Abstract The activity and spatial distribution of eight enzymes in adult tap root tissues colonized by R. lignosus and P. noxius are investigated. Their physiological significance in the pathogenic process is discussed

B &amp

D Nandris

J P Geiger

M Nicole

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Sonderdruck. aus European Journal of Forest Pathology, 
Band 15 (1985), Heft 5-6, S. 316-319 
V E R L A G  P A U L  P A R E Y .  S P I T A L E R S T R A S S E  12. H A M B U R G  1 
Alle Rechte, auch die der Ubersetzung, des Nachdrucks, der photomechanischen Wiedergabe und der Speicherung in 
Datenverarbeitungsanlagen, vorbehalten. 0 1985 Verlag au1 Parey, Hamburg und Berlin f 
Ofice de la Recherche Scientifique et Techniqr4e ONtre-mer- Abidjan - Côte d'Ivoire 
The aggression of Hevea brasiliensis by Rigidoporus lignosus 
and Bhellinus noxius : some biochemical events 
By J. P. GEIGER, M. NICOLE, D. NANDRIS and B. &o 
1 U. S. Copyright Clearance Center Code Statement: 0300-1237/85/1505-0316/$02.5d/0 
I Eur. T. For. Path. 15 (1985) 316-319 1 . >  
Abstract 
The activity and spatial distribution of eight enzymes in adult tap root tissues colonized by R. lignosus 
and P. noxius are investigated. Their physiological significance in the pathogenic process is discussed. 
1 Introduction 
Rigidoporus lignosus and Phellinus noxius, Polyporaceae, are widespread white rot parasites 
in equatorial and humid tropical zones. Even though they attack a large number of shrubby 
species (CHEVAUGEON 1959), they exist in equilibrium in the natural forest. They are of 
The aggression of Hevea brasiliensis by Rigidoporus ligiiosus 317 
practical importance, at least in Africa, since they are the most dangerous root parasites of 
rubber trees. 
The main purpose of the present work is to correlate the parasite attack with changes of 
host tissues (lignified roots) and with enzyme activities,chosen for their possible participa- 
tion in tissue degradation. After an estimation of the leyel of the biochemical disturbances, 
the origin of the enzymes (host or parasite) and their possible role in the pathogenic process 
are discussed. 
2 Materials and methods 
The enzyme excretion abilities of R. lignosus and P. noxius were tested by measuring, in 
culture filtrates, the activity of carboxymethyl-cellulase, pectinase, phosphatase, ß-glucosi- 
dase, a- and ß-galactosidase, laccase and peroxydase. 
In order to estimate the degree of enzyme disturbances in host tissues caused by the para- 
site attack, extracts of healthy (H) and infected (I) tissues from partially invaded Heveu tap 
roots were examined for quantitative and qualitative enzyme activities. 
The spatial distribution of enzymes in partially invaded tap roots was investigated on the 
following samples : 
- Healthy tissues (H), sampled much ahead of parasite progression (Control), 
- Healthy front tissues (HF), sampled near the progression front, 
- Parasitized front tissues (IF), 
- Parasitized tissues (I) removed much behind the front (((old” colonized tissues), 
- Parasitized alveolar type tissues (IA) (only in the case of infection by P. noxius). 
Electrophoresis of enzymes were realized as described by SMITHIES (1 955). 
Culture medium (Wood dust), culture filtrate, wood extracts, enzyme assays were 
prepared or realized as earlier described (GEIGER 1975; GEIGER et al. 1976; NICOLE et al. 
1982). 
3 Results 
The main results are as follows : 
1. Compared to the enzyme activities which can be extracted from healthy tissues, extracts 
from parasitized tissues exhibit a number of enzymatic modifications, both at quantitative 
and qualitative levels. 
- qualitatively: three enzymes are present only in parasitized tissues : CM-cellulase, pecti- 
nase and laccase for which their major participation in the pathogenic process may be 
presumed. 
- quantitatively: with the exception of phosphatase and partially of ß-glucosidase, enzyme 
activities in infected tissues are much higher than those in healthy tissues; these enzymes 
are: a and ß-galactosidases and peroxidase. 
2. R. lignosus and P. noxius both excrete glycosidases, polyoxidases and laccase, but at 
activity levels which are specific to each fungus; there is a predominance of laccase activity in 
the case of R. lignosrts and hydrolases in the case of P. noxius. These same quantitative varia- 
tions exist in parasitized tissues; so that in terms of the relative proportions of the different 
enzymatic activities, the extracts of these tissues are quite similar to those of the homologous 
culture filtrates. 
3. The spatial distribution of enzyme activities shows that, with exception of the phospha- 
tase and the peroxidase, the activities increase according to the sequence H+ HF+ IF+ I 
+ IA tissues. They are highest in the alveolar tissues which are thus incapable of any type of 
reaction requiring the integrity of the protein synthesis system. Therefore it can be assumed 
that all those enzymes present in infected tissues are of fungal origin. 
4. Electrophoretical comparisons of isophosphatases and isoperoxidases from healthy and 
318 J.  P. Geiger, M. Nicole, D. Nandris and B. Rio 
infected tissues (by R. lignosus and P. noxiz4s) and from homologous culture filtrates show 
that the phosphatase in infected tissues is of fungal origin, whereas the peroxidase increase in 
IF type tissues corresponds to a host reaction. 
5. The enzymes secreted by the pathogens are well adapted to the degradation of plant 
tissues. The action of enzymes contained in culture filtrates causes the release of various 
saccharides (monomers and oligomers) from insoluble Heveu lignocellulose. 
Similarly, laccase must play a role in lignin degradation as shown by the fact that one of 
' these enzymes (laccase LI) produced by R. lignosus causes both the condensation and the 
depolymerisation of lignin (GEIGER et al. 1983). 
4 Discussion - Conclusion 
According to all these data we can propose some hypotheses or conclusions about the dis- 
turbances caused by the parasite attack of host roots, their signification and the role of the 
enzymes that are involved. 
1. With exception of peroxidase, the enzymes that are present in infected tissues are of 
fungal origin. They are involved in root tissue degradation. R. lignosus and P. noxius degrade 
both polysaccharidic and lignin fractions and therefore they must be classified among the 
white rotting fungi. 
2. The increase of the peroxidase activity in IF tissues is a response of the host against the 
parasite aggression. As shown by GEIGER and HUGUENIN (1981) this enzyme polymerizes 
the p-coumarylic and sinapinylic alcohols and thus it may be involved in reaction lignin 
synthesis leading to the cell wall thickening that could be observed in infected tissues 
(NICOLE et al. 1982). 
3. Quantitative differences and especially the ratio of laccase and polysaccharidases should 
have an effect on the relative capacity of the two fungi to degrade the different polymers of 
the cell-wally and thus the different root tissues. In practice, it is expected that P. noxiws is 
more active than R. lignosus on polysaccharide structures and thus in tissues which are 
richest in cellulose, xylan and pectic materials, whereas the inverse should be true on highly 
lignified tissues. 
The comparisons between lignin contents of wood sticks infected either by R. Zignosus or 
P. noxius agree with this hypothesis. In fact the former exhibits a tendency to a more rapid 
degradation of the lignin fraction whereas the latter degrades somewhat more rapidly the 
polysaccharidic fraction as the lignin one. 
In agreement with the biochemical data, the histological observations show that P. noxius 
degrades cortical tissues i. e. weakly lignified tissues, more rapidly and more completely 
than R. lignosus does. O n  the other hand, R. lignosus degrades more rapidly the woody 
lignin-rich structure of the xylem than the cortical tissues. Nevertheless P. noxius degrades 
quite well the lignified tissues of xylem. This suggests that the lignin degrading equipment of 
P. noxius is not a limiting factor but that, on the contrary, the weak hydrolitic equipment of 
R. lignosus limits the degradation abilities of this parasite on polysaccharidic structures 
(NICOLE et al. 1984). 
Summary 
Parasite aggression causes a considerable disturbance in the enzyme equipment of Hevea root tissues. 
The enzymes present in those tissues are of fungal origin and participate in the degradation of polymers 
in different cell walls of the host. Regarding the ratio between polysaccharidase and laccase activities 
P. noxius may preferentially attack weakly lignified tissues whereas R. lignosus would be more active on 
lignified tissue of the xylem than on cortical tissues. The increase of peroxidase activity corresponds to a 
host reaction and may participate in the defence mechanisms of Hevea bvasiliensis against the invading 
parasites. 
The aggression of Hevea brasiliensis by Rigidoporus lignosus 319 
Résumé 
L'attaque &Hevea brasiliensis par Rigidoporus lignosus et Phellinus noxius: 
dgférentes manifestations biochimiques 
L'agression parasitaire provoque une perturbation considérable au niveau de l'équipement enzyma- 
tique des tissus racinaires de l'Hévéa. Les enzymes présentes dans les tissus parasités sont d'origine 
fongique et participent à la dégradation des différents polymères pariétaux des tissus de l'hôte. La 
proportion entre hydrolases (plus particulièrement polyosidases) et laccase diffère suivant le parasite et 
suggère une attaque préférentielle des structures polysaccharidiques par P. noxius et une activité 
privilégiée à l'encontre des tissus lignifiés par R. lignosus. 
L'accroissement de l'activité peroxydasique dans les tissus parasités correspond à une réaction de 
l'hôte. Cette enzyme est susceptible de participer aux mécanismes de défense de l'Hévéa. 
Zusammenfassung 
Der Befall von Hevea brasiliensis durch Rigidoporus lignosus und Phellinus noxius: 
Der Angriff von Pathogenen verursacht erhebliche Störungen im Enzymhaushalt des Wurzelgewebes 
von Hevea brdsiliensis. Die Enzyme in den befallenen Geweben stammen von den Pilzen und sind am 
Abbau der verschiedenen Zellwandbestandteile der Wirtszelle beteiligt. Betrachtet man das Verhdtnis 
zwischen Polysaccharidase- und Laccaseaktivität, so dürfte P. noxius bevorzugt schwach lignifiziertes 
Gewebe befallen, während R. lignosus eher im lignifizierten Gewebe des Xylems als in der Rinde aktiv 
sein dürfte. Der Anstieg der Peroxidaseaktivität geht mit einer Reaktion des Wirtes Hand in Hand und 
dürfte Teil einer Abwehrreaktion von H. brasiliensis gegen die eindringenden Pathogene sein. 
a' einige biochemische Zusammenhänge 
References 
CHEVAUGEON, J., 1959: Le problème des pourridiés en Côte d'Ivoire. Rev. Mycol. 23 (l), 39-58. 
GEIGER, J. P., 1975: Aspects physiologiques et biochimiques de la spécialisation parasitaire. Cas des 
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cultures tropicales, Lyon. 
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271-282. 
Authors' address: ORSTOM, Centre d'Adiopodouné, Laboratoire de Phytopathologie, B. P. V-51, 
Abidjan, Ivory Coast 


The aggression of Hevea brasiliensis by Rigidoporus lignosus and Bhellinus noxius : some biochemical events

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The aggression of Hevea brasiliensis by Rigidoporus lignosus and Bhellinus noxius : some biochemical events

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