International Research Journal of Plant Science (ISSN: 2141-5447) Vol. 4(9) pp. 272-274, October, 2013
DOI: http:/dx.doi.org/10.14303/irjps.2013.037
Available online http://www.interesjournals.org/IRJPS
Copyright © 2013 International Research Journals
Full Length Research Paper
Study on Residual Metabolite of Glomerella cingulata
from Raphia hookeri Seedling
Odigie E.E., *Eziashi E.I. and Chidi N.I.
Nigerian Institute for Oil Palm Research NIFOR), PMB 1030 Benin City, Edo state. Nigeria
*Corresponding Author`s Email: eziashius@yahoo.com
Abstract
An inhibitory effect of the residual metabolite extracted from the liquid culture of Glomerella
cingulata of Raphia hookeri seedling has been studied. The fungus filtrate of 500 mL was harvested
after 60 days of static incubation at 28 ºC of potato dextrose broth culture of the fungus and
concentrated to 50 ml. Leaves of Raphia hookeri and coconut palm were inoculated with Glomerella
cingulata residual metabolite and induced necrosis on both varieties. After thirty days of incubation
percentage of infection on Raphia hookeri palm was higher with 65.0% compared with 45.0% of
coconut palm. We suggest that the G. cingulata residual metabolite has phytotoxic potential,
because it causes necrosis on the leaves of R. hookeri and coconut seedlings.
Keywords: Glomerella cingulata, Residual metabolite, Raphia, Coconut.
INTRODUCTION
The major product of Raphia hookeri is palm wine. Wine
is tapped from a panel which consists of the base of short
spear leaves and the apical emerging terminal
inflorescence axis (Okolo, 2008). Glomerella cingulata
was found to be the causal organism of seedling blight of
Raphia hookeri (Oruade-Dimaro and Ekundayo, 1992).
Glomerella cingulata has been reported as mulberry
anthracnose fungus; the organism has been isolated from
leaf spot and blight symptoms on Kiwifruit (Ho, 2008).
Typical symptoms of most plant diseases revealed the
involvement of phytotoxic metabolites, which therefore
suggest a role for toxic metabolites, secreted by the
pathogen in the disease development. Metabolite of
many fungi may have adverse or stimulatory effects on
plants (Scheffer, 1983) such as suppression of seed
germination, malformation, and retardation of seedling
growth (Lynch and Clark, 1984). Neegaar (1977) reported
that some fungal pathogens often produce phytotoxins
that affect seed germination and seedling growth.
Pathogenic fungi and bacteria often damage their host
plants by producing toxins, which cause various
symptoms including necrosis, chlorosis, wilting, water
soaking and eventually the death of plants (Scheffer,
1983). Baker et al. (1997) reported that the virulence of
an organism is sometimes enhanced by its ability to
produce phytotoxins that kill cells in the tissue
surrounding the point of infection.
Toxins can be used for screening of resistance,
selection for resistance in tissue culture for which
resistant plants may be regenerated and genetically
engineered plants to destroy the toxic compound e.g.
genotypes of oats that were resistant to the victorin toxin
produced by Helminthosporium victoria were also
resistant to the fungus (Wheeler and Luke, 1955).
The objective of this study was to determine the effect
of residual metabolite of G. cingulata on the leaves of
Raphia hookeri and coconut seedlings with the view to
know whether it causes necrosis on both varieties.
MATERIALS AND METHODS
Diseased leaves of Glomerella cingulata causing
seedling blight were collected from Nigerian Institute for
Oil Palm Research (NIFOR) Raphia hookeri palm garden
into sterile Petri dishes. The samples were cut into 1mm2
under aseptic condition and grown in potato dextrose
agar (PDA) for seven days. The spores of isolated fungus
were re-infected on healthy Raphia hookeri leaf to
confirm pathogenesis. The re-isolated fungus was
identical to the initial inoculum.
After it, a small mycelia block (4mm) was removed
Odigie et al. 273
A
B
Figure 1. Light photographs of Raphia hookeri leaves. a) healthy and b)
blight infected seedling leaf by G. cingulata
C
D
Figure 2. Light photographs of Raphia and coconut leaves inoculated with
phytotoxic metabolite of G. cingulata. a) arrow head shows gradual invasion
from the mid rib of the leaf, b) invasion from the apex down to the stem, c)
complete invasion and dryness of Raphia seedling leaf from the apex down to
the base and d) arrow head shows gradual invasion from the mid rib of coconut
leaf
from 7-day-old pure culture of G. cingulata and
transferred to 1L conical flask containing potato dextrose
broth (PDB); it was aerobically and statically incubated at
28 ± 2°C for 60 days. The filtrates were harvested by
filtering through a muslin cloth twice and then by
Whatman filter papers No.1 twice. The culture filtrate was
centrifuged at 5000 x g for 15min, and the supernatant
500mL was concentrated to 50 mL residual metabolite
through lyophilization (Eziashi et al., 2007). The G.
Cingulata residual metabolite was spotted on each leaflet
of Raphia and coconut palms. Twenty seedlings for each
palm and the control were treated. The seedlings were
six months old at four leaves. The control treatments
were inoculated with sterile distilled water. They were
kept under well maintained garden for one month. Each
of the palms was replicated two times and experiment
repeated two times. The percentage of infected leaves
was calculated as the total leaves population sampled.
274 Int. Res. J. Plant Sci.
Table 1. Effect of residual metabolite of Glomerella cingulata on the leaves of Raphia and coconut
Incubation
period
(days)
Isolate
0
7
14
21
30
Control
G. cingulata
20
Sterile water
10
Sample Size
Raphia
Inf. Leaf
0.0
1.0
5.0
8.0
13.0
0.0
RESULTS AND DISCUSSION
Residual metabolite of Glomerella cingulata has shown
that it has the potential to induce symptoms of seedling
blight on healthy leaves of Raphia and coconut palms. G.
cingulata was isolated from naturally infected Raphia
hookeri seedling leaf showing symptom of seedling blight
(Figure 1b). On re-infected on healthy seedling leaves of
Raphia palm the re-isolated fungus was G. Cingulata
which showed symptoms of seedling blight. Susceptible
leaves of Raphia and coconut palms, symptoms
appeared 3 days after the inoculation of residual
metabolite of G. cingulata, It started as pin spot with grey
border, which expanded and caused necrosis on the
leaves fourteen days after inoculation (Figure 2a-2d). At
thirty days after inoculation complete invasion and
dryness of Raphia seedling leaf from the apex down to
the base (Figure 2c).
The percentage of infections after 7 days for Raphia
5.0% and coconut 0.0%, after 14 days 25.0% and 10.0%,
after 21 days 40.0% and 20.0% and after 30 days 65.0%
and 45.0% respectively (Table 1). The ability of G
cingulata to induce pin spot infection within 7 days after
inoculation provides supporting evidence that this
pathogen has the potential of phytotoxic metabolite. The
symptoms which include burnt-like appearance of the
infected leaves was an indication that phytotoxic
metabolite may be involved. Phytotoxins are important in
plant pathogenesis (Walton and Panaccione, 1993). The
necrotic action of the residual metabolite was more
evident on Raphia hookeri seedling as it expands more
when compared with coconut palm; this suggests that
Raphia hookeri is a natural habitat and host to G
cingulata. The control treatment remains healthy with
glossy appearance (Figure 1a). The effect of necrotic
actions on the leaflets and color pigmentation by G
cingulata in the broths’ appears to be associated with
metabolites produced which have toxic activities. This
% Inf.
Sample size
0.0
5.0
25.0
40.0
65.0
0.0
20
10
Coconut
Inf. Leaf
0.0
0.0
2.0
4.0
9.0
0.0
% Inf.
0.0
0.0
10.0
20.0
45.0
0.0
agrees with the hypothesis of Duarte and Archer (2003),
that isolate, which produced pigment in liquid culture, was
more efficient in producing a biologically active filtrate
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How to cite this article: Odigie E.E., Eziashi E.I. and Chidi N.I.
(2013). Study on Residual Metabolite of Glomerella cingulata from
Raphia hookeri Seedling. Int. Res. J. Plant Sci. 4(9):272-274