AtLEC2‐Mediated Enhancement of Endoplasmic Reticulum‐Targeted Foreign Protein Synthesis in <i>Nicotiana benthamiana</i> Leaves: Insights From Transcriptomic Analysis

Many proteins used in industrial and pharmaceutical applications are typically synthesized within the secretory pathway. While yeast and mammalian cells have been engineered to enhance the production of endomembrane-targeted proteins, similar strategies in plant cells remain underexplored. This study investigates the potential of arabidopsis leafy cotyledon 2 (AtLEC2), a key regulator of seed development, to enhance the production of proteins targeted to the endoplasmic reticulum (ER) in Nicotiana benthamiana leaves. Through transient expression experiments, we demonstrate that AtLEC2 selectively increases the production of ER-targeted GUS without affecting its cytosolic variant. Moreover, leaves agroinfiltrated with AtLEC2 show a significant increase in ER-GFP accumulation compared to controls lacking AtLEC2. Transcriptomic analysis reveals that AtLEC2 promotes ribosome and chloroplast biogenesis, along with the upregulation of genes involved in photosynthesis, translation, and membrane synthesis. Notably, seed-specific poly(A) binding proteins involved in RNA stability and translation initiation, as well as 3-hydroxy-3-methylglutaryl coenzyme A reductase-linked to ER hypertrophy-are highly upregulated. This study establishes a novel connection between AtLEC2 and the enhancement of ER-targeted foreign protein synthesis, paving the way for innovative strategies in plant cellular engineering.