Phytophthora cinnamomi
has been reported to be
regularly associated
with cork and holm oak decline. This oomycete secretes elicitins, a
group of unique highly conserved pr
oteins that can enhance plant
defence reactions

Cravador, A.

Maia, I.

Medeira, C.

Melo, Eduardo P.

Microscopy and Microanalysis

Sapientia

Quercus suber Infected by Phytophthora cinnamomi.  Effects at Cellular Level of Cinnamomin on Roots, Stem and Leaves  I. Maia a,*, C. Medeira a, E. Melo a, A. Cravador b,  a INRB. Estação Agronómica Nacional, Quinta do Marquês, 2784-505 Oeiras, Portugal. * isabel.maia@ etcabo.pt b Universidade do Algarve, FERN, Campus de Gambelas, 8005-139 FARO, Portugal  Phytophthora cinnamomi has been reported to be regularly associated with cork and holm oak decline. This oomycete secretes elicitins, a group of unique highly conserved proteins that can enhance plant defence reactions. In our previous work it was shown that the absorption of one of these elicitins─ α-CIN─ by the roots of cork and holm oak at concentrations of 500 μg and 1 mg/ml reduced P. cinnamomi viability and its progression into internal tissues.  The objectives of the present work were to study the restriction of host tissue colonization and the loss of pathogen viability in the roots treated with lower concentration of α-CIN, and to verify structural alterations at cellular level induced by this elicitin in aerial part of the plantlets.  Roots of Quercus suber seedlings two month old were immersed in aqueous α-CIN solutions [250 µg/ml] and [100 µg/ml] during 24 h. Roots were then inoculated with P. cinnamomi.  The samples pre-treated with α-CIN at the two concentrations and inoculated with P. cinnamoni revealed similar histological and cytological aspects. The hyphae were mainly intercellularly located, restricted to the external cortex (Figs.A and B). The treatment induced loss of pathogen viability and it was evident the pathogen membranar degradation, loss of organelles and reduction of  Microsc Microanal 14 (supp 3), 2008146doi: 10.1017/S1431927608089708 Copyright 2008, LASPMFigs. A, B. Cortical root parenchyma infected with P. cinnamomi. A- non-treated with α-CIN; B- α-CIN treated. Figs. C, D.  P. cinnamomi cells.C-in α-CIN treated roots; D-in α-CIN non-treated roots.     cytoplasm density (Figs.C and D). The hyphae were mainly intercellularly. In stem of α-CIN pre-treated plants, the external cortical and medullar parenchymas concentrated osmiophylic materials in vacuoles. In leaves the histological structure was maintained, but in spongy parenchyma the chloroplast ultrastructure was modified. In leaves the histological structure was maintained, but in spongy parenchyma the chloroplast ultrastructure was modified.  The loss of viability of the pathogen and its confinement to the root cortex are in accordance with our previous observations as well as those by other authors [1,2,3,4]. The increase of accumulation of osmiophylic materials, probably phenol compounds, in the stem suggests a defence response [1,2,3,4]. In leaves the chloroplasts are the most sensitive organelles but did not appear much damaged, allowing the recovering of the plantlets. We can conclude that α-CIN induced a defence response against P. cinnamomi in cork oak, at 100 µg/ml and no irreversible damage occurred. References: [1] J. Lheirmnier, et al. Phytopathology, 93 10 (2003) 1308. [2] C. Medeira et al. IUFRO Tree Biotech. Congress, 2007, Ponta Delgada, Azores. [3] N. Mohamed, et al. Phytopathology, 97 5 (2007) 611. [4] K. Piccard, et al. Plant Physiology, 124, (2000) 379.  3 20 A 0,3 C DB 147Microsc Microanal 14 (supp 3), 2008

Quercus suber infected by Phytophthora cinnamomi: effects at cellular level of cinnamomin on roots, stem and leaves

Universidade do Algarve

Quercus suber Infected by Phytophthora cinnamomi. 
 Effects at Cellular Level of Cinnamomin on Roots, Stem 
and Leaves  
I. Maia a,*, C. Medeira a, E. Melo a, A. Cravador b,  
a INRB. Estação Agronómica Nacional, Quinta do Marquês, 2784-505 
Oeiras, Portugal. * isabel.maia@ etcabo.pt 
b Universidade do Algarve, FERN, Campus de Gambelas, 8005-139 
FARO, Portugal  
Phytophthora cinnamomi has been reported to be regularly associated 
with cork and holm oak decline. This oomycete secretes elicitins, a 
group of unique highly conserved proteins that can enhance plant 
defence reactions. 
In our previous work it was shown that the absorption of one of these 
elicitins─ α-CIN─ by the roots of cork and holm oak at concentrations 
of 500 μg and 1 mg/ml reduced P. cinnamomi viability and its 
progression into internal tissues. 
 
The objectives of the present work were to study the restriction of host 
tissue colonization and the loss of pathogen viability in the roots 
treated with lower concentration of α-CIN, and to verify structural 
alterations at cellular level induced by this elicitin in aerial part of the 
plantlets. 
 
Roots of Quercus suber seedlings two month old were immersed in 
aqueous α-CIN solutions [250 µg/ml] and [100 µg/ml] during 24 h. 
Roots were then inoculated with P. cinnamomi. 
 
The samples pre-treated with α-CIN at the two concentrations and 
inoculated with P. cinnamoni revealed similar histological and 
cytological aspects. The hyphae were mainly intercellularly located, 
restricted to the external cortex (Figs.A and B). 
The treatment induced loss of pathogen viability and it was evident the 
pathogen membranar degradation, loss of organelles and reduction of  
Microsc Microanal 14 (supp 3), 2008146
doi: 10.1017/S1431927608089708 Copyright 2008, LASPM
Figs. A, B. Cortical 
root parenchyma 
infected with P. 
cinnamomi. A- non-
treated with α-CIN; 
B- α-CIN treated. 
Figs. C, D.  P. 
cinnamomi cells.
C-in α-CIN 
treated roots; D-
in α-CIN non-
treated roots. 
 
 
 
 
cytoplasm density (Figs.C and D). The hyphae were mainly 
intercellularly. 
In stem of α-CIN pre-treated plants, the external cortical and medullar 
parenchymas concentrated osmiophylic materials in vacuoles. In 
leaves the histological structure was maintained, but in spongy 
parenchyma the chloroplast ultrastructure was modified. In leaves the 
histological structure was maintained, but in spongy parenchyma the 
chloroplast ultrastructure was modified.  
The loss of viability of the pathogen and its confinement to the root 
cortex are in accordance with our previous observations as well as 
those by other authors [1,2,3,4]. The increase of accumulation of 
osmiophylic materials, probably phenol compounds, in the stem 
suggests a defence response [1,2,3,4]. In leaves the chloroplasts are the 
most sensitive organelles but did not appear much damaged, allowing 
the recovering of the plantlets. 
We can conclude that α-CIN induced a defence response against P. 
cinnamomi in cork oak, at 100 µg/ml and no irreversible damage 
occurred. 
References: 
[1] J. Lheirmnier, et al. Phytopathology, 93 10 (2003) 1308. 
[2] C. Medeira et al. IUFRO Tree Biotech. Congress, 2007, Ponta 
Delgada, Azores. 
[3] N. Mohamed, et al. Phytopathology, 97 5 (2007) 611. 
[4] K. Piccard, et al. Plant Physiology, 124, (2000) 379.  
3 
20 A 
0,3 C 
D
B 
147Microsc Microanal 14 (supp 3), 2008


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Quercus suber infected by Phytophthora cinnamomi: effects at cellular level of cinnamomin on roots, stem and leaves

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