Not Only Systemin: Prosystemin Harbors Other Active Regions Able to Protect Tomato Plants

Abstract

Prosystemin is a 200-amino acid precursor expressed in Solanaceae plants which releases at the C-terminal part a peptidic hormone called Systemin in response to wounding and herbivore attack. We recently showed that Prosystemin is not only a mere scaffold of Systemin but, even when deprived of Systemin, is biologically active. These results, combined with recent discoveries that Prosystemin is an intrinsically disordered protein containing disordered regions within its sequence, prompted us to investigate the N-terminal portions of the precursor, which contribute to the greatest disorder within the sequence. To this aim, PS1-70 and PS1-120 were designed, produced, and structurally and functionally characterized. Both the fragments, which maintained their intrinsic disorder, were able to induce defense-related genes and to protect tomato plants against Botrytis cinerea and Spodoptera littoralis larvae. Intriguingly, the biological activity of each of the two N-terminal fragments and of Systemin is similar but not quite the same and does not show any toxicity on experimental non-targets considered. These regions account for different anti-stress activities conferred to tomato plants by their overexpression. The two N-terminal fragments identified in this study may represent new promising tools for sustainable crop protection.

Protein Disorder in Plant Stress Adaptation: From Late Embryogenesis Abundant to Other Intrinsically Disordered Proteins

“…Protein disorder has a versatile contribution to both the plant immune system and pathogen virulence [190,191]. The N-terminal IDR of prosystemin, the 200-aa precursor of the peptidic hormone systemin responding to wounding and herbivore attack, was able to induce defence-related genes and protect tomato plants against Botrytis cinerea and Spodoptera littoralis larvae [192]. In the plant defence response, RPM1-INTERACTING PRO-TEIN 4 (RIN4) is a negative regulator and targeted by multiple bacteria effectors [193][194][195].…”

Prosystemin N-terminal protein fragments mitigate salt stress damages in tomato plants

“…For long time Sys was considered the unique biologically active sequence of ProSys. However, we previously identi ed in the N-terminal region of the precursor, two protein fragments, PS1-70 and PS1-120, able to induce defense-related genes and to protect tomato plants against Botrytis cinerea and Spodoptera littoralis larvae when exogenously applied (Molisso et al, 2022). Further bioinformatic and computational analyses recently conducted on the same part of ProSys structure Castaldi et al, 2024) highlighted the presence of shorter repeated protein stretches among which a peptide, indicated as G, additional protein displayed a robust biological activity (Castaldi et al, 2024).…”