Badra, T.

Ismail, S.A.

Name not available

Accelerating the role of phenylalanine in shunting sex differentiation of Rotylenchulus reniformis by means of some nutrient formulae

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Accelerating the role of phenylalanine in shunting 
sex  diflierentiation of Rotylenchuhs reniformis by means 
of some nutrient formulae 
Taysir BADRA and Samir A. ISMAIL 
National  Horticulfural.  Research  Institute, P M B  5432,  Ibadan,   Niger ia   and   Depar tment  of Biochernistry, 
Facul ty  of Agricul ture,   Cairo  Universi ty ,   Giza,   Egypt .  
SUMMARY 
Fertilization  with  nitrogen  and  phosphorus  supplemented  with  several  microelements  influenced  the  multiplica- 
tion  and sex  differentiation of Rotylenchulus  reniformis associated  with  cowpeas.  Phosphorus  fertilization  reduced 
nematode  build  up  and  increased  percentages of non-feeding  males,  while  fertilization with  other  elements  either 
did not affect, or delayed  sex  differentiation. 
Total  amino  acid  content showed no  significant  increases or decreases  in  roots, but significant  difforences  occurred 
among  treatments  with  regard  to  the  content of phenylalanine  and  tyrosine.  Treatments  induced  slight  variations 
in   the phenylalanine  content  in  tissues,  which  correlated well with  alterations in sex  differentiation of associated 
R .  reni formis .  When  phenylalanine  constituted 0.50-0.89 % of the  total  analyzed  amino  acids,  sexual  differentiation 
of the  larvae  to  either sex was delayed or stopped (51-61 % larvae  compared  with  45%  in  controls) ; when  phenyla- 
lanine  constituted 1.33-1.48% of the  total  amino  acid,  larvae  preferentially  differentiated  as  males  (53-79%  males 
compared  with  25%  in  controls). It is suggested that  the increase in  phenylalanine  could  be  important  due  to  its 
role as a precursor  in  the  synthesis of phenylpropionic  phenolics  in  cowpeas. 
RÉSUMÉ 
Renforcement  de  l’action  de la phe’nylalanine  dans  la  détermination  du  sexe  chez Rotylenchulus  reniformis 
p a r  le moyen  d e  quelques  formules  de  fumure 
La  fumure  azotée  et  phosphorée  additionnée  de  plusieurs  microéléments  a modifié la  multiplication e t  la  déter- 
mination du sexe chez Rotylenchulus  reni formis  associé à Vigna  ungu icu la ta .  La fumure phosphorée a réduit le 
développement,  des  populations  de  nématodes et  augmenté le  pourcentage  de  mâles,  alors  que  les  autres  fumures 
n’avaient  aucun effet ou retardaient  la différenciation  sexuelle. 
La  teneur  totale  des racines  en  amino-acides  est  restée  invariable  mais  des  différences  significatives ont  été  obser- 
vées  entre  les  traitements en ce qui concerne leur contenu en phénylalanine et   en tyrosine.  Les  traitements  ont 
provoqué des variations limitées du contenu des tissus en phénylalanine qui sont corrélées avec des altérations 
dans la différenciation sexuelle chez les R. reni formis  associés à la plante. Quand la phénylalanine représentait 
0,50-0,89%  des  acides  aminés  totaux  la  différenciation  sexuelle  des  larves  vers  l’un ou l’autre  sexe  était  retardée 
ou stoppée  (51-61 % des  larves  contre  45%  chez  les  témoins) ; quand  la  phénylalanine  représentait  1,33 à 1,48% 
des  acides  aminés  totaux,  les  larves  évoluaient  préférentiellement  en  mâles  (53-79 % de  mâles  contre  25%  chez  les 
témoins).  Les  auteurs  émettent  l’hypothèse  que  la  phénylalanine  jouerait  un  rôle  comme  précurseur  des  composés 
phényl-propioniques chez Vigna unguiculata.  
There  is  little  information  about  the effect of on  nematodes  directly,  or  indirectly  through 
the aromatic phenylalanine and tyrosine amino other  by-products,  restricting  the  growth of 
acids on parasitism and sex differentiation of nematodes in tissues (Badra & Elgindi, 1979 ; 
nematodes. These aromatic compounds can act Giebel,  1970). In  this  study we investigated  the 
Revue  Nématol.  4 ( 2 ) :  209-212 (1981) 209 
T .  B a d r a  di. S . A .  I s m a i l  
influence of some inorganic  fertilizers  on  sex  dif- replicated  six  times ; the  xperiment  lasted 
ferentiation  in Rotylenchulus reniforrnis in cow- from August to  October and was harvested in 
pea  roots. early  November. At  harvest  nematode  densities 
in each pot were estimatecl from 250 g of soil 
Materials and methods 
Cowpea plants, Vigna unguiculata L.  Walp 
cv. Azmerely, were grown, in a greenhouse at  
25-300, in  15 cm Clay pots  containing .1 kg 
autoclaved Clay loam soil, inoculated  with 3 O00 
individuals of reniform nematodes, Rofylenchu- 
lus reniformis Linford 2% Oliveira, 1940.. The 
nutrient  solutions  symbolized  in  Table 1 as NO, 
N2, N4, PO, P2, P4 and NlPl including five 
microelement  supplements  (Cu,  0.025 ; MO, 
and 2 g of fresh roots, respectively extracted 
by Oostenbrink’s (1960) and the fragmentation 
(Taylor 2% Loegering, 1953) techniques. Amino 
acids  were  xtracted from 0.25  root  issues, 
separated by means of two-dimentional paper 
chromatograpby  (Block,  Durrum & Zweig, 
1958),  and  characterized by  their  adsorption. 
0.001 ; B, 0.793 ; Mn, 0.056 and  Fe, 0.178 meq/l) 
were applied 200 ml/pot, ten days after nema- 
tode inoculation, a t  six weekly intervals. Each 
treatment and the control (no nutrients) were 
Results 
The fertilizers with nitrogen and phosphorus 
plus microelements significantly depressed soil 
and root populations of R. renifornzis. The sex 
ratio  and  percent of the non-feeding  males  were 
drastically altered by PO, P2 and P4 formulae 
(Fig.  1). Development  and  sex  differentiation of 
the  larvae were markedly affected by  the  NlPl 
formula.  About  61% of the ’ soil nematodes 
remained  as  exually  undifferentiated  larvae 
compared  with  45%  larvae  in  the  control. 
The  total  amino acid content of treated  roots 
varied  with  treatments,  but was not significantly 
different  from  untreated  controls  (Tab.  2).  There 
were differences in the relative concentrations 
of phenylalanine  and  tyrosine  among  treatments. 
Figure 1 shows the changes in percentage com- 
position for these  two  amino  acids  in  roots  and 
sex  differentiation of R. reniformis. The  per- 
Table 1 
Macroelement  composition of applied  nut.rient  formulae 
Compound 
and  Treatment  
NO : 
K,SO, 
CaSO, 
NaH,PO,.  2H,O 
MgSO, * 7H20 
KNO, 
Ca( NO,) , . 4 H  ,O 
NaH,PO,.  2H,O 
NaNO, 
KNO, 
Ca(NO,), .4H,O 
NaH,PO,. 2H,O 
Mg(NO3),.6H,O 
NaNO, 
N I  P l  : 
KNO, 
Ca(NO,), .4H,O 
NaH,PO,.  2H,O 
N 2  : 
hiIg(NO,), . 6H,O 
N 4  : 
MgSO,. 7H,O , 
Milliequivalent/ 
liter 
4.50 
34.33 
9.05 
30.61 
5.17 
47.11 
9.05 
127.41 
, 31.59 
5.17 
47.11 
9.05 
31.59 
491.44 
5.17 
47.1 1 
9.05 
30.61 
- .  
Compound 
and Treatrnent 
PO :. 
KNO, 
Ca(NO,), .4H,O 
Na,SO, 
MgSO, . 7H,O 
P2 : 
KNO, 
Ca(NO,), . 4H20 
NaH,PO,. 2H,O 
MgSO, * 7H,O 
KNO, 
Ca(NO,), .4H,O 
NaH,PO,. 2H,O 
P d  : 
MgSO, . 7H,O 
Milliequivalent/ 
liter 
5.17 
47.1 1 
8.03 
30.61 
5.17 
47.11 
18.10 
30.61 
5.17 
44.71 
36.19 
30.61 
210 Rerrue Nématol. 4 ( 2 ) :  209-212 (1981) 
Phenylalanine  and  sex  dif ferenfiation of Rotylenchulus  reniformis 
PHENYLALANINE TYROSINE - Percentage of moles - - -- Percentage of females 
O J  , 
0.50 O b  0.89 094;04 lj3 1 . h  1.b 
NO’ N4 NlPl N2 check PO P4 ~2 
I 
. PERCENTAGE OF AMINO  AClD 
Fig. 1. Relationship between relative amount’of phenylalanine or tyrosine and 
. proportional development of R. reni formis  stages  in  soil  and/or  roots.  An 
indicates a significant correlation, The correlation between phenylalanine and 
male/female ratio was only  very  strong  over 1.04%. 
centage composition of pllenylalanine in robts 
had : i) significant  positive and  negative correla- 
tions with percentages of males and larvae in 
soil,  respectively, ii) non significant negative 
correlations with percentage of feinales in soil 
and  numbers  on  roots,  respectively,  and iii) non- 
significant positive correlation with the nema- 
tode  sex  ratio  in soil. 
Discussion 
Present  data  suggest that  percentage com- 
position of phenylalanine and tyrosine inroots 
is linked to  sexual differentiation of R. renifor- 
mis. We suggest the presence of a shunt level 
of phenylalanine (0.94-1.04%) below which, a 
large  proportion of the  larvae  delay Pr stop 
their differentiation to either sex. Beyond that  
threshold,  sexual  differentiation is toward  higher 
percentages of males.  This  assumption’ tbat  
phenylalanine  might  play a part  in  the  present 
imbalance in sex differentiation i s  particularly 
important with reference to cowpeas. Phenyla- 
lanine  is aprimary  metabolite  in  the bio- 
synthesis  pathways  leading  to  the  phenyl- 
propionic phenolics (Street & Coclrburn, 1972), 
and. some phytotoxins  and  phytoalexins  derived 
from  phenylalanine  have been detected  in cow- 
peas,  e.g. benzoic acid,  phenylbutyric  acid, 
phaseollin,  phaseollidin and  Kievitone (Tous- 
soun ef al., 1968 ; Deverall, 1976). 
Revue Nématol. 4 (2): 209-218 (1981) 21 1 
T.  Badra  & S.A. I s m a i l  
Table 2 
Absolute and relative amounts of phenylalanine and tyrosine in cowpea roots 
after  the  application of some nutrient  formulae (pg/lOO mg dry  wt.) 
Treatmenf  
Nitrogen  level : 
NO 
N 2  
N4 
Phosphorus  level : 
PO 
P2 
P4 
N 1  Pl  
Untreated  control 
LSD 0.05 
LSD 0.01 
Phenyla lanine  
66 * *  
(0.50) 
105 ' 
(0.94) 
1 O0 
(0.69) 
108 
(1.33) 
148 * *  
(1.48) 
152 * *  
(1.41) 
111 
(0.89) 
119 
(1.04) 
20 
28 
Tyros ine  
637 * *  
(4.81) 
526 * *  
(4.71) 
1261 * *  
(8.69) 
546 * *  
(6.74) 
509 * *  
(5.07) 
477 * *  
(4.43) 
730 
(5.82) 
738 
(6.43) 
69 
94 
Tota l   amount  
of 13 inclusive 
amino  acids  
13 243 
11 161 
14  507 
8 102 
10 034 
10  772 
12 548 
11 483 
6  522 
8 877 
Values  in  parentheses  represent  percentage of each  amino acid in  the  total  composition. 
* * Significantly  different  from untreated  control  at 0.01. 
REFERENCES 
BADRA, T. & ELGINDI, D.M. (1979). The relationship 
between  phenolic  content  and Tylenchulus   emi-  
penetrans populations  in  nitrogen-amended  citrus 
plants. Reu. Nématol . ,  2 : 161-164. 
BLOCIC,  R.L., DURRUM, E.L. & ZWEIG, G. (1958). 
A M a n u a l   o f   P a p e r   C h r o m a t o g r a p h y   a n d   P a p e r  
Electrophoresis. 2nd ed., New York and  London, 
Academic  Press,  710 p. 
DEVERALL,  B.J.  (1976).  Current  perspect,ives  in
research  on  phytoalexins.  In : Friend, J. & Threfall, 
D.R. (Eds) Biochemical  Aspects  of   Plant-Parasite 
Relat ionship,  New York and  London,  Academic 
Press : 207-223. 
GIEBEL, J. (1970). Phenolic content in roots of some 
Solanaceae and  its influence  on  IAA-oxidase activity 
Accepté  pour  publication le 5 février 1981. 
~. , . 
21 2 
as an indicator of resistance to Heterodera  rosto- 
chiensis. Nematologica, 16 : 22-32. 
OOSTENBRINK, M. (1960).  Estimating  nematode  popu- 
lations  by  some  selected  methods.  In : Sasser, J.N. 
& Jenkins,  W.R.  (Eds) Nematology,  Chape1 Hill, 
Univ. North Carolina Press : 85-102. 
STREET,  H.E. & COCKBURN, W.  (1972).  Secondary 
plant products. In : Street, H.E. & Cockburn, W. 
(Eds) Plan t  Me tabo l i sm ,  Oxford, Pergamon Press : 
186-21 1. 
TAYLOR,  A.L. & LOEGERING,  W.Q.  (1953).  Nematodes 
associated with lesions in  abaca. Turrialba,  31 : 
TOUSSOUN, T.A., WEINIIOLD, A.R., LINDERHAM, R.G. 
& PATRICK, Z.A. (1968).  Nature of phytotoxic 
substances  produced  during  plant  residue  decompo- 
sition  in soil. Phytopathology, 58 : 41-45. 
8-13. 
Retrue Ndmatol. 4 ( 2 ) :  209-212 


Accelerating the role of phenylalanine in shunting sex differentiation of Rotylenchulus reniformis by means of some nutrient formulae

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