Engineering Macromolecular Trafficking Into the Citrus Vasculature

Area of Science:

• Plant Biology
• Molecular Biology
• Biochemistry

Background:

• Plant vasculature facilitates long-distance transport of nutrients and signaling molecules.
• Angiosperm sieve elements lack nuclei, relying on companion cells for RNA and protein synthesis for systemic signaling.
• Phloem translocation involves ribonucleoprotein complexes, with phloem protein CmPP16 facilitating RNA and protein movement in Cucurbitaceae.

Purpose of the Study:

• To characterize the Citrus CsPP16 protein's potential for associating with mobile proteins and its vascular enrichment.
• To evaluate CsPP16's capacity to confer phloem mobility to antimicrobial peptides (AMPs) for innate immunity.
• To demonstrate engineering macromolecular trafficking in plant vasculature for long-distance transport.

Main Methods:

• In silico characterization of Citrus CsPP16.
• Engineering translational fusions of AMPs with CsPP16.
• Assessing phloem mobility of engineered AMPs.

Main Results:

• CsPP16 exhibits potential for protein association and vascular enrichment.
• Engineered AMPs fused to CsPP16 were successfully mobilized into the phloem for long-distance transport.
• Translocated AMPs showed potential to mitigate the growth of *Candidatus* Liberibacter asiaticus.

Conclusions:

• CsPP16 can facilitate phloem translocation of fused peptides, demonstrating engineered macromolecular trafficking.
• This system has implications for crop defense by enabling targeted delivery of AMPs to combat pathogens like *Candidatus* Liberibacter asiaticus.
• The engineered vascular trafficking system offers possibilities for modulating plant traits such as growth, defense, and productivity.