Figure 3.

Analysis of the effect of Fcα‐fusion on expression and activity. Necrosis is induced in Nicotiana benthamiana leaves upon expression of SP‐TGF‐β1 and SP‐TGF‐β1‐KDEL, but not when fused to LAP or Fcα. (a) Leaf necrosis on 5 days postinfiltration of several TGF‐β1 constructs. (b) Yield of SP‐TGF‐β1 and Fcα‐TGF‐β1 in crude extracts at 2–5 dpi as determined by ELISA (n = 3, error bars indicate standard error). Significant differences as determined by a Welch's t‐test (P < 0.05) between samples are indicated with an asterisk. (c) Biological activity of Fcα‐TGF‐β1 was determined by using MLEC cells containing a TGF‐β1‐inducible luciferase reporter construct. Cells were treated with recombinant TGF‐β1 (rTGF‐β1 from mammalian cells) or plant‐produced Fcα‐TGF‐β1 (from dpi 3), and luciferase expression was measured after overnight incubation.