Evans, K.

Storey, G.W.

Name not available

Cellular responses of three susceptible cultivars of potato to invasion by the juveniles of Globodera pallida

Horizon / Pleins textes

Notes brèves 
oflicinarunz) in Sind region. NRC, Univ. Karachi, Res. Bull., OOSTENBRINK, M. (1960). Estimating nematode population by 
'(Eds). Nematology. Chape1 Hill, Univ. N. Carolina Press : 
of cereals and  fruits of Pakistan  with special reference to ROMAN, J. (1965). Nematodes of Puerto  Rico,  the  genus 
Quinisulcius solani Maqbool, 198-7. Ph. D. Thesis, Univ. Helicotylenchus Steiner,  1945  (Nematoda : Hoplolaimidae), 
Iiarachi, 190 p. Tech. Pap. Univ. Puerto Rico agric. Exp. Stn, 41 : 1-22. 
1 : 00-00. some selected  metho s. In : Sasser J. N. & Jenkins W. R. 
MRQBOOL, M. A. (1984). Studies on plant  parasitic  nematodes 85-102. 
Accepti  pour  publication le 23 ju in  1986. 
CELLULAR RESPONSES OF THREE SUSCEPTIBLE CULTIVARS OF POTATO 1'0 INVASION 
BY THE JUVENILES OF GLOBODERA  PALLIDA 
Gordon W. STOREY* and  Ken EVANS** 
A general distinction between the cellular responses 
of the roots of resistant and susceptible cultivars of 
potato to invasion by potato cyst nematodes is reported 
as hypersensitivity. This condition is expressed  by 
localised lignification and necrosis around the nematode 
and the developing syncytium, in resistant cultivars. 
Eventually the lignification walls  off the syncytium, 
thereby preventing its continued expansion (Hoopes, 
Anderson & Mai, 1978;  Rice,  1983,  Rice, Leadbeater & 
Stone, 1985). 
Susceptible cultivars allow the incorporation of cells 
into the syncytium and their further proliferation to 
proceed unchecked; simple mechanical damage without 
lignification is the only  evidence of the passage of the 
nematode through  the root tissues. 
Evans, Greet and Inge (1983) reported that potato 
cultivars with no resistance to Globodera  pallida Stone 
exhibited different degrees of tolerance to this 
nematode. The same authors described experiments 
which related these differences in tolerance to  the 
interaction between the nematode and  the wilt fungus 
Verticil l ium dahliae (Kleb.). Three cultivars of potato, 
Maris Anchor, Maris Peer and Pentland Javelin, gave 
very different responses to invasion by G. pallida. 
Sixty tuber pieces  bearjng  single sprouts of the three 
potato cultivars  were incubated on 2 "/O water aga  (contai- 
ning 0.005 O/O streptomycin  sulphate) at 20" in the dark. 
After ten days,  10 p of 2 O/O carboxymethylcellulose 
containing 20 newly hatched juveniles of G. pallida were 
placed on roots growing on the surface of the agar; 
additions were made at the root tip or at 2.5 cm,  4.5 cm, 
6.5 cm or 8.5 cm from  the root tip. The plants were then 
returned to the incubator and 1.0 cm segments around 
the inoculation points harvested eight days later. The 
segments were  fixed immediately in F.A.A. and 
processed through a tertiary butyl alcohol  series to wax 
(Southey,  1970);  10 pm sections were stained in either 
Sudan Black B or Safranin O and Fast Green. 
Fig. 1 A-C shows the structure of the root of each 
cultivar at 2.5 cm from the tip. Pentland Javelin 
(Fig. 1A) has large diameter roots, a well developed 
cortex of up to eleven layers of thick walled cells, a 
thickened epidermis, no distinct hypodermis and a well 
developed pentarch xylem. Maris Peer (Fig. 1B) has 
thinner roots, a less dèveloped pentarch xylem, up  to 
eight layers of thinner walled cortical cells and possesses 
a well developed hypodermis thickened on its radial and 
outer tangential walls. Maris Anchor (Fig. 1C) has very 
thin roots, a tetrarch xylem, a cortex with up to only  five 
layers of large thin walled  cells of which the  outer layer 
forms a distinct hypodermis. 
Pentland Javelin exhibited the expected susceptible 
response to invasion  by nematodes (Fig. 2A) with little 
tissue damage and hypersensitivity shown only by those 
cells  adjacent to the nematode and with no lignification 
around the developing syncytium. However, Maris Peer 
(Fig.  2B) and  Maris Anchor (Fig. 2C) both exhibited a 
marked hypersensitivity in several  layers of cells around 
the nematode, which in Maris Anchor spread rapidly 
through the surrounding tissue often resulting in its 
collapse. Lignification around  the syncytium  also 
occurred but was not  pronounced; evidently the 
* Luton  College of Higher  Education,  Park  Square,  Luton, LUI 3Ju, England. 
** Nematology  Dept.  Rothanlsted  Experimental  Station,  Harpenden, Herts, AL5 2JQ England. 
113 
G. W: Storey & K. Evans 
Fig. 1. Transverse sections from potato roots.  Cultivars : 
Pentland Javelin (A) x 200; Maris Peer (B) x 250; Maris 
Anchor (C) x 256. Endodermis (e),  Cortex (c), Hypodermis 
(hl. 
114 
Fig. 2. Cellular responses of potato roots to invasion by G. 
pallidu juveniles. Cultivars : Pentland Javelin (A) x 500; 
Maris Peter (B) x 750; Maris Anchor  (C) x 640. Nematode 
(n),  Hypersensitive  response  (hr). 
Revue Neinatol. 10 (1) : 113-115 (19871 
Notes brèves 
development of the syncytium was not impeded as no 
degenerate syncytia  were  seen. 
It is  recognised that  the cellular responses of partially 
or completely resistant cultivars can  take different forms 
according to their complement of resistance genes (Rice 
& Stone, 1983).  However, previous studies have 
concluded that al1 susceptible cultivars show  similar ce11 
responses (Hoopes, Anderson & Mai, 1978) viz. an 
insensitivity to tissue damage with necrosis confined to 
the cells adjacent to the  nematode  and with no necrosis 
around  the syncytium, although Huijsman, 
Klinkenberg and Den  Ouden (1969) noted greater or 
lesser amounts of necrosis around syncytia  when they 
degenerated after the nematodes completed their 
development. In  the present experiments Pentland 
Javelin exhibited the typical susceptible response. 
However, the susceptible cultivars Maris Peer and Maris 
Anchor both showed extensive necrosis in the tissues 
surrounding  the  nematode; both of these cultivars also 
have a lignified hypodermis and produce lignitubers in 
response to invading fungal hyphae. Pentland Javelin 
does not have a hypodermis and although it does 
produce lignitubers, it is not so prone to produce a 
hypersensitive response to the nematode. 
A range of responses to nematode invasion is already 
recognised in resistant cultivars; apparently, a range of 
responses may  also occur in susceptible cultivars. 
Accepté pour  publication le 6 aotit  1986. 
REFERENCES 
EVANS, K., GREET,  D. N. & INGE, N. (1983).  Interactions  of 
potato  cyst-nematode  and Verticillium dahliae. Rothamsted 
exp. Statn,  Rep. 1982, Part 1 : 161. 
HOOPES, R. W., ANDERSON, R. E. & WI, W. F. (1978). 
Interna1  response  of  resistant  and  susceptible  potato  clones 
to invasion  by  potato cyst nematode Heterodera rostochiensis. 
Nematropica, 8 : 13-20. 
HUIJSMAN, C. A., KLINKENBERG, C. H. & DEN OUDEN, H. 
(1969).  Tolerance  to Heterodera rostochiensis Woll., among 
potato  varieties  and  its  relation  to  certain  characteristics of 
root  anatomy. Europ.  Potato J., 12 : 134447. 
RICE, S. L. (1983). 7'he anatomical response to cyst nematode 
invasion in potatoes with resistance derived from Solanum 
vernei and S. tuberosum ssp. andigena.  Ph.  D.  Thesis,  Univ. 
Birmingham,  215 p. 
RICE, S.  L., LEADBEATER, B. S. C. & STONE, A. R. (1985). 
Changes in ce11 structure in roots of resistant potatoes 
parasitized  by  potato  cyst-nematodes. 1. Potatoes  with 
resistance gene HI derived from Solanum tuberosum ssp. 
andigena. Physiol. Pl. Pathol., 27 : 219-234. 
RICE, S. & STONE, A. R.  (1983).  Resistant  response  to  potato 
cyst-nematode. Rothamsted exper. Statn,  Rep. 1982, Part 1 : 
SOUTHEY, J. F. (1970). Laborato y methods for work with  plant 
and soi1 neinatodes. London,  H.M.S.O.,  Ministry  of 
Agriculture, Tech. Bull. No. 7, : 148 p. 
160-161. 
INCREASE OF THE CHEMICAL  OXYGEN  DEMAND  DURING 
THE GROWTH  IN HETERODERA SACCHARI 
Georges REVERSAT" 
In nematodes species which remain vermiform at any 
stage of development, quantitative study of the growth 
may be approached by measuring increases of length 
and width (Bird, 1971; Ohba & Ishibashi, 1981). In  the 
case of species which become swollen at later stages, 
such as MeZoidogyne javanica, Bird (1959)  showed that 
measurement of area with the camera lucida gave a 
better appreciation of the increase in size. This  author 
however suggested that " measurements of volume or 
weighing would give better representation of the rate of 
growth. The size of, these creatures predisposes against 
these techniques, however ". In the present work, 1 
measured the growth of females of Heterodera sacchan' 
by means of the chemical  oxygen demand (COD), that 
is the oxygen required for  the complete oxidation of the 
organic matter in  the nematode with an oxidizing 
chemical (Reversat,  1981 a) 
Material  and methods 
Heterodera sacchari was reared on two cultivars of rice 
(Oryza sutivu) : Morobérékan, traditional in Ivory Coast, 
and IR 1529, introduced from the International Rice 
* Laboratoire de Nématologie, ORSTOM, B.P. 1386, Dakar, Sénégal. Present address : Laboratoire de Néwatologie, ORSTOM, 
B.P. 1286, Pointe-Noire, Congo. 
Revue Néntatol. 10 (1) (1987) 115 


Cellular responses of three susceptible cultivars of potato to invasion by the juveniles of Globodera pallida

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