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Lettuce: The Workhorse of Chloroplast
Engineering

Among the growing toolkit of plant hosts for biologic
expression, lettuce (Lactuca sativa) stands apart as the
most mature, scalable, and clinically validated platform for
edible therapeutics. It isn’t just a convenient leafy green—
it’s a biologic manufacturing engine, optimized by both
nature and design for oral drug delivery.

Over the past decade, lettuce has become the preferred
system for chloroplast-based protein expression, where
therapeutic genes are inserted directly into the chloroplast
genome rather than the nuclear genome. This strategy
offers unique benefits that are now proving critical for
therapeutic protein yield, safety, and downstream delivery.

Let’s explore why lettuce has become the backbone of
early edible biologic programs.

1. High-Yield Expression Through Chloroplast
Amplification

Each lettuce cell contains up to 100 chloroplasts, and each
chloroplast houses dozens of genome copies. This creates
a natural amplification system: when a therapeutic gene is
inserted into the chloroplast genome, it is replicated across
thousands of genome copies per cell, enabling
extraordinarily high protein yields—often up to 70% of
total leaf protein content.

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