Fig. 1.

Four phenomena to avoid to improve transient protein expression. Transient expression by infiltrating leaves of Nicotiana benthamiana with Agrobacterium tumefaciens is mediated by the transfer DNA (T‐DNA) that is injected by the bacterium into the plant cell through the type‐IV secretion system. Transient expression can be improved by avoiding immune responses; avoiding transcript degradation (silencing); avoiding endoplasmic reticulum (ER) stress caused by protein accumulation in the endoplasmic reticulum; and by avoiding protein degradation by plant proteases.