Novel Protease Inhibitors Provide Disease Resistance in Potatoes

At a Glance

Researchers at Colorado State University have identified novel protease inhibitors from a wild potato species that provide disease resistance and may be used for anti-microbial applications in food production. Methods and compositions are proprietary.

Background

Potato is a major staple crop, and necrotrophic bacterial pathogens such as Pectobacterium sp. and Dickeya sp. are major threats to potato production and therefore, global food security. These diseases cause over $40 million in annual loss to the US potato industry alone. Most lines of cultivated potato (Solanum tuberosum) are susceptible to soft rot caused by these pathogens, however, certain lines of wild potato have been found to be resistant.

It is understood that soft rot bacteria such as Pectobacterium sp. have several known pathogenicity factors, including the production of cell wall degrading enzymes (cellulases, pectinases, proteases, etc.) that break open plant cells and ultimately enable the bacteria to establish and grow. However, specific resistance genes have yet to be discovered. In addition, there are currently no reliable chemistries available to prevent these diseases.

Overview

Using a multi-omic approach, protein extracts isolated from resistant stem and tuber tissues have been found to inhibit the ability for bacteria to produce cellulases, pectases, and proteases. Subsequent proteomic characterization of these extracts have indicated an abundance of protease inhibitors. Genomic analysis of resistant and non-resistant potato lines further support that the resistant variety encodes several protease inhibitor genes absent in non-resistant varieties, as well as coding sequence differences in the protease inhibitors that are common between the species. Taken together, these data support that the protein extract discovered here is not only novel, but also that the trait can be transferred into domestic potato varieties to provide resistance to soft rot pathogens.

Furthermore, these protease inhibitors can be isolated and manufactured for applications in food safety and agricultural production as anti-microbial compounds. Research is underway to determine the impact on human bacterial pathogens.

This novel protein extract inhibited bacterial protease activity, motility, and affected cell morphology, see Figure 1.

Recombinant protease inhibitors reduced Pectobacterium motility, protease activity, and disease symptoms, see Figure 2.