Unfoldome variation upon plant‑pathogen interactions: strawberry infection by Colletotrichum acutatum

Intrinsically disordered proteins (IDPs) are proteins that lack secondary and/or tertiary structure under physiological conditions. These proteins are very abun- dant in eukaryotic proteomes and play crucial roles in all molecular mechanisms underlying the response to envi- ronmental challenges. In plants, different IDPs involved in stress response have been identified and characterized. Nevertheless, a comprehensive evaluation of protein dis- order in plant proteomes under abiotic or biotic stresses is not available so far. In the present work the transcriptome dataset of strawberry (Fragaria x ananassa) fruits interact- ing with the fungal pathogen Colletotrichum acutatum was actualized onto the woodland strawberry (Fragaria vesca) genome. The obtained cDNA sequences were translated into protein sequences, which were subsequently subjected to disorder analysis. The results, providing the first estima- tion of disorder abundance associated to plant infection, showed that the proteome activated in the strawberry red fruit during the active fungal propagation is remarkably depleted in disorder. On the other hand, in the resistant Electronic supplementary material The online version of this article (doi:10.1007/s11103-015-0353-7) contains supplementary material, which is available to authorized users. * Barbara Zambelli barbara.zambelli@unibo.it 1 Department of Agricultural Sciences, University of Bologna, Bologna, Italy 2 Research and Innovation Centre, Foundation Edmund Mach (FEM), San Michele all’ Adige, Trento, Italy 3 Department of Biomedical Sciences, University of Padova, Padua, Italy 4 Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy white fruit, no significant disorder reduction is observed in the proteins expressed in response to fungal infection. Four representative proteins, FvSMP, FvPRKRIP, FvPCD-4 and FvFAM32A-like, predicted as mainly disordered and never experimentally characterized before, were isolated, and the absence of structure was validated at the secondary and tertiary level using circular dichroism and differential scanning fluorimetry. Their quaternary structure was also established using light scattering. The results are discussed considering the role of protein disorder in plant defense.