The Botrytis cinerea elicitor protein BcIEB1 interacts with the tobacco PR5‐family protein osmotin and protects the fungus against its antifungal activity

Abstract

The broad-range phytopathogenic fungus Botrytis cinerea secretes hundreds of proteins during infection of its plant hosts. One of these proteins, BcIEB1, is abundantly secreted and is able to elicit plant defenses, probably as a pathogen-associated molecular pattern, although its native function in B. cinerea biology remains unknown. Pull-down experiments designed to isolate the molecular target of BcIEB1 in tobacco resulted in the identification of osmotin, a pathogenesis-related protein of family 5 that shows antifungal activity. The expression of osmotin in Escherichia coli allowed the verification of the BcIEB1-osmotin interaction with pure proteins by pull-down and far Western blot experiments, as well as the confirmation of the activity of osmotin against B. cinerea. Interestingly, B. cinerea Δbcieb1 mutants are more susceptible than the wild-type to osmotin, and the external addition of pure BcIEB1 protects the Δbcieb1 mutants, as well as Saccharomyces cerevisiae, from the antifungal action of osmotin, thus pointing at PR5 inhibition as the primary native function of BcIEB1. The question of whether osmotin is also involved in the activation of plant defenses by BcIEB1 is also addressed, and the data suggest that osmotin does not participate in the elicitation process.

Protein elicitor PeaT1 enhanced resistance against aphid (Sitobion avenae) in wheat

“…Sitobion avenae , the dominant aphid of winter wheat in China, is able to transmit barley yellow dwarf virus, and directly affect the yield and quality of wheat by its feeding behavior . To meet increasing demands for food quality and safety, protein elicitors have attracted more attention as an alternative to chemical pesticide use . Elicitors are molecules that trigger a defense response in plants, including abiotic elicitors such as metal ions and inorganic chemicals, biotic elicitors from pathogens or herbivores, and chemicals that are accumulated or released at the attack site by the plant upon pathogen or herbivore attack or under abiotic stress .…”

“…21 To meet increasing demands for food quality and safety, protein elicitors have attracted more attention as an alternative to chemical pesticide use. [22][23][24] Elicitors are molecules that trigger a defense response in plants, including abiotic elicitors such as metal ions and inorganic chemicals, biotic elicitors from pathogens or herbivores, and chemicals that are accumulated or released at the attack site by the plant upon pathogen or herbivore attack or under abiotic stress. 25,26 Elicitors can be classified into two groups: general elicitors induce a defense response in host and non-host plants, and race-specific elicitors trigger a defense response in host plants only.…”

New tools for high‐throughput expression of fungal secretory proteins in Saccharomyces cerevisiae and Pichia pastoris

“…B), and the results were almost always identical for the three colonies, although the apparent molecular weights observed for the recombinant proteins did not match those expected (Table S1) in every case. In the case of BcIEB1, for example, several bands were obtained, all of them with higher‐than‐expected molecular weight, a phenomenon that has been observed previously for the expression of this same protein in P. pastoris and that was attributed to extensive glycosylation (González et al ., ). Size discrepancies were most obvious for BcXyn11A and BcXyn11C, with a difference of about 70 kDa between the observed and expected weights, and in the case of BcSUN1, for which various sizes were observed for the recombinant proteins, ~30 kDa for BcSUN1.6 and ~75 kDa for BcSUN1.73 and BcSUN1.77, while 49 kDa was expected.…”

“…In order to test the usefulness of the yeast expression systems reported here, several B. cinerea secretory proteins previously characterized by our group were selected (Table S1): BcSpl1 (Frías et al ., , ), BcIEB1 (Frías et al ., ; González et al ., ), BcSUN1 (Pérez‐Hernández et al ., ), and the xylanases BcXyn11A (Brito et al ., ; Noda et al ., ), BcXyn11B and BcXyn11C (García et al ., ). These six proteins had also been experimentally identified in various proteomic studies as components of the B. cinerea secretome (González et al ., ).…”

The elicitor protein BcIEB1 and the derived peptide ieb35 provide long‐term plant protection

“…Besides its elicitor activity, BcIEB1 has also been shown to interact, via the ieb35 peptide, with the tobacco protein osmotin (accession number P14170, encoded by the ap24 gene), a member of the pathogenesis‐related protein 5 (PR5) family (González et al , 2017). Osmotin is a ubiquitous protein that has been defined as “a plant sentinel” because of its participation in multiple abiotic and biotic stress responses in plants (Anil Kumar et al , 2015).…”