On March 27, 2025, Chun-Peng Song's team from Henan University published a research paper entitled "Horizontally acquired CSP genes contribute to wheat adaptation and improvement" in Nature Plants.
This study reported for the first time that the CSP genes from the cold shock protein encoded by prokaryotes was horizontally transferred to the staple food crop wheat. These genes play a key role in enhancing crop drought resistance, suggesting its potential as a valuable genetic resource for optimizing crop environmental adaptability. Because these CSP genes have been integrated into the recipient genome and have undergone long-term positive selection, they provide important reference for modern transgenic engineering and synthetic biology technology to improve modern crops.
Wheat (Triticum aestivum L.) is one of the most important food crops in the world, providing about 20% of dietary energy and protein for humans. As an allohexaploid crop (AABBDD, 2n = 6x = 42), the genome structure of common wheat is complex, including three subgenomes, A, B, and D, which are derived from three different diploid ancestors. Wheat originated in the Fertile Crescent of Central Asia and has shown stronger adaptability and wider global distribution than its diploid ancestors. However, there is still a lack of systematic research on the genetic basis of the wide adaptability of hexaploid wheat, which limits the progress of stress-resistant breeding and variety improvement.
Horizontal gene transfer (HGT) is one of the important driving forces of biological evolution. HGT events are relatively common in lower organisms and are an important evolutionary pathway for them to quickly adapt to environmental changes and acquire new functions. However, the frequency of HGT is significantly reduced in higher plants, and there are few reports on the identification and functional research of HGT in staple crops that have attracted much attention.
Chun-Peng Song's team is mainly committed to using Aegilops tauschii to expand the genetic diversity and stress resistance improvement of modern wheat D subgenome. As a series of work derived from the research group's "Wheat D Genome Reconstruction Project", this study has three important components.
First, based on the high-quality reference genomes and corresponding network resources of four representative Ae. tauschii (DD), the "ancestor species" of the D subgenome of hexaploid wheat (AABBDD) completed by the research group in the early stage, a class of HGT genes from bacteria was discovered using the strategy of HGT gene analysis and identification. The protein sequence and structure encoded by this gene are highly similar to the CSP protein in bacteria, and only contains a CSD domain at the N-terminus, named CSP-Hs.
In-depth analysis found that the CSP-Hs gene only exists in members of the Triticeae, and the CSP-Hs in modern hexaploid wheat may originate from the genome polyploidization event.
Second, using molecular biology and genomics techniques, the nucleic acid unzipping activity of CSP-Hs protein was identified, and it can bind to the precursor mRNA of its regulatory gene to maintain its stability, thereby regulating a series of downstream target genes, including photosynthesis-related genes and abiotic stress response genes.
Further studies have found that CSP-H improves wheat's resistance to abiotic stress and photosynthetic efficiency by regulating the transcript abundance of these genes, promoting the spread of wheat from its origin to all parts of the world.
Figure 1. TaCSP-H1 is involved in abiotic stress responses of wheat. (Wang, et al., 2025)
Third, using the "Kaishan" series of introgression germplasm resources created by the research group, valuable stress resistance gene application pathways were developed.
In the existing resequencing data of the natural population of Ae. tauschii, the authors identified two haplotypes of CSP-H genes, AetHap1 and AetHap2, of which AetHap1 has stronger nucleic acid binding ability and abiotic stress resistance. By introducing the chromosome fragment of Ae. tauschii containing this haplotype into the modern wheat variety Zhoumai18 through the introgression method, the photosynthetic efficiency and single plant yield of Zhoumai18 can be significantly improved.
What is more interesting is that since the CSP-H gene only exists in species of the Triticeae, the authors introduced this gene into other staple crops and found that it can also increase the yield of rice under drought conditions, reflecting its excellent breeding value and application prospects.
This study not only deeply reveals the key role of HGT in crop adaptation and domestication, but also finds that the exogenous genes obtained through HGT have better genetic stability and environmental adaptability in crops, which not only provides valuable gene resources and new research ideas for future crop breeding and improvement, but also lays a solid biological foundation for the safety of foreign gene utilization.
Based on the important findings of this study, Nature Plants published a Research Briefing review article "Horizontal gene transfer of cold shock protein genes boosted wheat adaptation and expansion" in the same period, summarizing and commenting on the significance and application prospects of this research finding.
The article pointed out that although the HGT mechanism has evolutionary significance for plant adaptation to terrestrial environments, there has been no reliable case of bacterial HGT directly affecting crop traits in crop systems. This study has demonstrated in a groundbreaking way how genes derived from bacteria promote the geographical expansion of wheat through the HGT mechanism, and also demonstrated the biological function and importance of HGT events in the evolution of crops.
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