Comparison of cerato-platanin family protein BcSpl1 produced in Pichia pastoris and Escherichia coli

- We have successfully expressed BcSpl1 in Escherichia coli.
- eBcSpl1 remains the same elicitor activities to hosts as BcSpl1.
- eBcSpl1 exhibited chitin-binding properties.
- The high-yield expression of eBcSpl1 gives a reference for other CP proteins.
- eBcSpl1 contributes to future large-scale applications for crop protection.

The Botrytis cinerea BcSpl1 protein is a member of the cerato-platanin family, and consists of 137 amino acids and two disulfide bridges. This protein induces the onset of necrosis in infiltrated plant hosts. Recombinant BcSpl1 proteins produced in Pichia pastoris (pBcSpl1) and Escherichia coli (eBcSpl1) were initially compared regarding their abilities to induce necrosis and systemic acquired resistance (SAR). The pBcSpl1 and eBcSpl1 treatments led to the development of necrotic lesions on tomato leaves, and provided tomato plants with SAR to B. cinerea. The lesion area of leaves infiltrated with the BcSpl1 proteins decreased by 22.7% (pBcSpl1) and 21.8% (eBcSpl1). Additionally, eBcSpl1 up-regulated the expression levels of some defense-related genes, including PR-1a, prosystemin, PI I, and PI II, as well as SIPK and TPK1b, which encode two protein kinases. Furthermore, eBcSpl1 exhibited chitin-binding properties. Our data revealed that the E. coli expression system produces higher BcSpl1 yields than the P. pastoris system. This high-yield expression of BcSpl1 may be relevant for future large-scale applications of this elicitor to improve crop production.