Morphological and allozyme variation in a collection of Lagenaria siceraria (Molina) Standl. from Côte d'Ivoire

Abstract

This study describes the intraspecific variation of 30 edible-seed Lagenaria siceraria germplasm accessions from the University of Abobo-Adjamé. These accessions were collected from three (Centre, East and South) geographical zones of Côte d’Ivoire. Selection based on seed size by the farmers has resulted in subdividing the species into two cultivars: large-seeded and smallseeded. The morphological diversity study of the collection included 18 accessions and 24 traits. The multivariate analysis of variance (MANOVA) showed a significant difference between the two groups of cultivars. Principal component analysis on 13 traits pointed out variations among individuals, mainly on the basis of flower, fruit, and seed size. Dendrogram with UPGMA method allowed clustering of the cultivars. The genetic structure analysis among accessions using allozyme markers showed the following values: 18.95% for the proportion of polymorphic loci (P), 1.21 for the number of alleles (A) and 0.053 for observed heterozygosity (Ho). The level of the within accessions genetic diversity (HS = 0.188) was higher than the genetic variation among accessions (DST = 0.082). The estimates of F-statistics indicated a low level of genetic differentiation between accessions (FST = 0.298). Such a value suggested that L. siceraria maintains about 30% of its genetic variation among accessions. Nei genetic distances between the two cultivars were also low (0.002), indicating that cultivars were genetically similar enough to belong to the same genetic group.

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S E Biotechnol. Agron. Soc. Environ. 2009 13(2), 257-270
Morphological and allozyme variation in a collection of
Lagenaria siceraria (Molina) Standl. from Côte d’Ivoire
Kévin K. Koffi (1), Guy K. Anzara (1), Marie Malice (2), Yao Djè (1), Pierre Bertin (3),
Jean-Pierre Baudoin (2), Irié A. Zoro Bi (1)
(1) Université d’Abobo-Adjamé. Unité de Formation et de Recherche des Sciences de la Nature. 02 BP 801. CI-Abidjan 02
(Côte d’Ivoire). E-mail: banhiakalou@yahoo.fr
(2) Gembloux Agricultural University – FUSAGx. Unité de Phytotechnie tropicale et Horticulture. Passage des Déportés, 2.
B-5030 Gembloux (Belgium).
(3) Université catholique de Louvain. Unité d’Écophysiologie et Amélioration végétale (ECAV). Croix du Sud, 2/11.
B-1348 Louvain-la-Neuve (Belgium).
Received on February 27, 2008, accepted on September 4, 2008.
This study describes the intraspecific variation of 30 edible-seed Lagenaria siceraria germplasm accessions from the University
of Abobo-Adjamé. These accessions were collected from three (Centre, East and South) geographical zones of Côte d’Ivoire.
Selection based on seed size by the farmers has resulted in subdividing the species into two cultivars: large-seeded and small-
seeded. The morphological diversity study of the collection included 18 accessions and 24 traits. The multivariate analysis
of variance (MANOVA) showed a significant difference between the two groups of cultivars. Principal component analysis
on 13 traits pointed out variations among individuals, mainly on the basis of flower, fruit, and seed size. Dendrogram with
UPGMA method allowed clustering of the cultivars. The genetic structure analysis among accessions using allozyme markers
showed the following values: 18.95% for the proportion of polymorphic loci (P), 1.21 for the number of alleles (A) and
0.053 for observed heterozygosity (Ho). The level of the within accessions genetic diversity (HS = 0.188) was higher than the
genetic variation among accessions (DST = 0.082). The estimates of F-statistics indicated a low level of genetic differentiation
between accessions (FST = 0.298). Such a value suggested that L. siceraria maintains about 30% of its genetic variation among
accessions. Nei genetic distances between the two cultivars were also low (0.002), indicating that cultivars were genetically
similar enough to belong to the same genetic group.
Keywords. Lagenaria siceraria, cucurbit, isozyme variation, morphological variation, cultivar, Côte d’Ivoire.
Variation morphologique et enzymatique dans une collection de Lagenaria siceraria (Molina) Standl. en Côte d’Ivoire.
Cette étude décrit la variabilité intraspécifique de 30 accessions de Lagenaria siceraria à graines consommées de la collection
de l’Université d’Abobo-Adjamé. Ces accessions proviennent de trois zones géographiques de la Côte d’Ivoire (Centre, Est
et Sud). La sélection opérée par les paysans sur la base de la taille des graines subdivise cette espèce en deux cultivars : le
cultivar à petites graines et le cultivar à grosses graines. Les études morphologiques impliquent 18 accessions et 24 caractères
morphologiques. L’analyse multivariée de variance (MANOVA) a montré une différence significative entre les deux cultivars.
L’analyse en composantes principales portant sur 13 caractères morphologiques a révélé une variation entre les individus
analysés, principalement sur base de la taille des fleurs, fruits et graines. Le dendrogramme construit avec la méthode UPGMA
a permis un regroupement des cultivars. L’analyse de la structure génétique basée sur les marqueurs allozymiques a donné les
valeurs suivantes : 18,95 % pour le pourcentage de loci polymorphes (P), 1,21 pour le nombre moyen d’allèles (A) et 0,053 pour
l’hétérozygotie observée (Ho). La diversité génétique intra-accession (HS = 0,188) est plus élevée que la diversité génétique
inter-accessions (DST = 0,082). Les estimations des F-statistiques indiquent un faible niveau de différentiation génétique entre
les accessions (FST = 0,298), suggérant seulement 30 % de variation entre les accessions. La distance génétique de Nei entre
les deux cultivars est également faible (0,002), indiquant que les deux cultivars sont génétiquement similaires et pourraient
appartenir au même groupe génétique.
Mots-clés. Lagenaria siceraria, cucurbites, variabilité enzymatique, variabilité morphologique, cultivar, Côte d’Ivoire.

258 Biotechnol. Agron. Soc. Environ. 2009 13(2), 257-270 Koffi K.K., Anzara G.K., Malice M. et al.
1. INTRODUCTION
Lagenaria siceraria (Molina) Standl. is an important
crop in tropical Africa. Some cultivars of this species
with others of the Cucurbitaceae family are called
Egusi in Benin, Nigeria, and pistachio in Côte d’Ivoire.
Although these crops are neglected and underutilized
in Africa, their cultivation is widespread in most West
African countries (Achu et al., 2005; Achigan-Dako
et al., 2006; Zoro Bi et al., 2006).
These cucurbits are prized for their oilseeds and
are consumed as soup thickener. Their seeds are
good sources of lipids and proteins (Achu et al.,
2005; Loukou et al., 2007). Like other neglected
and underutilized crops in Africa, cucurbits have
numerous agronomic and economic potentials.
They are well adapted to extremely divergent
agroecosystems and to various cropping systems.
They are also characterized by minimal inputs.
Increased production and use of these cucurbits can
result in food security and diversify small farmer’s
income (Chweya et al., 1999; Williams et al., 2002).
In developing countries, the exploitation of local
resources is certainly a way to achieve the objective
of food security, particularly for a fast-growing
population. However this requires the preservation
and availability of a high level of genetic diversity
of these resources (Given, 1987). This conservation
constitutes a challenge for crops such as cucurbits that
are endangered and have been neglected by national
research programs. To this regard prerequisite
information on genetic pattern is needed to make
appropriate decision.
In spite of the economic importance of edible
seeds of L. siceraria in Côte d’Ivoire, knowledge of
its genetic diversity and differentiation is very poor.
In order to fill up this gap, it is crucial to collect
the genetic resource available at country level and
to characterize the genetic diversity of the collected
accessions on the basis of several markers.
The objective of this study is to characterize
the collection of L. siceraria from different
geographical zones in Côte d’Ivoire and available
at Abobo-Adjamé University. The variability will
be assessed among accessions and cultivars, using
in particular morphological and enzyme markers. In
our investigations, we decided to use biochemical
markers, such as allozymes, because they are relevant
to identify the heterozygosity and to better know the
genetic structure of the species. Results obtained
from this characterization would contribute to
sample fruits and seeds in the most representative
areas, to conduct further molecular analysis and
to define appropriate sampling strategies for the
conservation of L. siceraria genetic resources in
Côte d’Ivoire.
2. MATERIAL AND METHODS
2.1. Plant material and collection sites
Thirty accessions (Table 1) of L. siceraria were
selected from the germplasm collection maintained
at the University of Abobo-Adjamé (Abidjan, Côte
d’Ivoire). An accession is a sample collected in one
field or obtained from one farmer’s stock. The selected
accessions were identified by alpha-numeric codes. A
minimum distance of 25 km separated two consecutive
collecting sites in each zone. The seed samples were
collected mainly in three geographical zones (South,
East, and Centre) of Côte d’Ivoire. The geographical
coordinates and ecological traits of sites of the collecting
missions are as follows (Zoro Bi et al., 2005):
– The southern zone which is localized between
latitudes 4°41 N-6°00 N and longitudes 4°00 W-
7°30 W. In this zone, rainfalls are abundant (annual
mean > 2,000 mm) and mean annual temperature
is 28°C, with annual amplitude of 5-10°C. Vegetation
is mainly represented by the tropical rain forest, with
mangrove on the coastal side.
- The eastern zone which is limited by latitudes
6°00 N-8°00 N and longitudes 3°00 W-5°00 W.
This zone is characterized by the transitional
woodland savannas, with several blocks of semi-
deciduous forests. Rainfalls vary from 875 to
1,910 mm, with an annual mean of 1,250 mm; the
annual mean temperature is 27°C.
- The central zone which is limited by latitudes
6°00 N-8°00 N and longitudes 5°00 W-7°00 W.
Annual rainfalls vary from 800 to 1,400 mm, with an
annual mean of 1,200 mm; the annual mean
temperature is 27°C. The vegetations are made of
various woodland savannas with extended ranges of
herbaceous areas.
Accessions used in this study are from two
landraces known as small-seed and large-seed. For
the morphological study 18 accessions with 12 small-
seeded and 6 large-seeded accessions were used. For
allozyme analysis, 13 small-seeded and 6 large-seeded
accessions were used. The number of seeds used
per accession for both morphological and allozyme
analysis are indicated in table 1.
2.2. Morphological characterization
Study site and experimental design. The study was
carried out in Abidjan district from May to November
2007. The experimental site was located in Akouedo
village in Abidjan suburb, between latitudes 5°17’N-
5°31’N and longitudes 3°45’W-4°22’W. In this zone,
rainfalls are abundant (annual mean > 2,000 mm) and
the mean temperature is 28°C, with annual amplitude of

Genetic diversity of Lagenaria siceraria 259
5-10°C. The field lay out was a completely randomized
design, with three replications. Each replicate consisted
of a 30 m x 27 m plot containing 90 plants (i.e., the
eighteen accessions), each accession being represented
by 5 plants. The planting distance was 3 m between
and within rows with 1.5 m of edges. Two consecutive
plots were spaced by 3 m. Manual weeding was carried
out during plant development.
Morphological data and analysis. Morphological
diversity was characterized using standard descriptors
for cucurbits: 24 characters were chosen among those
published for Citrullus lanatus (Thunb.) Matsum. &
Nakai (Maggs-Kölling et al., 2000) and Lagenaria
siceraria (Morimoto et al., 2005) (Table 2). Multi-
variate analysis of variance (MANOVA) was performed
with SAS software package (SAS, 1999) to investigate
the difference between the two cultivars. Principal
Components Analysis (PCA) with Statistica software
package (Statistica, 1995) was applied to further
describe morphological variation among accessions
and between cultivars. PCA is particularly relevant to
describe dataset by combining correlated variables into
factors. Prior to PCA, the average values of the traits
were standardized according to the formula:
standardized data =
This standardization is required to reach the same
scale for all the characters (Dagnelie, 1998). Data
were averaged across individuals for each accession,
and UPGMA (Unweighted Pair Group Method with
Arithmetic) dendrograms were computed by Statistica
Table 1. Passport data of accessions used for morphological and allozyme analysis of Lagenaria siceraria — Données
d’identification des accessions utilisées pour les analyses morphologiques et enzymatiques de Lagenaria siceraria.
Codes Cultivars Collection site Collection Geographic Sample size for Sample size
zone coordinates morphological for allozyme
analysis analysis
NI060a small seeds Assiè-Assasso East 6°39’N-4°11’W - 10
NI090b small seeds Assiè-Koumassi East 6°42’N-4°10’W 5 -
NI091b small seeds Assiè-Assasso East 6°39’N-4°11’W 5 -
NI106b large seeds Laviara Centre 7°00’N-6°30’W 5 -
NI109b small seeds Assiè-Assasso East 6°39’N-4°11’W 5 -
NI157a small seeds Assiè-Koumassi East 6°42’N-4°10’W - 10
NI174 small seeds Assiè-Assasso East 6°39’N-4°11’W 5 11
NI185 small seeds Agoua South 5°46’N-3°58’W 5 12
NI199b small seeds Ahouakoi South 5°46’N-3°55’W 5 -
NI200a small seeds Ahouakoi South 5°46’N-3°55’W - 10
NI210a small seeds Akin South 5°42’N-3°32’W - 6
NI215a small seeds Danguira South 5°39’N-3°45’W - 8
NI219b small seeds Danguira South 5°39’N-3°45’W 5 -
NI224b small seeds Abié South 5°49’N-3°56’W 5 -
NI227 small seeds Danguira South 5°39’N-3°45’W 5 17
NI228b small seeds Danguira South 5°39’N-3°45’W 5 -
NI239 small seeds Danguira South 5°39’N-3°45’W 10
NI241a small seeds Abié South 5°49’N-3°56’W - 10
NI248a small seeds Kodiossou South 5°45’N-3°46’W - 8
NI249 small seeds Danguira South 5°39’N-3°45’W 5 15
NI260b small seeds Kodioussou South 5°45’N-3°46’W 5 -
NI276 large seeds Bondoukou East 7°05’N-5°03’W 5 10
NI283b large seeds Koumala East 7°05’N-5°01’W 5 -
NI304 large seeds Laoudiba East 7°04’N-5°00’W 5 10
NI328a large seeds Kouassi N’Dawa Centre 7°00’N-6°33’W - 8
NI329a large seeds Kouassi N’Dawa Centre 7°00’N-6°33’W - 10
NI341b large seeds Flakiè East 7°07’N-5°02’W 5 -
NI347a large seeds Flakiè East 7°07’N-5°02’W - 12
NI354 large seeds Tefrôh East 7°05’N-5°02’W 5 11
NI388a small seeds Grand Alépé South 5°28’N-3°46’W - 12
a accessions used only for the analysis of allozymes — accessions utilisées uniquement pour les analyses enzymatiques; b accessions used
only for the analysis of morphological traits — accessions utilisées seulement pour l’analyse des caractères morphologiques; sample size
is the number of seeds sown per accession — la taille des échantillons est le nombre de graines semées par accession.
sample estimates-mean
standard deviation

260 Biotechnol. Agron. Soc. Environ. 2009 13(2), 257-270 Koffi K.K., Anzara G.K., Malice M. et al.
Table 2. List of descriptors used for characterization of Lagenaria siceraria germplasm and sample size (n) — Liste des descripteurs utilisés pour la caractérisation de
Lagenaria siceraria et taille des échantillons (n).
Characters Codes Type and period of observation Sample size (n)
Large seed Small seed
Emergence time (days)a ET Number of days from sowing to cotyledonary leaf opening 30 60
Tailspins time (days)a TT Number of days from sowing to first tailspin production 30 60
Male flowering time (days)a MF Number of days from sowing to first male flower opening per plant 30 60
Female flowering time (days)a FF Number of days from sowing to first female flower opening per plant 30 60
Male flower diameter (cm) MFD Diameter of petals, measured at flower opening 150 300
Female flower diameter (cm)b FFD Diameter of petals, measured at flower opening 150 300
Male flower peduncle length (cm)b MFPL Measured at flower opening 150 300
Female flower peduncle length (cm)b FFPL Measured at flower opening 150 300
Limb length (cm)b LL Measured after formation of the first fruit 150 300
Limb width (cm)b LWI Measured after formation of the first fruit 150 300
Plant length (m)a PL Measured 120 days after planting 30 60
Number of branchesa BN Total number of branches per plant at 120 days after planting 30 60
Days to fruit maturity (days)a FM Number of days from sowing to first mature fruit per plant 30 60
Number of fruits per planta FN Total number of fruits at plant maturity 30 60
Fruit weight (g)b FWE Weight of the mature fruits 150 300
Seed cavity diameter (cm)b SCD Measured on the mature fruits 150 300
Fruit width (cm)b FWI Measured on the mature fruits 150 300
Fruit length (cm)b FL Measured on the mature fruits 150 300
Number of seeds per fruitb NS Total number of seeds per fruit 150 300
Seed length (cm)c SL Measured after drying seeds to 5% moisture content 600 1,200
Seed width (cm)c SWI Measured after drying seeds to 5% moisture content 600 1,200
100-seeds weight (g) 100-SWE Weight of 100 seeds taken for a given individual after drying 2 to 3 1 to 2
seeds to 5% moisture content
Harvest indexa,d HI Measured after drying seeds to 5% moisture content per fruit 150 300
Tegument percent (%)c TP Measured after drying seeds to 5% moisture content 600 1,200
a measurement on each plant per cultivar — mesuré sur chaque plante par cultivar; b measurement on five organs per plant — mesuré sur cinq organes par plante; c measurement on
twenty seeds per fruit — mesuré sur vingt graines par fruit; d harvest index calculated as the ratio of grain yield to aboveground dry matter and the weight of the fruits — l’indice de
récolte est calculé en faisant le rapport du rendement en graine sur la matière sèche et le poids des fruits; n: number of measurements carried out for each trait — nombre de mesures
réalisées pour chaque caractère.

Genetic diversity of Lagenaria siceraria 261
software package (Statistica, 1995) to describe the
relationships between accessions. To determine
morphological differences among accessions from the
three zones of the collecting missions, multivariate
analysis of variance was carried out.
2.3. Allozyme analysis
Electrophoresis. Isozyme assays were conducted on
cotyledonary tissue. The selected seeds were sown in
field and cotyledons were taken from each 3-4 days old
seedling. A quantity of 0.01 g of cotyledonary tissue
from each seedling was ground in 0.045M TRIS-HCl,
pH 7.1 (Knerr et al., 1989; Staub et al., 1997). Plant
tissue was held at -20°C until the horizontal starch gel
electrophoresis was performed according to Zoro Bi
(1999).
Gels were prepared using 60 g of hydrolyzed
potato starch from Sigma (Sigma # S-5651) and 15 g
of sucrose that were dissolved in 600 ml of buffer. The
continuous morpholine-citrate, pH 6.1 was employed
for electrophoresis.
Four enzyme systems were used to study
electrophoretic variation: alcohol dehydrogenase
(ADH, E.C. 1.1.1.1), malate dehydrogenase (MDH,
E.C. 1.1.1.37), malic enzyme (ME, E.C. 1.11.1.7),
shikimate dehydrogenase (SKDH, E.C. 1.1.1.25).
The techniques for histochemical staining procedures
were those reported by Zoro Bi (1999) with Lima bean
(Phaseolus lunatus L.). For each enzymatic system, the
presumed loci were numbered in ascending order from
the anode. For each isozyme, the most common allele
was referred to as 100 and the other alleles were named
according to their migration distance in millimetres
using the standard (Koenig et al., 1989).
Data analysis. Allozyme data analysis was performed
using the computer program GENSURVEY (Vekemans
et al., 1997). Statistics of genetic diversity within and
among accessions were calculated: percentage of
polymorphic loci at 5% level (P), mean number of
alleles per locus (A), observed heterozygosity (Ho),
genetic diversity (He) corrected for small sample
size (Nei, 1978) and Wright’s F [F = (1-Ho/He)], the
inbreeding coefficient which measures the deviation
of the population genotypic composition from Hardy-
Weinberg (H-W) expectations. Deviation from Hardy-
Weinberg equilibrium at each locus in each accession
and heterogeneity in alleles frequencies among
accessions were tested by chi-square (χ2) using the
computer program GENEPOP (Raymond et al., 1995).
Genetic structure of the accessions was investigated
using Nei’s genetic diversity analysis on polymorphic
loci (Nei, 1973). The genetic differentiation among
accessions and cultivars was also estimated by
partitioning the total genetic diversity (HT) into gene
diversity within accessions or cultivars (HS) and among
accessions or cultivars (DST) i.e. HT = HS + DST. The
degree of genetic differentiation (GST) was calculated
as DST/HT. Wright’s fixation index within population
(FIS), among populations (FST) and total genetic
differentiation (FIT) were calculated to demonstrate the
relative distribution of genetic variation among and
within accessions and cultivars (Wright, 1965). The
number of migrants into accessions per generation (Nm)
was estimated (Wright, 1951). Cultivars divergence was
estimated using Nei’s genetic distance (Nei, 1978).
3. RESULTS
3.1. Morphological variation
Comparison of morphological traits using a multivariate
analysis of variance (MANOVA) showed a significant
difference between the two cultivars of L. siceraria
(F = 45.21; P < 0.001). As shown in table 3, this
difference is based on 16 traits: male flower diameter
(MFD), female flower diameter (FFD), female flower
peduncle length (FFLP), limb length (LL), limb width
(LWI), plant length (PL), number of branches (BN),
days to fruit maturity (FM), fruit weight (FWE), seed
cavity diameter (SCD), fruit width (FWI), fruit length
(FL), number of seed per fruit (NS), seed length (SL),
100-seeds weight (100-SWE), tegument percent (TP).
The large-seeded cultivar gave the highest values
for all these traits with the exception of the number
of branches from the central taproot (BN) and fruit
maturity (FM).
A minimum list of descriptors was selected from
the establishment of a correlations matrix (Table 4).
When we observed a high positive correlation (> 0.70)
between two variables, only one was retained to avoid
redundancy (Table 4). Consequently 13 variables:
seed emergence time (ET), days to the first tendril
appearance (TT), days to the first female flower (FF),
male flower diameter (MFD), female flower peduncle
length (FFPL), days to the first fruit maturity (FM),
fruit width (FWI), number of seeds per fruit (NS),
seed length (SL), seed width (SWI), 100-seeds weight
(100-SWE), harvest index (HI), and tegument percent
(TP) were used for the morphological characterization
of the accessions.
The first two principal components accounted for
46.398% of the total variability (eigenvalues > 1).
Male flower diameters (MFD), fruit width (FWI),
number of seeds (SN), 100-seeds weight (100-SWE)
are correlated with the first component (representing
32.762 % of the total variability). These variables are
negatively correlated with PC1. The second component
(13.636% of the variability) is mainly linked to the
seed emergence times (ET) with a positive correlation.

262 Biotechnol. Agron. Soc. Environ. 2009 13(2), 257-270 Koffi K.K., Anzara G.K., Malice M. et al.
Figure 1 shows the correlation circle of the two first
principal components analysis.
On the basis of these traits, two morphological
groups were formed (Figure 2). The group 1
included individuals from the small-seeded cultivar,
characterized by late maturity and small size of female
flower peduncle. The group 2 consisted of individuals
of large-seeded cultivar, characterized by large diameter
of petals opening, and heavy fruits of large sections
with many seeds per fruit.
UPGMA cluster analysis of morphological
differentiation among accessions computed from a
matrix of pairwise Euclidean distances showed two
distinct groups (Figure 3). Group 1 included all
accessions belonging to the large-seeded cultivar and
two accessions (NI174, NI091) from the small-seeded
cultivar. Group 2 included only accessions from the
small-seeded cultivar. Consequently, dendrogram
analysis showed that the two cultivars were
morphologically dissimilar since only two accessions
(11%) were inappropriately clustered.
The multivariate analysis of variance (MANOVA)
applied to the small-seeded cultivar obtained from the
South and East showed significant differences between
the two zones (F = 23.25; P < .001). This result is
mainly due to 10 characters out of 24 measured:
emergence time (ET), tailspins time (TT), male
flowering time (MF), female flowering time (FF), male
flower diameter (MFD), limb width (LWI), plant length
(PL), days to fruit maturity (FM), number of fruits per
plant (FN), seed cavity diameter (SCD) (Table 5). For
the large-seeded cultivar obtained from the Centre
and the East, the multivariate analysis also showed a
significant difference between the two areas (F = 21.88;
P < 0.001). This difference is due to 7 characters out of
the 24 measured: emergence time (ET), male flowering
time (MF), limb length (LL), limb width (LWI), days
to fruit maturity (FM), seed cavity diameter (SCD),
fruit width (FWI) (Table 5). These data suggest that
the morphological differences between accessions
belonging to the same cultivar but collected in distinct
geographical zones are not important.
3.2. Allozymes variation and genetic structure
Among the four enzyme systems investigated, Adh
revealed three loci with a total of four alleles, ME
showed only one locus with one allele, Mdh showed
two loci with three alleles and Skdh revealed one locus
with two alleles. Two loci (Adh-2 and ME) produced
Table 3. Values of twenty-four traits analyzed in two cultivars of Lagenaria siceraria and results of statistical tests — Valeurs
de vingt-quatre caractères analysés chez deux cultivars de Lagenaria siceraria et résultats des tests statistiques.
Characters Cultivars Parameters of statistical tests
Large seeds Small seeds F P
ET (d) 6.00 ± 1.14 5.86 ± 1.31 0.16 0.688
TT (d) 30.52 ± 7.25 30.34 ± 5.56 0.01 0.912
MF (d) 47.45 ± 12.75 48.59 ± 11.23 0.12 0.726
FF (d) 73.85 ± 8.92 71.14 ± 16.44 0.48 0.489
MFD (cm) 7.31 ± 0.54 5.61 ± 0.68 93.80 <0.001
FFD (cm) 6.52 ± 0.48 5.02 ± 0.49 123.64 <0.001
MFPL (cm) 19.98 ± 3.62 18.67 ± 3.28 1.41 0.240
FFPL (cm) 6.14 ± 0.99 5.01 ± 0.99 16.97 <0.001
LL (cm) 19.18 ± 2.11 12.05 ± 4.42 47.98 <0.001
LWI (cm) 16.68 ± 3.25 13.19 ± 2.42 21.37 <0.001
PL (m) 11.26 ± 3.48 5.98 ± 2.27 48.11 <0.001
BN 1.33 ± 0.57 2.61 ± 1.27 18.84 <0.001
FM (d) 128.71 ± 4.34 140.01 ± 9.41 26.78 <0.001
FN 5.00 ± 3.62 3.94 ± 2.60 1.63 0.207
FWE (g) 1497.46 ± 379.98 668.61 ± 300.91 82.74 <0.001
SCD (cm) 9.57 ± 1.33 7.94 ± 1.27 21.20 <0.001
FWI (cm) 13.64 ± 1.67 11.30 ± 1.06 41.62 <0.001
FL (cm) 17.62 ± 3.64 11.97 ± 1.76 62.23 <0.001
NS 319.66 ± 58.68 203.80 ± 51.68 60.32 <0.001
SL (cm) 1.96 ± 0.16 1.78 ± 0.11 26.61 <0.001
SWI (cm) 1.26 ± 2.08 0.72 ± 0.04 2.43 0.125
100-SWE (g) 20.42 ± 3.38 12.75 ± 1.79 56.26 <0.001
HI 0.04 ± 0.01 0.042 ± 0.01 0.04 0.848
TP (%) 37.36 ± 4.52 32.08 ± 3.58 23.53 <0.001
For the acronyms, see Table 2.

Genetic diversity of Lagenaria siceraria 263
Table 4. Correlations matrix between the twenty-four variables measured in two cultivars of Lagenaria siceraria — Matrice de corrélations des vingt-quatre variables
mesurées chez deux cultivars de Lagenaria siceraria.
Var. ET TT MF FF MFD FFD MFPL FFPL LL LWI PL BN FM FN FWE SCD FWI FL NS SL SWI 100- HI TP
SWE
ET 1.000 0.320 0.463 0.295 -0.062 0.058 -0.206 0.258 -0.040 0.198 -0.080 -0.202 0.019 -0.158 0.011 -0.264 -0.124 0.105 0.090 0.126 0.017 0.087 0.246 -0.208
TT 1.000 0.459 0.329 -0.013 0.701 -0.219 0.216 -0.019 -0.021 -0.013 -0.271 -0.129 -0.280 0.099 -0.158 0.046 0.240 0.103 -0.103 -0.087 0.154 -0.072 0.005
MF 1.000 0.721 -0.121 0.114 -0.229 0.279 -0.058 0.255 -0.215 -0.311 0.245 -0.319 -0.057 -0.323 -0.284 0.008 -0.101 -0.099 -0.043 0.050 0.249 -0.115
FF 1.000 -0.145 0.157 -0.134 0.337 0.041 0.138 -0.044 -0.222 0.081 -0.148 0.039 -0.242 -0.155 0.218 -0.065 0.027 0.069 -0.013 0.084 -0.213
MFD 1.000 0.422 0.477 0.345 0.763 0.704 0.446 -0.257 -0.260 0.245 0.462 0.403 0.442 0.417 0.482 0.463 0.109 0.440 -0.029 0.643
FFD 1.000 0.379 0.437 0.484 0.468 0.494 -0.484 -0.360 0.112 0.451 0.423 0.476 0.401 0.417 0.420 0.128 0.437 0.149 0.408
MFPL 1.000 0.754 0.487 0.497 0.479 -0.050 0.105 0.303 0.403 0.348 0.326 0.306 0.206 0.361 -0.105 0.305 -0.276 0.342
FFPL 1.000 0.439 0.284 0.416 -0.430 -0.519 0.039 0.419 0.269 0.395 0.430 0.444 0.413 0.146 0.409 0.178 0.215
LL 1.000 0.462 0.428 -0.374 -0.314 0.308 0.491 0.497 0.452 0.491 0.458 0.449 0.174 0.451 0.053 0.411
LWI 1.000 0.298 -0.273 0.129 0.228 0.322 0.020 0.088 0.322 0.300 0.378 -0.107 0.292 0.090 0.334
PL 1.000 -0.397 0.713 0.441 0.478 0.494 0.420 0.447 0.434 0.408 -0.003 0.418 -0.058 0.546
BN 1.000 0.756 -0.113 -0.282 -0.289 -0.318 -0.291 -0.309 -0.207 -0.133 -0.318 -0.159 -0.213
FM 1.000 0.095 -0.520 -0.285 -0.480 -0.474 -0.531 -0.440 -0.143 -0.402 0.078 -0.156
FN 1.000 0.163 0.327 0.795 0.060 0.271 0.189 -0.092 0.052 0.007 0.349
FWE 1.000 0.490 0.496 0.401 0.710 0.423 0.081 0.794 -0.239 0.481
SCD 1.000 0.429 0.395 0.449 0.721 0.110 0.435 -0.007 0.380
FWI 1.000 0.485 0.408 0.418 0.091 0.402 -0.091 0.377
FL 1.000 0.481 0.430 0.710 0.497 -0.183 0.353
NS 1.000 0.386 0.040 0.449 0.252 0.389
SL 1.000 0.292 0.413 -0.103 0.251
SWI 1.000 -0.007 -0.114 0.088
100-SWE 1.000 0.069 0.394
HI 1.000 -0.165
TP 1.000
Var.: variables; values of correlations in bold are significant — les corrélations significatives sont les valeurs en gras.
For the acronyms, see Table 2.

264 Biotechnol. Agron. Soc. Environ. 2009 13(2), 257-270 Koffi K.K., Anzara G.K., Malice M. et al.
Figure 1. Correlation circle of variables measured in the
two first principal components of the PCA — Cercle de
corrélation des variables mesurées chez les deux premières
composantes de l’ACP.
ET: seed emergence time — temps d’émergence des
graines; FF: days to the first female flower — nombre de
jours pour la floraison femelle; TT: days to the first tendril
appearance — nombre de jours pour l’apparition des
vrilles; HI: harvest index — indice de récolte; SN: number
of seeds — nombre de graines; 100-SWE: 100-seeds
weight — poids de 100 graines; SL: seed length — longueur
de la graine; SWI: seed width — largeur de la graine; MFD:
male flower diameter — diamètre de la fleur mâle; TP:
tegument percent — pourcentage de tégument; FM: days to fruit
maturity — nombre de jours de maturation des fruits; FFLP:
female flower peduncle length — longueur du pédoncule floral
femelle.
Component 2 (13.636%)
Component 1 (32.762%)
1
1
-1
-1
HI
FF
TT
ET
SN
SWI
100-SWE
SL
FM
FFPL
TP
MFD
2.5
1.5
0.5
- 2.5
- 1.5
- 0.5
Component 2 (13.636%)
Group II Group I
Component 1 (32.762%)
0 1 2 3-1-2-3
Figure 2. Accession distribution according to components
1 and 2 of the PCA based on morphological traits from
Lagenaria siceraria collection (L: large seed; S: small
seed) — Répartition des accessions suivant les axes 1 et 2 de
l’ACP sur base des traits morphologiques de la collection de
Lagenaria siceraria (L : grosse graine ; S : petite graine).
350 300 250 200 150 100 50 0
Group II
Group I
NI 354 L
NI 283 L
NI 106 L
NI 174 S
NI 276 L
NI 304 L
NI 091 S
NI 090 S
NI 109 S
NI 185 S
NI 224 S
NI 219 S
NI 228 S
NI 249 S
NI 227 S
NI 260 S
NI 199 S
NI 341 L
Figure 3. Dendrogram illustrating morphological similarities among 18 accessions (L: large seed; S: small seed) from
Lagenaria siceraria collection — Dendrogramme illustrant la similarité morphologique de 18 accessions (L : grosse graine ;
S : petite graine) de la collection de Lagenaria siceraria.

Genetic diversity of Lagenaria siceraria 265
Table 5. Values of twenty-four traits analyzed in two Lagenaria siceraria cultivars from different geographical zones and results of statistical tests — Valeurs de vingt-
quatre caractères analysés chez deux cultivars de Lagenaria siceraria issus de différentes zones geographiques et résultats des tests statistiques.
Characters Cultivar with small seeds Parameters of statistical tests Cultivar with large seeds Parameters of statistical tests
Zone East Zone South F P Zone East Zone Centre F P
ET (d) 6.60 ± 1.59 5.33 ± 0.73 10.32 0.003 5.666 ± 0.840 8.000 ± 0.000 22.170 <0.001
TT (d) 33.00 ± 7.05 28.43 ± 3.20 6.89 0.013 29.858 ± 7.650 34.533 ± 1.514 1.070 0.314
MF (d) 55.05 ± 14.83 43.97 ± 3.65 10.91 0.002 44.388 ± 10.691 65.800 ± 8.146 10.790 0.004
FF (d) 79.43 ± 21.10 65.21 ± 8.54 7.81 0.008 73.029 ± 7.257 78.80 ± 17.446 1.080 0.31
MFD (cm) 5.02 ± 0.57 6.03 ± 0.38 40.39 <0.001 7.254 ± 0.562 7.64 ± 0.295 1.310 0.267
FFD (cm) 4.89 ± 0.58 5.12 ± 0.40 2.17 0.150 6.483 ± 0.471 6.786 ± 0.589 1.010 0.328
MFPL (cm) 18.760 ± 3.15 18.95 ± 3.45 0.03 0.868 19.583 ± 3.213 22.366 ± 5.583 1.56 0.226
FFPL (cm) 6.18 ± 1.18 6.11 ± 0.87 0.04 0.848 5.094 ± 1.003 4.53 ± 1.006 0.80 0.381
LL (cm) 11.05 ± 6.68 12.76 ± 1.27 1.33 0.256 19.594 ± 1.989 16.706 ± 0.503 6.010 0.024
LWI (cm) 11.93 ± 2.96 14.08 ± 1.42 8.39 0.006 15.732 ± 2.375 22.366 ± 0.952 22.000 <0.001
PL (m) 4.59 ± 1.56 6.97 ± 2.20 12.77 0.001 11.672 ± 3.577 8.766 ± 1.101 1.870 0.186
BN 2.47 ± 1.12 2.71 ± 1.38 33.000 0.572 1.388 ± 0.607 1.000 ± 0.000 1.180 0.291
FM (d) 133.53 ±10.65 144.63 ± 4.66 18.11 <0.001 127.000 ± 0.000 138.955 ± 2.114 780.690 <0.001
FN 2.20 ± 0.56 5.19 ± 2.77 16.88 <0.001 5.222 ± 3.843 3.666 ± 1.527 0.46 0.504
FWE (g) 656.16 ± 425.34 677.50 ± 177.82 0.04 0.837 1,488.760 ± 389.557 1,549.666 ± 386.174 0.06 0.804
SCD (cm) 7.41 ± 0.88 8.30 ± 1.39 4.71 0.037 9.974 ± 0.955 7.166 ± 0.152 24.740 <0.001
FWI (cm) 11.07 ± 1.14 11.46 ± 0.99 1.23 0.274 13.997 ± 1.525 11.478 ± 0.320 7.790 0.011
FL (cm) 12.36 ± 2.19 11.69 ± 1.36 1.27 0.268 17.646 ± 2.347 17.430 ± 9.252 0.01 0.927
NS 213.87 ±58.07 196.57 ± 46.73 0.98 0.329 321.518 ± 61.595 308.516 ± 44.418 0.12 0.732
SL (cm) 1.77 ± 0.09 1.78 ± 0.12 0.12 0.726 1.966 ± 0.171 1.942 ± 0.093 0.06 0.816
SWI (cm) 0.72 ± 0.04 0.72 ± 0.05 0.001 0.93 1.328 ± 2.24 0.859 ± 0.081 0.12 0.271
100-SWE (g) 12.62 ± 2.28 12.84 ± 1.39 0.13 0.720 21.443 ± 7.032 20.923 ± 2.154 0.02 0.902
HI 0.05 ± 0.02 0.03 ± 0.01 2.72 0.108 0.043 ± 0.010 0.039 ± 0.008 0.500 0.489
TP (%) 30.22 ± 3.57 33.45 ± 2.94 8.83 0.054 36.794 ± 4.684 41.106 ± 0.910 2.42 0.136
For the acronyms, see Table 2.

266 Biotechnol. Agron. Soc. Environ. 2009 13(2), 257-270 Koffi K.K., Anzara G.K., Malice M. et al.
unclear patterns and were discarded. Thus five loci were
taken into account for further analysis. Two loci were
polymorphic and diallelic: Mdh-2 and Skdh, whereas
Mdh-1, Adh-1 and Adh-3 were monomorphic.
The proportion of polymorphic loci per accession
(P) varied from 0 (e.g., NI060) to 40% (e.g., NI388)
with a mean of 18.95%. The mean number of alleles
(A) per locus varied from 1.0 (e.g., NI210) to 1.4 (e.g.,
NI248) with an average of 1.2, indicating a low allelic
richness. A low genetic diversity was also observed.
Indeed, the average observed heterozygosity was 0.053
ranging from 0 (e.g., NI249) to 1.4 (e.g., NI241) and
the average expected heterozygosity (He) was 0.073
ranging from 0 (e.g., NI329) to 0.202 (e.g., NI276).
The observed mean heterozygosity (Ho = 0.053)
was similar to the average expected heterozygosity.
This suggested that the populations were at Hardy-
Weinberg equilibrium. According to the Chi-square
test, 66.67% of the accessions were not significantly
different from zero (α = 0.05) confirming the Hardy-
Weinberg equilibrium hypothesis. This indicated that
most accessions did not deviate from random union of
gametes.
The total gene diversity (HT) was 0.270 (Table 6).
For Mdh-2 locus, the largest proportion of diversity
was attributable to the within-accessions component
(HS = 0.243; DST = 0.022). However, for Skdh locus,
difference between the within accessions and the
among accessions components of diversity (HS = 0.133;
DST = 0.141) was not significant. On the other hand,
the coefficient of gene differentiation (GST) between
accessions was estimated at 29.8%, indicating that most
of the total genetic diversity in this species was within
accessions rather than among accessions. From table 6,
the mean inbreeding index (FIT) for the 19 accessions
was 0.505. This relatively high value showed important
deficiency in heterozygosity. The average FIS of 0.306
indicated a slight deficit of heterozygotes within
accessions. On the other hand, the average FST of 0.299
showed a low genetic differentiation among accessions.
The mean number of migrants per generation (Nm)
based on Wright’s equation was 0.963. Such a value
indicated that on average, one individual migrated in a
given accession (seed stock or field) per generation.
At the cultivar level (Table 7), the average of total
gene diversity (HT) and intra-cultivar genetic diversity
(HS) were 0.300 and 0.298, respectively. The inter-
cultivar genetic diversity (DST) and the coefficient of
gene differentiation among cultivars (GST) were 0.002
and 0.007 respectively. According to these results, the
degree of genetic differentiation between cultivars was
very low (only 0.7%). F-statistics for the two cultivars
indicated a relatively high mean inbreeding index
(FIT = 0.569), showing an important deficiency in
heterozygosity. A high value was also obtained for FIS
(0.567). The proportion of the total genetic diversity
among cultivars (FST = 0.006) was very low. A low
value was also estimated for Nei genetic distances
between the two cultivars, with D = 0.002, indicating
that cultivars were genetically similar enough to
belong to the same genetic group.
4. DISCUSSION
4.1. Morphological variation
Our study showed morphological heterogeneity
within the collection of L. siceraria of Abobo-
Adjamé University in Côte d’Ivoire. According to
the multivariate analysis of variance, difference
between the two groups of accessions with small
and large seeds size was significant. Fruit and seed
shape and size are reported to be highly variable in
the genus Lagenaria (Bisognin, 2002). In most rural
African communities, the landraces of L. siceraria are
generally distinguished by their fruit size and shape,
and designated by common name according to these
Table 6. Genetic diversity, F-statistics and estimates of gene flow between 19 Lagenaria siceraria accessions — Diversité
génétique, F-statistiques et estimation du flux de gènes entre 19 accessions de Lagenaria siceraria.
Locus Nei genetic diversity indices F-statistics Gene flow
HT HS DST GST FIT FIS FST Nm
Mdh-2 0.265 0.243 0.022 0.082 0.331 0.272 0.082 0.997
Skdh 0.274 0.133 0.141 0.514 0.680 0.340 0.515 0.928
Mean 0.270 0.188 0.082 0.298 0.505 0.306 0.299 0.963
Std 0.006 0.078 0.084 0.305 0.247 0.048 0.306 0.049
HT: the total genetic diversity — la diversité génétique totale; HS: the genetic diversity within accessions — la diversité génétique
intra-accession; DST: the genetic diversity among accessions — la diversité génétique inter-accessions; GST: the among accessions gene
differentiation coefficient — coefficient de différenciation génétique inter-accessions; FIT: the mean inbreeding coefficient of a set of
accessions — le coefficient moyen de consanguinité de l’ensemble des accessions; FIS: the fixation index related to non-random mating
within populations — l’indice de fixation relatif au croisement non au hasard au sein des populations; FST: the among accessions genetic
differentiation due to genetic drift — la différenciation génétique inter-accessions due à la dérive génétique; Nm: the gene flow estimate
according to Wright’s (1951) equation — le flux de gène selon l’équation de Wright’s (1951); Std: the standard error — l’écart-type.

Genetic diversity of Lagenaria siceraria 267
morphological differences (Morimoto et al., 2005).
In Côte d’Ivoire, farmers refer to seed size when
designating cultivars of edible-seeded L. siceraria
(Zoro Bi et al., 2006). Also, in the cucurbit family,
the significant contribution of fruit and seed traits
to morphological variability has been reported for
watermelon (Maggs-Kölling et al., 2000; Gusmini,
2003), bottle gourd (Morimoto et al., 2005) and
squash (Paris, 2001).
However, in estimating the relative contribution
of the different traits in the overall phenotypic
variation among the 18 accessions, the first two
principal components (PCs) explained 46.398% of
the diversity obtained from the 13 selected traits. The
variability explained by the first PC alone (32.762%)
was mainly due to variations in fruit (FWI), seed
(NS, 100-SWE) and flower sizes (MFD). In the
cucurbit family, the significant contribution of fruit
and seed traits to morphological variability has been
reported for watermelon (Maggs-Kölling et al., 2000;
Gusmini, 2003). In spite of a variability explained by
the first two principal components inferior to 50%,
a relative separation was observed between the two
cultivars (Figure 2). The presence of one individual
(NI276-L5) from the large seeded accession (NI276)
in the group 1 made up of small-seeded accessions
could result from accidental mixture by farmers or
collectors. However Morimoto et al. (2005) reported
the difficulty to classify the landraces of L. siceraria
into distinct groups, because of the high and
continuous morphological variation in the species.
The difference between the two studies results from
the fact that we analyze only two edible-seed cultivars
while Morimoto et al. (2005) analyzed several forms
of L. siceraria and its wild relatives.
A strong positive correlation between the weight of
the fruits and the number of seeds was observed in our
study. The same positive correlation was also noted
in watermelon (Nerson, 2002). Therefore the fruit
weight of L. siceraria could be used as a good criteria
to select individuals with higher number of seeds. This
result is congruent with findings of Achigan-Dako
et al. (2006).
The phenotypical variation between the two
cultivars of L. siceraria from Côte d’Ivoire seemed to
be uncorrelated to the different regions where samples
were collected. Two hypotheses could explain such a
result:
– the occurrence of an important seed flow,
– the similarity of the cultivation history among the
collecting zones.
According to Montes-Hernandez et al. (2002),
human activities significantly buffer genetic variability
between plants occurring in different geographical
regions. This argument could be supported by the
fact that most often farmers exchange seeds among
themselves. Fruits and seeds are selected to constitute
planting material for the next season. In addition, parts
of the harvested products are marketed and contribute
to the movement of seeds between regions.
4.2. Genetic diversity
In general, the intra-accession polymorphism indices
estimated in this study were low (P = 18.95%; A = 1.21;
He = 0.073). These indices are similar to those
reported by Decker-Walters et al. (1990) on Cucurbita
maxima Duchesne (P = 11.5%; A = 1.43; He = 0.039)
and on Cucurbita pepo L. (P = 19.3%; A = 2.24;
He = 0.068). However values from L. siceraria were
smaller than those calculated in four Cucurbita taxa
by Montes-Hernandez et al. (2002): P = 100%;
A = 2.08; He = 0.407 for Cucurbita argyrosperma
ssp. sororia Huber, P = 93%; A = 2.5; He = 0.391
for Cucurbita argyrosperma ssp. Argyrosperma Hort
Huber, P = 97%; A = 2.06; He = 0.496 for Cucurbita
moschata Duchesne and P = 92%; A = 2.08; He =
0.366 for C. pepo. The lack of RAPD diversity (known
to be highly polymorphic) was also found in southern
African landraces of L. siceraria (Decker-Walters
et al., 2001) and in several accessions of two Citrullus
species: Citrullus lanatus and Citrullus colocynthis
(L.) Schrad. (Levi et al., 2001). These results confirm
our study and pointed out a narrow genetic basis in this
species.
In spite of the very low number of loci and
individuals analyzed in this study, two hypotheses could
explain the low allelic richness: the selection favouring
homozygote individuals and the founder effect.
Table 7. Genetic diversity, F-statistics at polymorphic loci of two Lagenaria siceraria cultivars — Diversité génétique, F-
statistiques aux loci polymorphes de deux cultivars de Lagenaria siceraria.
Locus Nei genetic diversity indices F-statistics
HT HS DST GST FIT FIS FST
Mdh-2 0.291 0.290 0.001 0.003 0.477 0.479 0.003
Skdh 0.309 0.304 0.003 0.009 0.661 0.655 0.009
Mean 0.300 0.298 0.002 0.007 0.569 0.567 0.006
Std 0.013 0.010 0.001 0.004 0.130 0.124 0.004

268 Biotechnol. Agron. Soc. Environ. 2009 13(2), 257-270 Koffi K.K., Anzara G.K., Malice M. et al.
However, the reproductive biology of indigeneous
cucurbit avoiding selfing makes the first hypothesis
(homozygotes selection) improbable. Indeed,
L. siceraria is monoecious (staminate and pistilate
flowers are separated) and flowers are pollinated by
various insects. Thus this species is bound to experiment
insect-mediated cross pollination which promotes
random-mating, buffering homozygotes selection
(Wright, 1951). This argument was supported by the
high percentage of accessions (66.67%) not significantly
different from Hardy-Weinberg equilibrium. The last
hypothesis: the founder effect, due to farmer’s seeds
selection approach, is most likely the major cause of
the low allelic richness. In particular, in the collecting
sites, generally a low number of seeds is usually taken
from the farmer’s stock, or are obtained from local
markets, resulting to the genetic variability depletion
(Nei et al., 1975).
In our study, trends of variation were not similar with
the application of the two markers: morphology and
allozymes. Differentiation among cultivars was much
higher for morphological traits than for allozymes. Djè
et al. (1998) found similar results for sorghum landraces
of northwestern Morocco. During the selection process,
farmers and breeders favour phenotypic diversity, in
order to meet varietal adaptation to diverse cropping
systems and consumer’s requirements. Considering
the low genetic variability observed in our L. siceraria
collection, one can assume that allozyme markers were
not powerful enough to capture the genetic basis of
the morphological variation, probably due to complex
and multigenic inheritance of fruit and seed traits in
cucurbits (Guner et al., 2004).
4.3. Genetic structure and gene flow
The mean within-accession gene diversity index
(HS = 0.188) was similar to those reported by Hamrick
et al. (1997) for cross-pollinated plants. Indeed, these
authors showed that intra-population gene diversity
index varied between 0.103 and 0.266. The degree of
genetic differentiation between accessions (GST = 0.298)
was also similar to those reported for many cross-
pollinated plants, GST = 0.234 (Hamrick et al., 1997).
The low values of GST in the present study could result
from the high level of gene flow among accessions, in
particular the frequent seed exchange among farmers.
However, our GST value was lower than the value
estimated in Schizopepon bryoniaefolius Maxim.
(GST = 0.68), a wild Cucurbitaceae (Akimoto et al.,
1999). Differences between our study and Akimoto
et al. (1999) study could be attributed to the different
floral biology between the two species. L. siceraria is
monoecious (male and female flowers are separated)
and predisposed to predominantly outcrossing, while
S. bryoniaefolius is androdioecious (with herma-
phrodite flowers) which favours selfcrossing.
On average, FIS showed a significant deficiency
of heterozygosity (FIS > 0) for all accessions. The
proportion of the total genetic diversity found among
accessions (FST = 0.299) was higher than that described
by Hamrick et al. (1989) in animal-pollinated species
(FST = 0.187), and almost similar to the larger group
including the cross-pollinated plants (FST = 0.234). The
gene flow estimation (Nm = 0.963) and the low genetic
differentiation between accessions (FST = 0.299)
confirmed the high rate of gene exchange between
accessions.
5. CONCLUSION
This study has allowed a better knowledge of the
cultivated L. siceraria collection of the University
of Abobo-Adjamé (Abidjan, Côte d’Ivoire).
Morphological characterization showed significant
difference between two cultivars: small-seeded and
large-seeded cultivars. Isozyme electrophoresis
data indicated a lower genetic heterogeneity among
accessions than within accessions. Therefore, during
the collecting missions, it is recommended to collect
a sufficient number of seeds or fruits within each
accession, which is better than attempting to collect as
many accessions as possible. However the low number
of analyzed loci and individuals suggest that analysis
of additional accessions is required before a definitive
conclusion can be performed. On the other hand,
many questions still remain to be solved. An in-depth
knowledge of reproductive biology of this species and
the use of DNA markers are required. Indeed, molecular
markers can be an effective means to determine genetic
relatedness among cultivars and among accessions
present in L. siceraria germplasm collection. These
markers are generally more polymorphic than
isozymes. Results obtained in studying floral biology
and molecular variability will help us to define
sampling strategies and optimum sample size for the
management of L. siceraria genetic resources.
Acknowledgements
This research was financed by the « Direction Générale
de la Coopération au Développement » (DGCD, Brussels,
Belgium) and supervised by the « Commission Universitaire
pour le Développement » (CUD, Brussels, Belgium).
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