Scientists Engineer SCORE Protein for Enhanced Plant Defense Against Pathogens

Researchers at the Riken Center for Sustainable Resource Science in Japan have made a significant breakthrough in plant pathology. They have identified a versatile protein, known as the Selective Cold Shock Protein (SCORE), which can be engineered to provide plants with enhanced protection against a variety of pathogens, including bacteria and fungi. This discovery, detailed in a recent paper published in the journal Science, presents a promising avenue for developing resilient crops.

The SCORE receptor is capable of detecting cold-shock proteins, which are found in over 85% of all known bacteria, as well as in fungi and insects. By systematically swapping sections of the SCORE protein, the researchers demonstrated that it is possible to alter the types of cold-shock proteins it recognizes. This adaptability paves the way for engineering SCORE to equip plants with defenses tailored to combat specific infections.

Revolutionizing Plant Immunity

The research team, led by Ken Shirasu, PhD, and including co-author Yasuhiro Kodata, PhD, focused on characterizing over 1,300 receptors from the genomes of 350 plant species. Traditionally, plant receptor proteins trigger immune responses against pathogens, but no single receptor can address all existing and emerging threats. The complexity of potential receptor-microbe interactions adds to this challenge.

In their study, the scientists discovered an unknown immune receptor in the common citrus fruit, pomelo, which they named SCORE. Through a series of experiments, they found that SCORE responds specifically to a subset of cold-shock proteins, particularly a segment known as csp15. By altering certain amino acids in csp15, the researchers could change which cold-shock proteins SCORE recognized.

Further analysis uncovered that most pathogens, with the exception of viruses, produce at least one type of cold-shock protein. The researchers noted that while many of the 15 amino acids in csp15 are conserved across different species, there is considerable variability at positions 6, 7, 14, and 15. This finding suggests that immune receptors are capable of evolving to refine pathogen detection through specific amino acid changes.

Engineering New Defense Mechanisms

The study also revealed extensive natural variation in SCORE across different plant lineages. This variation allows scientists to predict which csp15 variants a given SCORE can recognize based on the charge of specific amino acid locations. Leveraging this knowledge, the team engineered new versions of the SCORE receptor to target different pathogens by substituting sections of the amino acid sequence with alternatives.

For instance, the natural SCORE found in pomelo does not recognize cold-shock proteins from Ralstonia, Erwinia, or Xanthomonas species of bacteria. However, using their innovative approach, the researchers successfully synthesized a new version of SCORE that can respond to all three pathogens.

“This study provides a new framework for identifying and engineering immune receptors from non-model plants, particularly long-lived perennials for which genetic tools are limited,” stated Dr. Shirasu. Looking ahead, the researchers aim to introduce these engineered SCORE variants into economically important crops to evaluate their effectiveness in enhancing broad-spectrum resistance to various pathogens and pests.

The implications of this research extend beyond the laboratory, potentially transforming agricultural practices and improving food security worldwide. By equipping plants with advanced defense mechanisms, scientists hope to mitigate the impact of diseases that threaten crop yields and, consequently, global food supplies.