Researchers at the Riken Center for Sustainable Resource Science in Japan have made significant strides in plant protection by engineering a protein that can identify and respond to a variety of pathogens. Their study, published in the journal Science, reveals how modifications to the Selective Cold Shock Protein (SCORE) can enhance plants’ immune responses against bacterial infections and other threats.
The SCORE receptor is adept at recognizing cold-shock proteins, which exist in over 85% of known bacteria, along with fungi and insects. By systematically swapping components of the SCORE protein, the team demonstrated that they could alter its recognition capabilities, potentially allowing plants to better defend themselves against infections. The study details these findings in a paper titled “Systematic discovery and engineering of synthetic immune receptors in plants.”
In their research, the scientists analyzed over 1,300 receptors derived from the genomes of 350 plant species. They emphasized that traditional plant immune receptors typically target specific pathogens but fail to protect against the vast array of pathogens that plants may encounter. While some studies have shown that immune receptors can be transferred between plant lineages to enhance defenses, the sheer number of possible receptor-microbe interactions complicates this process.
Led by Ken Shirasu, PhD, the plant immunity research group focused on efficiently identifying receptor-microbe pairs. Their efforts led to the discovery of an unknown immune receptor in the common citrus fruit, pomelo, which they named SCORE. Subsequent experiments revealed that SCORE specifically recognizes a segment of cold-shock proteins known as csp15.
By substituting certain amino acids within csp15, the researchers altered which cold-shock proteins SCORE could recognize. A comprehensive genome analysis indicated that most pathogens, excluding viruses, produce at least one variant of cold-shock protein. The research identified that while the majority of the 15 amino acids in csp15 are conserved across species, variations at positions 6, 7, 14, and 15 are significant and widespread.
Dr. Yasuhiro Kodata, a research scientist in Shirasu’s lab, noted, “The extensive natural variation in CSP recognition across SCORE orthologs from different plant lineages suggests that this kind of immune receptor has repeatedly evolved to fine-tune pathogen detection through specific amino acid substitutions.” This variation provides insight into how different plant lineages have adapted their immune responses over time.
Further analysis of diverse SCORE proteins highlighted specific amino acid locations that vary across lineages. By assessing the charge associated with these locations, the researchers can predict which csp15 types a specific SCORE may identify. They successfully engineered new SCORE variants based on the pomelo receptor, enabling recognition of additional pathogens. For instance, the naturally occurring pomelo SCORE was unable to identify cold-shock proteins from Ralstonia, Erwinia, or Xanthomonas species. However, through their innovative method, the scientists synthesized a new version of SCORE that can react to all these pathogens.
In the short term, this research offers a novel framework for identifying and engineering immune receptors from non-model plants, particularly long-lived species for which genetic tools are scarce. As a next step, the team aims to introduce these engineered SCORE variants into economically significant crops to evaluate whether these changes can enhance broad-spectrum resistance to pathogens and pests.
This breakthrough could pave the way for more resilient agricultural practices, providing farmers with the tools necessary to combat a wide range of plant diseases.
