natural-products-in-plant-pest-management

Proteinaceous and Polyketide Compounds in Plant Protection 121also be enhanced upon pathogen attack both in compatible and incompatibleplant–pathogen combinations. Alien CSPs are recognized by plants as componentsof PAMP and elicit resistance to some pathogens. Thus, CSPs fromMicrococcus lysodeikticus non-specifically induced defence responses inplants. It was found that a peptide consisting of 15 amino acid residues(csp15) that represented a consensus sequence of RNA-binding PNP-1 andRNP-2 motifs was responsible for eliciting activity towards some Solanaceaeplants (Felix and Boller, 2003). The peptide csp15 induced an ‘oxidative burst’in tobacco (Nicotiana tabacum, cv. Havanna 425) and potato (Solanumtuberosum), but was ineffective towards rice and cucumber cells.CspD from B. thuringiensis has been reported to induce resistance both inmonocotyledonous and dicotyledonous crops against a wide range of pathogens:from filamentous microorganisms (fungi and oomycetes) to viruses(Dzhavakhiya et al., 2000). For instance, CspD applied by dropping ontowheat leaves or by spraying potato and rice seedlings with water- or bovineserum albumin (BSA)-stabilized CspD solutions produced resistance againstS. nodorum, P. infestans and M. grisea, respectively. Effective crop protectionwas observed in both greenhouse and field experiments. Exposure of tobaccoplants to CspD induced resistance to tobacco mosaic virus (TMV) and potatoX-virus. Peptide csp15 of CspD protein (VKWFNAEKGFGFITP) also showedresistance-inducing activity on plants and in model plant–pathogen systems.Treatments of tobacco leaf halves with 1–10 μmol csp15 in 0.1% BSA a daybefore inoculation with TMV resulted in a drastic reduction of lesion spotnumber on the treated halves as compared to 0.1% BSA-treated (control)halves or whole control leaves of the same plant (Kromina and Dzhavakhiya,2004).Several tests were carried out to identify which host defence responses tothe pathogen challenge are activated by CspD and csp15. Applying csp15 tothe surface of discs cut from potato tubers (cv. Istrinskiy, R1) increased thehypersensitive response of potato cells to the incompatible P. infestans race r4with a decreased number of dead cells and induced accumulation of salicylicacid in the tuber tissues. Both CspD and csp15 have no fungitoxicity. Additionof the peptide to the suspension of cultured tobacco cells activated theH + pump and caused a reversible change in the extracellular pH. The resistanceinduced with csp15 or CspD in plants has a systemic character (Krominaand Dzhavakhiya, 2004).To transfer the CspD gene into tobacco plants, the pBilt7 plasmid, containingthe CspD expression cassette (P35S/CspD/pACaMV), on pBin19 vectorbackground was constructed and transformed into A. tumefaciens. As a result,seven lines of cv. Xanthi (NN) and five lines of cv. Samsung (nn) were produced.Expression of CspD in these lines was confirmed by real-time PCR.The transgenic tobacco plants had the same habitus as control plants andproduced fertile projeny. The transgenic lines showed increased resistance toAlternaria longipes and TMV that coincided with the range of antipathogenicactivity observed for the elicitor protein per se. Importantly, the level of CspDexpression coincided with the resistance level to the both pathogens amongall tested lines as well as inside any one line. These findings lead to the