Variation in ABC Transporters Influences Cadmium Phytoremediation Potential of Sorghum

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