SCREENING OF TOMATO ACCESSIONS FOR RESISTANCE TO ...

SCREENING OF TOMATO ACCESSIONS FOR RESISTANCE TO FUSARIUM WILT
CAUSED BY Fusarium oxysporumj.sp. Iycopersici IN SOUTHWEST Nigeria
A PROJECT SUBMITTED TO THE, DEPARTMENT OF CROP PROTECTION,
COLLEGE OF PLANT SCIENCE AND CROP PRODUCTION UNIVERSITY OF .
AGRICULTURE, ABEOKUTA, OGUN STATE, NIGERIA.
IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF
BACHELOR OF AGRICULTURE (B.AGIUC), OF THE UNIVERSITY OF
AGRICULTURE, OGUNSTATE, NIGERIA.

DEDICATION
This project is dedicated to God Almighty, who has been my strength and helper throughout
my
undergraduate
days in UNAAB.

My gratitude goes to our Lord Jesus Christ, the greatest provider, sustenance and giver of
peace.
My parents; Mr and Mrs. Oduyeru, I really appreciate you for your support, morally and
financially,
may you live long to eat the fiVit of your labour in Jesus name, Amen. My siblings
Miss Temitope, Damilola, Busola, BiodUIl: and Segun, My Daddy (Mr Wale LawaI) for your
fatherly support and Advice and my Big Uncles; Mr Deji Lawal, Mr Ranti Oduyeru and Mr
Gboyega Okubanjo thanks for your understanding
at all time.Also, to all_my immediate relatives,
thanks for your support. We shall all live to see more of His goodness.
To my supervisor: Dr. A.R Popoola, .thank you for your fatherly advice and for all the
knowledge
you imparted in me. I am really grateful. And not forgetting Mr. Ganiyu for your
Advice and moral support throughout this project
To my Head of Department;
Dr Pitafi And to my lecturers, Dr. Atugun, Mr. Odeyemi, Dr.
Ayo-John and Dr. Afolabi and to others that their names are not mentioned here, thank you sirs.
To my project mates, in person of Lekan Davies, Kuponiyi Razak and Bimbola Adefolalu., God
bless you all for your kind gesture all thr01,lgh. And not forgetting my friend and a brother from
another mother in person of Adami Ayokunle, thanks a million. May our labour never be in vain.

The experiment
was conducted to investigate the resistant level of tomato accessions to Fusarium
wilt caused by Fusarium oxysporum f sp.Lycopersici. The experiment was a randomized
complete block design (RCBD) consisting of 3 treatments with 3 replicates. Ten accessions were
inoculated with samples of fungal strain 1 and strain 2 using Drenching method into the soil.
Plant performance
was based on plant height, number of leaves number of branches and number
of tomato fruits. Disease assessment was based on disease severity, incidence and number of
days for 50% wilt. The result obtained from the experiment shows that different variety has
different resistant level to the disease which was evident in the plant height and number of fruits
produced.NG/MRIMA Y/09/006 is resistant to strain 1 and susceptible to strain 2 of the Fusarium
been inoculated into it and was able to produce the high number of fruits.
This study could therefore suggest N GIM RIMA Y109/006 which has minimum mean severity
(36.03%) and could produce reasonable number of fruit under the Fusarium wilt infection.

1.0 Introduction
1.1 Tomato
1.2 Botanical description
1.3 Disease resistance
1.4 Abiotic stress tolerance
1.5 Objective
1.6 Justification

1: Disease Severity scale
2: Disease assessment oftomato accessions under infection and control
3: Growth performance of tomato accessions.
4: Yield parameter of Tomato accessions

Tomato (Lycopersicon escuientum Mill) is an important source of vitamin C,
calories, phosphorus and calcium (Davis and Hobson, 1981; Langer and Hill, 1991).Worldwide,
tomatoes are an important part of a diverse and balanced diet (Willcox et ai., 2003). It is estimated
that over 62 800 accessions of the cultivated and wild species of tomato (mostly L. escuientum
accessions) are maintained in genebanks around the world(Rossi et ai., 1998), Among the nine
Lycopersicon species, only" L. escuientum has become a domesticated crop though L.
pimpinellifolium (with fruit diameter -1 cm) is also casually planted for consumption(Rick,
1978).The cultivated tomato has limited variability, largely because of several population
bottlenecks in the forms of founder events and natural and artificial selections that occurred during
domestication and evolution of modem cultivars(Rick, 1976),During the past 70 years wild species
of tomato have been utilized in breeding programs to improve the cultivated tomato (Rick,.
1979;.Rick, 1982), According tos (Rick, 1976), domestication of L. escuientum
was accompanied
by a transition from exerted to inserted stigmas, and consequently changing from facultative
outcrossing to enforced inbreeding, It is not known exactly -when domestication of tomatoes
occurred, however, by the time the Spanish conquered Mexico in 1523, they were already
domesticated (Rick, 1978).

1.2 Botanical description
Tomato belongs to the nightshade family Solanaceae, which is in division
Magnoliophyta, class Magnoliopsida, subclass Asteridae, order Solanales, and suborder Solanineae
(Knapp et al., 2004; Nee et al., 1991.). The extremely diverse and large Solanaceae family is
believed to consist of 96 genera and over 2800 species in three subfamilies, Solanoideae (in which
Lycopersicon belongs), Cestroideae, and Solanineae. Solanaceae is one of the most economically
important families of angiosperms and contains many of the commonly ~ultivated plants, including
potato, tomato, pepper, eggplant, petunia, and tobacco. This family is the most variable of all crop
species in terms of agricultural utility, the 3rd most economically important crop family, exceeded
only by the grasses and legumes, and the most valuable in terms of vegetable crops (Vander
Hoeven, et al., 2002). Among all plant families, members of the Solanaceae are extremely diverse in
terms of growth habit (from trees to small annual herbs), habitat (from deserts to the wettest tropical
rain forest), and morphology (Knapp et al., 2004). Many Solanaceous species have played important
roles as model plants, including tomato, potato, pepper, tobacco, and petunia. The tomato genus
Lycopersicon is one of the smallest genera in Solanaceae, though the centerpiece in the family for
genetic and molecular research. It is the closest to the genus Solanum (nightshade), an association
which originally led people to believe tomato was poisonous (Rick, 1978). The cultivated tomato
was originally named Solanum Iycopersicum by Linnaeus.(Linnaeus, 1953).
Tomato is susceptible to over 200 diseases caused by pathogenic fungi, bacteria,
viruses, or nematodes (Lukyanenko, 1991). Without question, the greatest contribution of modem
plant breeding to tomato improvement has been through development of cultivars with improved
disease resistance. Resistance has been identified, and in many cases characterized, for more than 30

of the major tomato diseases. Most commercial cultivars possess up to 6 (in true breeding lines) or
10 (in hybrids) disease-resistance attributes. These mainly include diseases for which major
resistance genes have been identified, including fusarium wilt, verticillium wilt, root-knot nematode,
alternaria stem canker, gray leaf spot, and some bacterial and viral diseases. However, horizontal
(a.k.a. field or polygenic) resistance has also been reported for several tomato diseases, where major
genes for resistance to a particular pathogen or race are not found, such as early blight, powdery
mildew, bacterial canker, and bacterial wilt. Except in a few cases, tomato wild species have been
utilized as the source of resistance for all tomato diseases. Resistance resources have been identified
in most related wild species of tomato, in particular 1. pimpinellifolium, 1. peruvianum, and 1.
hirsutum. For some tomato diseases, such as late blight (caused by oomycete Phytophthora
infestans) and powdery mildew (caused by fungus Oidium lycopersicum), both vertical and
horizontal resistances have been identified.
Although the cultivated tomato is widely adapted to different climates, its growth and
development is rather sensitive to different environmental stresses, including salinity, drought,
excessive moisture, extreme temperatures, mineral toxicity and deficiency, and environmental
pollution. There is limited genetic variation for abiotic stress tolerance within the cultivated species
and most commercial cultivars are considered moderately to highly sensitive to different stresses.
Fortunately, sources of genetic tolerance (or resistance) to different abiotic stresses are found within
the related wild species, including 1. chilense, 1. peruvianum, 1. pennellii, 1. pimpinellifolium, 1.
hirsutum,1. cheesmanii, 1. chmielewskii, and 1. parviflorum (Foolad, 2005). In addition, there are a
few species within Solanum that exhibit tolerance to environmental stresses and which may be
utilized in tomato breeding for stress tolerance. Several tomato wild species have been utilized for

genetic and physiological characterization of abiotic stress tolerance and for breeding purposes
(Scott, 1993), In addition, stress tolerance is a developmentally regulated, stage-specific
phenomenon; tolerance at one stage of plant development is often not correlated with tolerance at
other developmental stages (Asins et al., 1993; Foolad, 1999).
1.5 Objective:
To determine the resistance levels of different tomato varieties to Fusarium wilt
disease caused by Fusarium oxysporum f
sp. Iycopersici.
1.6 Justification:
Tomato varieties are susceptible to several diseases caused by pathogenic fungi,
bacteria or viruses. Different c?ntributions of modem plant breeding to tomato improvement have
been through development of cultivars with improved disease resistance. Hence the need to
determine the resistance level of different varieties of tomato to Fusarium caused by Fusarium
oxysporumfsp
lycopersici wilt disease in South West Nigeria.

· .
plant roots, but seem not to invade the vascular system (Olivain and Alabouvette 1997, 1999). The

However, there are indications for a certain F: oxysporum-strain
specific effect of compounds
found in tomato root exudates. In a recent study it was reported that the germination rate of several
F. oxysporum strains is affected differently by tomato root exudates (Steinkellner et al., 2005).
Moreover, studying the spore germination of a Fori strain and a biocontrol strain of F. oxysporum in
tomato root exudates and two of its major known compounds, glucose and citric acid, (Bolwerk et
al., 2005) found a higher stimulation for the biocontrol strain than for the pathogenic strain. In
several studies it has been shown that root colonisation by symbiotic arbuscular-mycorrhizal fungi
alters the root exudation pattern and thus the effect of the exudates on soil-inhabiting microbes
(Lioussanne et al., 2003; Pinior et al., 1999; Sood, 2003). (Pinior et al., 1999) reported that root
exudates from mycorrhizal plants affect the hyphal growth of arbuscular mycorrhizal fungi
differently, compared to root exudates from non-mycorrhizal plants. Recently, (SchefIknecht et al.,
2006, 2007) reported that root colonisation by an arbuscular-mycorrhizal fungus also affects the
microconidial germination of the tomato pathogen F. oxysporum.
2.2 Biology of Fusarium
In solid media culture, such as potato dextrose agar (PDA), the different special forms
of F. oxysporum
can have varying appearances. In general, the aerial mycelium first appears white,
and then may change to a variety of colors - ranging from violet to dark purple - according to the
strain (or special form) of F. oxysporum.
If sporodochia are abundant, the culture may appear cream
or orange in color (Smith et al., 1988).
F. oxysporum produces three types of asexual spores: microconidia, macroconidia, and
chlarnydospores (Agrios, 1988).Microconidia are one or two celled, and are the type of spore most
abundantly and frequently produced by the fungus under all conditions. It is also the type of spore

most frequently produced within the vessels of infected plants. Macroconidia
gradually pointed and curved toward the ends. These spores are commonly
are three to five celled,
found on the surface of
plants killed by this pathogen a

Due to the growth of the fungus within the plant's vascular tissue, the plant's water supply is greatly
affected. This lack of water induces the leaves' stomata to close, the leaves wilt, and the plant
eventually dies. It is at this point that the fungus invades the plant's parenchymatous
tissue, until it
finally reaches the surface of the dead tissue, where it sporulates abundantly (Agrios, 1988). The
resulting spores can then be used as new inoculums for further spread of the fungus
Due to prolonged survival in soil as a saprophyte and as resistant structures, F
oxysporum is difficult to control (Mujeebur and Shahana, 2002; Borrero et al., 2004). Among control
strategies available for Fusarium wilt management, soil fumigation and use of resistant cultivars are
the most used. Biological control of plant pathogens using antagonistic
fungal and bacterial strains is
gaining increasing importance. Soil has untapped potential and contains several potential biocontrol
agents (BCAs) such as Pseudomonas spp., Trichoderma spp. and non-pathogenic Fusarium spp. that
have shown high antagonistic activity against several soil-borne pathogens (Fuchs et al., 1999;
Ramamoorthy et aI., 2001). So far, several bacterial and fungal antagonistic strains have been shown
to reduce the damage caused by different pathogens, including F oxysporum f. sp. Iycopersici
(Postma and Rattink, 1992; Alabouvette, 200 I; Moretti et al., 2008).
The best recommended
way to control the disease is selecting resistant varieties of tomato (Silva and
Bettiol, 2005). Recently there have been many reports about using bioactive compounds from
biological control agents which were extracted from different fungi that inhibit many plant
pathogenic fungi, including Fusarium wilt of tomato (Soytong, 1992). These bioactive compounds
are Tricotoxin A50 extracted from Trichoderma harzianum PCO1; and Chaetoglobosin C extracted

from Chaetomium globusum that have been reported to elicit resistance or immunity in plants by
inducing oxidative burst in plant cells (Nuchdonrong, et al., 2004; Soytong, 2002).
So far, several bacterial and fungal antagonistic strains have been shown to reduce the damage
caused by different pathogens, including F. oxy:sporum f. sp. Iycopersici (Postma and Rattink, 1992;
Alabouvette, 2001; Moretti et al., 2008). Some studies have shown that the combined effect of
antagonism and plant growth promotion by BeAs suppresses Fusarium wilt disease in several crops
(De Boer et aI., 2003; Fahri and Murat, 2007).

The following ten accessions of tomato were used for the study:
.

Dextrose Agar (PDA) and incubated at room temperature with the morphological
characteristic of Fusarium been studied under compound microscope. F. oxysporum after
incubation was purified by repeating sub-culture into fresh sterile media until pure culture
were examined on the microscope. Propa!?ules was prepared in 100ml distilled water. The
resultant suspension, with a concentration of 10 6 _10 7 propagules per ml was used to inoculate
tomato plants 2wks after transplanting.
3.5 Screenhouse experiment:
The experiment was in completely randomized design with 3 replicates
comprising of 90 space pots of accession's population maintaining intra and Inter spacing of
0.5m and 1m within the pots. Platform comprising of bamboo were made,occupied by 10m
by 5m land area space in which the pots was placed to avoid soil borne pathogen into the pot
experimental
pots.
Cultural practices: wetting and weeding were regularly observed.
Trans plan ting:
Tomato seedlings of 4 wks old were transplanted into pots containing sterilized
Tomato accessions = 10
Fusarium strains = 2 most virulent + 1 control = 3

All data were subjected to analysis of variance (ANOYA) and mean were separated DMRT
(Duncan Multiple Range Test)

% range scale Value
1-20.0 1 Resistant (R)
20.01-40.00 2 Mean resistant (MR)
40.01-60.00 3 Mean susceptible (MS)
60.01-80.00 4 Susceptible (S)
~0.01-100.00 5 Highly susceptible (HS)
Kavak and Boydak, 2006

The'result of the effect of Fusarium wilt on agronomic and yield parameters of the
tomato accessions are presented in Table 2, 3, and 4. The number of branches, plant height and
number of leaves per plant recorded in this study were as a result of their genetic resistance. The
resistant accessions maintained their leaf numb~rs despite the Fusarium,wilt.
Based on the number of leaves and plant height on Table (3), NG/MRIMA Y/09/005
has 53.68cm for Strain 1 and 51.78cm for strain 2 while NG/MRIMAY/09l006
has 54.88cm for
strain 1 and 65.89cm for strain 2 and are more resistant to both strains of Fusarium inoculated and
the accession that recorded the highest number of the leaves/plant is NG/MRIMA Y/09/006.
Yield parameters such as number of fruits harvested were considered important
indicators for the Fusarium wilt Table (4), in this study, the tomato fruits were harvested when they
were firm and their colour fully developed. The number of fruit Iplant of the control is higher than
the infected except in some cases which could be as a result of environmental factors, thus the
Fusarium affects the number of fruitiplaI1t.NGIMRlMAY/09/006
produces the highest number of
fruit under infection, with strain 1 with having 4 and strain 2 with 2.67
The incidence was compared among the varieties during the study on Table (2), both
partially and incompletely wilted plant were encountered on the field, the result shows that the
incidence of fusarium wilt on tomato is high in NGIMRIMA Y/09J005, having 3.50 to strain 1 and
3.00 to strain 2 while NGIMRIMA Y/09/006 shows minimum resistance to the infection, having 2.33

to strain 1. A common feature on the fusarium wilt -on plant were collected from thO
presence of varying degree of chlorosis.

ROMAROUND 2.67 ab 2.00 a 3.33 ab 45.03 ab 30.85 a 51.26 ab 48.33 a 45.00 a 46.00 a
BESKE 2.67 ab 3.00 a 3.33 ab 45.00 a 44.83 a 52.13 ab 47.67 a 46.67 a 43.00"
NG/M R/MAY/09/005 3.50 b 3.00" 2.67"b 57.10 b 46.00" 44.10 a 40.50" 47.33 a 52.00"
NG/MR/MAY/09/006 2.33 ab 3.00" 4.00 b 36.76" 41.30 b 63.03 b 53.33 a 52.33 a 42.33 a
NG/OE/MAR/09/019 2.67"b 3.00 a 3.33 ab 41.1 a 53.30 ab 49.53" 46.67" 44.67" 46.33 a
PUREWATER 3.00"b 2.00 a 3.67 ab 53.65 a 33.75 b 64.06" 44.50" 56.00" 38.00 a
SANTANA 2.00 a 1.50" 2.33 a 31.67" 26.00" 41.70"b 57.00" 60.50 a 53.67"
NG/AO/MAY/09/011 2.00" 3.00 a 2.33 a 33.13 a 53.33"b 37.03" 56.00 a 44.33" 52.33 a
NG/AA/MAY/09/030 3.50 b 2.33 a 3.00"b 53.35 ab 38.13" 48.60 ab 43.00 a 50.67" 46.33 a
NG/TB/ AUG/09/006 2.00 a 3.00 ab 3.00 ab 48.80 a 48.80 a 49.83" 54.33" 45.67" 43.67"
Means follow by a common letter in each column are not significantly difference by DMRT at P =
0.05

TABLE 3: Growth performance of tomato accessions
Accessions Plant height Number of Leaves number of branches
51 52 CONTROL 51 52 CONTROL 51 52 CONTROL
ROMAROUND 47.39" 31.96"b SS.40 b 8.22" 8.66 b 8.77" O.SO"b 0.15" 0.25"
BESKE 35.55" 45.23" 60.S0~ 6.33" 7.89 b 8.44" 0.67" 0.25" 0.67"
NG/MR/MAY/09/005 53.68" 51.78 bc S4.70 b 7.94 b 7.00 b 9.11" 0.33" 0.33" 1.00 b
NG/MR/MAY/09/006 54.88" 65.89" Sl.30"b 7.56" 10.89" 8.67 b 0.33" 1.67"b 0.7S"b
NG/OE/MAR/09/019 37.48" SS.OSb Sl.78"~ 6.00" 11.00" 7.SS b 1.00" 0.67"b 0.67"
PUREWATER 38.76" 35.13"b 46.38"b 7.00 b 6.5S"b 7.5S b 0.33" 0.50" 1.00"b
SANTANA 37.73" 25.23" 36.76" 7.44 b 5.67" 8.22" 0.25" 0.45" 1.00"b
NG/AO/MAY/09/011 47.21" 44.07"b 38.93" 7.4S" 6.67"b 5.77" 0.33" 0.39" 0.33"
NG/AA/MAY/09/030 41.15" 44.53"b 51.32"b 6.78 b 6.67"b 8.00" 0.45" 0.36" 0.33"
NG/TB/ AUG/09/006 40.72" 44.76"b 44.6S"b 6.33 b 6.77 b 7.44" 0.35" 0.19" 0.33"
Means follow by a common letter in each column are not significantly difference by DMRT at P =
0.05

Table 4: Yield parameter of tomato accessions
ACCESSIONS .
Number of fruits
$1 52 CONTROL
ROMAROUND 2.67 3 0.50 3 2.67 3
BESKE 1.00 3 2.00 3 3.33 3
NG/MR/MAY/09/00S 1.33 3 2.00 3 3.33 3
NG/MR/MAY /09/006 4.00 3 2.67 3 2.33 3
NG/OE/MAR/09/019 0.67 3 2.00 3 1.67 3
PURE WATER 1.33 3 0.67 3 2.33 3
SANTANA 1.00 3 0.00 3 1.67 3
NG/ AO/MAY /09/011 1.67 3 2.67 3 0.67 3
NG/ AA/MAY /09/030 0.00 3 1.00 3 2.33 3
NG/TB/ AUG/09/006 0.67 3 2.00 3 1.33 3
Means follow by a common letter in each column are not significantly difference by DMRT at P =
0.05

The tomato accessions were found to vary in their resistance to strain 1 and strain 2 of
Fusarium oxysporumf
sp. Lycopersici .This study shows that some diversity exists in the tomato
accessions.
Severity test for strain 1 shows that 7 varieties showed mean resistance while
NGIANMAY/09/030, Pure wate~ and NG/MRIMAY/09/005 were susceptible. Maximum rating was
3.5 on NG/MRIMAY/09/005 and NGIANMAY/09/030 when challenged with stain 1 on the field.
Under field condition, many of the varieties that were grown were severely affected. Almost all
varieties were susceptible to strain 2 of the inoculated Fusarium
It is well documented
that the occurrence of disease in plant was found to depend on at
least two components: pathogen and its host plant; and for disease development requires favorable
environmental
condition. This study showed the different resistant level of the ten accessions to
Fusarium wilt disease which is a soil borne disease.
NG/MRIMA Y/09/006 exhibited minimum resistance in terms of disease severity,
number of leaves and fruit yield, with its yield comparably
high, which makes the variety as the
best performing accessions used. It was observed from the data taken that all the tomato
accessions inoculated with the fungi, fusarium oxysporum fsp .lycopersici shows the symptoms
of Fusarium wilt, therefore the best way to control the disease is by planting under irrigation
during the dry season

Based on this study, NG/MR/MA Y/09/006 is recommended in Fusarium wilt endemic
field and also recommended is NG/AO/MAY/09/011 which is recommended based on high yield
and the level of resistant to Fusarium wilt exercised by these varieties.

·
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