EAGER: Enhancing plant immunity and growth with cell-penetrating peptides for organic agriculture

To feed the growing world population, the agricultural sector needs to increase food production even while being attentive to the impact of new strategies on ecosystems and human health. Although fertilizers and pesticides play a crucial role in modern agriculture, their adverse impact on the environment and animal/human health have recently inspired a rapid rise in sustainable crop production.

A promising environment-friendly alternative is the use of biologics. However, many of the plant defense activators, biostimulants, and biopesticides currently used in sustainable agriculture are proteins and peptides that have low entry efficiency into plant cells, thus necessitating the use of high concentrations and consequently high costs. To address this limitation, this project will leverage a powerful membrane translocation domain (MTD) technology to improve the delivery of biological agents.

HrpZ, a proven defense activator, will be fused to MTD4, one of the most potent MTDs in hand, and tested in tomato for its efficacy in eliciting immune responses to bacterial and fungal pathogens. This approach should decrease the effective concentration of defense activators and thereby increase the economic viability of plant biologics for sustainable agriculture and farmers’ income.

In addition, the team will explore outreach activities to demonstrate how biodefense molecules can help plants ward off pathogens.

Although cell-penetrating peptides (CPPs) have been widely explored for delivering therapeutic agents to treat human diseases/conditions, their applications in plants have been more limited. The goal of this project is to examine the utility of a newly discovered class of CPPs, MTDs, to efficiently deliver HrpZ, a known biodefense activator/biostimulant, into crop plants to protect them from pathogen infection and insect infestation.

The three specific aims of this project are: [1] improve the efficiency of cellular entry and metabolic stability of MTD4; [2] determine the effects of MTD4-HrpZ and MTD4-N21 on tomato and rice defense, growth, yield, and drought tolerance; and [3] optimize and develop low-cost recombinant protein expression and chromatography-free purification strategies for large-scale field applications. After completion of the three objectives, this project will provide insights into how CPPs enter plant cells and how their different cellular structures (e.g., lipid composition in membranes) affect the cellular entry mechanism and efficiency of CPPs.

Importantly, the use of CPPs to promote plant immunity is likely to be transformative for plant disease control in sustainable agriculture. Our new strategies for overexpression and chromatography-free purification of recombinant proteins are also likely to be of broad interest. In addition, identification of powerful CPPs that can efficiently deliver peptides/proteins into plant cells will provide new tools for biological studies that seek to uncover in planta interactions between different proteins, including pathogen effectors.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.