Alpha Cinnamomin Elicits a Defence Response Against Phytophthora Cinnamomi in Castanea Sativa

Abstract

Phytophthora cinnamomi and P. cambivora are considered as the causal agents of Castanea sativa ink disease. These soil-borne plant pathogens invade and destroy the root system leading to the death of the trees.Most Phytophthora species secrete elicitins, a group of unique highly conserved proteins that are able to enhance plant defence responses in a systemic acquired resistance manner against infection by several pathogens. A cluster of four elicitin genes was identified in P. cinnamomi. In previous works one of these elicitins, α-cinnamomin was shown to restrict the invasion of root cortical tissues by P. cinnamomi preventing vascular colonization in cork and holm oak. In the present work, roots of chestnut plantlets grown in vitro were allowed to absorb α-cinnamomin at 100 µg/ml for two days before being inoculated with P. cinnamomi. The effects of this elicitin on host-pathogen interaction were studied at histological and ultrastructural levels.P. cinnamomi was restricted to the outer cortex of 65% of the roots pre-treated with α-cinnamomin. In these roots, the vascular cylinders were free of pathogen. On the contrary, the pathogen reached the vascular cylinder, penetrating the phloem and xylem vessels in all non-treated assayed roots. The signs of pathogen degradation in the cortical parenchyma, mainly in the intercellular spaces, and the increase of a physical barrier in epidermal and sub-epidermal cell wall-media lamella and intercellular spaces by impregnation with phenol-like compounds strongly suggest that α-cinnamomin induced in chestnut defence reactions against P. cinnamomi.

Induction of defence responses by cinnamomins against Phytophthora cinnamomi in Quercus suber and Quercus ilex subs. rotundifolia

“…Their action is not genus-or cultivar-specific and not only elicitins from Phytophthora but also from Pythium, like oligandrin play this role. Plants in the family Fagaceae as shown here and in other reports (Medeira et al 2012a andMedeira et al 2012b) using various approaches, display defence responses induced by elicitins.…”

“…In addition, recent cytological and physiological studies showed that cryptogein (elicitin secreted by Phytophthora cryptogea) and capsicein (secreted by Phytophthora capsici) induced a resistance response on cork oak against infection by P. cinnamomi (Medeira et al 2012a) and that α-CIN has the same effect in Castanea sativa (Medeira et al 2012b). In the present work we show that α-CIN induces a defence response to the infection by P. cinnamomi in Q. suber and in Q. ilex as well.…”

“…However, oligandrin, an elicitin-like protein secreted by Pythium oligandrum, was shown to induce systemic resistance to Fusarium oxysporum and Botrytis cinerea in tomato and grapevine, respectively (Benhamou et al 2001;Mohamed et al 2007). Also, recent histological and ultra-structural studies (Medeira et al 2012a(Medeira et al , 2012b, assessing of changes in fatty acid composition of roots and leaves, and gas exchanges and fluorescence analysis (Medeira et al 2012a) have documented that cryptogein and capsicein can trigger cellular responses in cork oak roots (Medeira et al 2012a) and α-cinnamomin (α-CIN) in Castanea sativa roots (Medeira et al 2012b) during P. cinnamomi infection. This strongly suggests that a resistance defence arose against the pathogen upon elicitin treatment.…”

Strategies of attack and defence in woody plant–Phytophthora interactions

“…) and of C. sativa induced by the same peptide (Medeira et al. ) were observed, too. More recently, it was shown that α‐ and β‐cinnamomin significantly reduced the pathogen biomass in pretreated Q. suber roots which confirms the role of elicitins in promoting the protection of oak root cells against P. cinnamomi (G. Ebadzad and A. Cravador, unpublished data).…”

“…More recently, oligandrin, an ELL secreted by Pythium oligandrum was shown to induce systemic resistance to Fusarium crown and root rot in tomato plants (Benhamou et al 2001) and defence reactions against Botrytis cinerea when applied to the roots of grapevine (Mohamed et al 2007). Resistance responses of Q. suber roots against P. cinnamomi induced by the ELI-1s cryptogein, capsaicin (Medeira et al 2012b) and a-cinnamomin (Maia et al 2008) and of C. sativa induced by the same peptide (Medeira et al 2012a) were observed, too. More recently, it was shown that aand b-cinnamomin significantly reduced the pathogen biomass in pretreated Q. suber roots which confirms the role of elicitins in promoting the protection of oak root cells against P. cinnamomi (G. Ebadzad and A. Cravador, unpublished data).…”