What if milk’s most important proteins could be produced by plants instead of cows? A new study from Hebrew University researchers pushes plant-based “molecular farming” closer to that goal by showing that Arabidopsis seeds can manufacture bovine β-casein, one of the key proteins responsible for milk’s nutritional value and cheese-making properties.

The central challenge has been not just expressing a foreign animal protein in crops, but getting it to accumulate in the right cellular place where it remains stable and functional. The team engineered β-casein to include a targeting module derived from oleosin, a plant oil-body protein that naturally anchors to tiny lipid droplets in seed cells.

To find the best intracellular “address,” the researchers tested multiple compartment-targeting designs, expecting the protein to build up in vacuoles—typical storage sites for macromolecules. However, advanced electron microscopy revealed an outcome that contradicted the design logic: β-casein formed previously unrecognized protein-rich structures rather than localizing to the intended vacuolar compartment.

These structures resemble casein micelles and were closely associated with the seed’s smallest oil bodies. In other words, the plant appeared to reroute the engineered protein into a robust cytoplasmic storage-like aggregate that combines protein and lipids.

Crucially, this unexpected accumulation did not come at a biological cost. Seeds maintained healthy germination, suggesting the altered intracellular compartmentalization is compatible with normal seed function.

Performance measurements showed that the best plants produced β-casein at about 1.26% of total soluble seed protein—an amount that compares favorably with many earlier attempts at casein expression in plants. The results imply that the cell’s internal environment can actively foster efficient assembly of complex dairy proteins.

Beyond dairy alternatives, the work offers a blueprint for improving future recombinant protein crops. If plants can spontaneously generate resilient storage structures for otherwise difficult proteins, scientists may be able to streamline design strategies and reduce purification burdens.

The researchers have also extended the approach beyond the model organism, transforming safflower—an oil-seed plant valued for cultivation in hot climates and arid regions—bringing the technology toward crop-relevant production systems.

Subject of Research:
Not available

Article Title:
Subcellular localization of C-term-oleosin fused to β-casein reveals unexpected cytoplasmic accumulation in vacuole-targeted arabidopsis seeds

News Publication Date:
30-Jun-2026

Web References:
http://dx.doi.org/10.3389/fpls.2026.1872014

References:
Frontiers in Plant Science

Image Credits:
Almog Ozeri

Keywords:
plant molecular farming, β-casein, oleosin, oil bodies, Arabidopsis seeds, casein micelles, recombinant proteins, subcellular localization, sustainable dairy, cell biology

Tags: Arabidopsis seed engineeringbovine β-casein expression in cropsintracellular protein targeting in plantslipid droplet association in seed cellsmolecular farming in plantsplant biotechnology for dairy alternativesplant oil-body proteinsplant-based dairy protein productionplant-derived milk proteinsprotein accumulation in plant tissuesseed storage structures for recombinant proteinsunexpected protein structures in plant cells