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Antimicrobial Properties of Methanol Crude Extract of Kacangma against Crop
Pathogenic Fungi and Preliminary Report of Fungal Disease for Kacangma
YONG LEE KIEN (39425)
Bachelor of Science with Honours
(Plant Resource Science and Management)
2015
Antimicrobial Properties of Methanol Crude Extract of Kacangma against Crop
Pathogenic Fungi and Preliminary Report of Fungal Disease for Kacangma
Yong Lee Kien
39425
This final project report is submitted in fulfilment of the requirement for the
Degree of Bachelor of Science with Honours
(Plant Resource Science and Management)
Plant Resource Science and Management
Department of Plant Science and Environmental Ecology
Faculty of Resource Science and Technology
University Malaysia Sarawak
2015
DECLARATION
I hereby declare that the thesis is based on my original work. All the quotations and citations
have been duly acknowledge. No portion of the work referred to this dissertation has been
previously or concurrently submitted for any other degree programs in UNIMAS or other
institutions of higher learning.
_____________________
Yong Lee Kien
Plant Resource Science and Management
Faculty of Resource Science and Technology
Universiti Malaysia Sarawak (UNIMAS)
APPROVAL SHEET
Name of Candidate: Yong Lee Kien
Title of Dissertation: Antimicrobial Properties of Methanol Crude Extract of Kacangma
against Crop Pathogenic Fungi and Preliminary Report of Fungal
Disease for Kacangma
__________________________
Dr. Freddy Yeo Kuok San
Supervisor
__________________________
Dr. Mohamad Hasnul b. Bolhassan
Co- supervisor
__________________________
Dr Rebicca Edward
Programme Coordinator
Plant Resource Science and Management
Faculty of Resource Science and Technology
Universiti Malaysia Sarawak (UNIMAS)
Acknowledgement
First of all, I must express my greatest gratitude to thank and appreciate my supervisor,
Dr. Freddy Yeo Kuok San, for his unceasing countenance, guidance, patience and motivation
throughout my study. I am deeply grateful to him for providing helpful suggestion and
comments on the draft documents leading to this thesis. His guidance will be remembered
forever by me. Besides that, I extend my gratitude to my co-supervisor, Dr. Mohamad Hasnul
b. Bolhassan, for his practical guidance and support during my entire study period.
I would like to thank the Agriculture Research Centre Semenggok Sarawak for
providing materials and experimental guidance for my study. Moreover, I would like to thank
the Muara Tuang private farmer owner and other enthusiastic person in Batu Kawa residential
area for providing kacangma planting areas to me. Also, my appreciation goes to the
Department of Plant Science and Environmental Ecology for providing necessary equipment
and facilities in my study.
Last but most importantly, I dedicated this thesis to my beloved family. I will not
forget their sincere love, moral support, countless prayers and endless efforts for my entire
journey in university. This piece of work is also dedicated to my course mates, who had
accompanied me for thousands of hours in my life. They had taught me to be strong and keep
my faith, whenever I have met any difficulties.
I
Table of Contents
Title
Page
I
Acknowledgement
II
Table of Contents
V
List of Figures
List of Tables
V
Abstract/ Abstrak
VI
Chapter 1: Research Background
1
1.1 Introduction
1.2 Problem Statements
3
1.3 Objectives
4
Chapter 2: Literature Review
2.1 Description of Kacangma
5
2.2 Phytochemical Extraction
6
2.3 Antimicrobial Plant Constituents
8
2.3.1
2.3.2
Chemical Properties of Leonurus sibiricus
Chemical Properties of Leonurus japonicus
2.4 Crop Pathogenic Fungi
9
10
11
2.4.1
Glomerella cingulate
11
2.4.2
Fusarium oxysporum
11
2.4.3
Fusarium solani
12
2.4.4
Pyricularia oryzae
12
II
2.4.5
Pestalotiopsis sp.
13
2.4.6
Colletotrichum sp.
13
2.5 Disease of Kacangma
14
Chapter 3: Methodology
3.1 Plant Materials
16
3.2 Methanol Extraction
17
3.3 Dilution of Methanol Crude Extracts
18
3.4 Preparation of Crop Pathogenic Fungi
3.4.1
Potato Dextrose Agar
18
3.4.2
Oatmeal Agar
19
3.5 Inhibition Test on Selected Crop Pathogenic Fungi
20
3.6 Characterizing The Leaf Flavonoid Profile of Kacangma
21
3.7 Disease Description and Isolation of Causal Agent
3.7.1
Fungal Isolation
23
3.7.2
Morphological Identification of Isolated Fungi
23
3.7.3
Physiological Test of Temperature on Isolated
Fungi
24
3.8 Pathogenicity Test of Kacangma Leaves
24
Chapter 4: Result
4.1 Crude Extract from Leonurus sibiricus and Leonurus
japonicus Leaves
26
4.2 Antimicrobial Activity of Crude Extract Obtained from
Leonurus sibiricus and Leonurus japonicus
26
III
4.3 Flavonoid Analysis of Kacangma
28
4.4 Preliminary Report of Kacangma Disease (Leonurus
japonicus)
4.4.1
Symptoms of Disease
30
4.4.2
Morphological Characteristics of Fungi Isolated
from The Disease of Leonurus japonicus
31
4.4.3
Temperature Effects on the Growth of Fungi
Isolated from Leonurus japonicus
33
4.4.4
Pathogenicity Test on Leonurus sibiricus and
Leonurus japonicus
34
Chapter 5: Discussion
5.1 Antimicrobial Testing of Crude Extract of Leonurus
sibiricus and Leonurus japonicus
36
5.2 Flavonoid Analysis of Leonurus sibiricus and Leonurus
japonicus
38
5.3 Preliminary Report of Kacangma Disease
40
Chapter 6 Conclusion and Recommendation
6.1 General Conclusion
41
6.2 Recommendation
42
References
43
Appendix
47
IV
List of Figures
Page
1.1
Title
Leonurus sibiricus produce pink flower (a) and L. japonicus produce
white flower (b).
2.1
Basic structure of flavonoid, C6C3C6 skeleton with two benzene rings (A
and B) and one heterocyclic pyrane ring (C) (Cushnie & Lamb, 2005).
7
3.1
Experimental design of inhibition testing on each selected crop
pathogenic fungi.
20
3.2
Experimental design of two dimensional paper chromatography.
22
3.3
Experimental design of pathogenicity test.
25
4.1
Leaf spot disease of the leaf of Leonurus japonicus
30
4.2
The morphology of isolated Fungus A, Fungus B and Fungus C from
diseased leaves of Leonurus japonicus.
32
4.3
Pathogenicity test of Leonurus sibiricus and L. japonicus by Fungus A,
Fungus B and Fungus C.
35
No.
1
List of Tables
Title
Structures of some selected antimicrobial flavonoids (Cushnie & Lamb,
2005).
Symptoms and fruiting bodies structure of some common pathogenic fungi
(Agrios, 2005).
Page
7
4.1
Inhibition test reaction of Leonurus sibiricus against select crop pathogenic
fungi.
27
4.2
Inhibition test reaction of Leonurus japonicus against select crop pathogenic
fungi.
27
4.3
Overall comparison of flavonoid compounds of Leonurus sibiricus and L.
japonicus collected from different locations and their tentative
identification.
29
4.4
Kruskal-wallis tests on growth rate of Fungus A, Fungus B and Fungus C
incubated in different temperature.
33
No.
2.1
2.2
V
15
Antimicrobial Properties of Methanol Crude Extract of Kacangma against Crop
Pathogenic Fungi and Preliminary Report of Disease on Fungi
Yong Lee Kien
Plant Resource Science and Management
Faculty Resource Science and Technology
University of Malaysia Sarawak
ABSTRACT
Kacangma (Leonurus sibiricus and Leonurus japonicus) is a local medicinal plant in Sarawak, Malaysia.
Antimicrobial properties of methanol crude extract of kacangma were examined against six crop pathogenic fungi
namely, Fusarium oxysporum, Fusarium solani, Glomerella cingulata, Pyricularia oryza, Colletotrichum sp. and
Pestalotiopsis sp.. No significant antimicrobial effects were observed among these tested crop pathogenic fungi.
Flavonoid biosynthesis in kacangma plants that planted in three different locations (Batu Kawa residential area,
Muara Tuang private farm and UNIMAS greenhouse) was analysed by Two-dimensional paper chromatography
and compared. The leaf flavonoid profiles showed distinct polymorphism to one another which indicated the
flavonoid biosynthesis in kacangma was environmentally dependent. Meanwhile, preliminary report on fungal
disease of kacangma was studied. Leaf spot disease was infected in L. japonicus plant and the suspected causal
agent was the unknown fungal species (Fungus B) which was positive in the pathogenicity test. In short,
significant antimicrobial effects of kacangma against the crop pathogenic fungi were not showed, the flavonoid
biosynthesis in kacangma was environment dependent and the suspected causal agent of leaf spot disease in L.
japonicus was Fungus B.
Keywords: Leonurus sibiricus, Leonurus japonicus, polymorphism, leaf spot disease
ABSTRAK
Kacangma (Leonurus sibiricus dan Leonurus japonicus) adalah ubat tumbuhan di Sarawak, Malaysia. Ciri-ciri
antimikrob ekstrak metanol kasar kacangma telah diperiksa terhadap enam tanaman kulat pathogen iaitu,
Fusarium oxysporum, Fusarium solani, Glomerella cingulata, Pyricularia oryza, Colletotrichum sp. dan
Pestalotiopsis sp.. Tiada kesan antimikrob yang penting diperhatikan di kalangan tanaman diuji kulat pathogen.
Biosintesis flavonoid dalam tumbuh-tumbuhan kacangma yang ditanam di tiga lokasi yang berbeza (Batu Kawa
kawasan perumahan, Muara Tuang ladang swasta dan UNIMAS rumah hijau) dianalisis dengan kromatografi
kertas dua dimensi dan dibandingkan. Profil flavonoid daun menunjukkan polymorfism berbeza antara satu sama
lain yang menunjukkan biosintesis flavonoid dalam kacangma bergantung pada faktor-faktor alam sekitar.
Sementara itu, laporan mengenai penyakit kacangma telah dikaji. Daun penyakit tempat telah dijangkiti oleh L.
japonicus dan agen penyebab penyakit yang disyaki merupakan spesies kulat yang tidak diketahui (Kulat B) yang
positif dalam ujian patogenisitasnya. Konklusinya, kesan antimikrob dari kacangma pada kulat patogen kurang
berkesan, biosintesis flavonoid dalam kacangma adalah bergantung pada persekitaran dan agen penyebab
penyakit daun L. japonicus disyaki adalah Kulat B.
Kata Kunci: Leonurus sibiricus, Leonurus japonicus, polymorfism, daun penyakit tempat
VI
Chapter 1 Research Background
1.1 Introduction
Kacangma is a well-known local medicinal plant in Sarawak, Malaysia. The family of
kacangma is Lamiaceae which consist of many herbs that contain phytochemical compounds
involved in various biological activities especially antimicrobial activities (Huang, Liao, &
Tang, 2005; Topcu & Goren, 2007). The vernacular name, ‘kacangma’ is widely used in
Malaysia which refer to two different species, namely Leonurus sibiricus and Leonurus
japonicus. These herbaceous plants are native to the tropical Asia, India, China, Africa,
Myammar and America (Mominul Islam & Kato-Noguchi, 2014). It can spread easily through
seeds on a variety of soil types. The flowering of kacangma indicates the mature stage which
normally achieved three months after sowing. L. sibiricus has pink flower whereas L.
japonicus has white flower.
(b)
(a)
Figure 1.1 Leonurus sibiricus produce pink flower (a) and L. japonicus produce white flower (b).
1
Numerous research studies on the chemical properties of kacangma had been carried
on especially in the health science sector. Kacangma has antimicrobial, anti-platelet
aggregation, anticancer and anti-inflammatory properties (Liang et al., 2013a). For the
antimicrobial properties, the aqueous and ethanol extracts of L.sibiricus were able to inhibit
the gram positive bacteria (Staphylococcus aureus), gram negative bacteria (Saccharomyces
cerevisae) and pathogenic fungi (Aspergillus niger) (Chua & Aminah, 2011). These tested
microorganisms are pathogens that cause skin disorder diseases on human.
In reality, fewer researches were performed on the antimicrobial properties of
kacangma against crop pathogenic fungi as compared to the human pathogenic fungi. This
study focuses on testing the antimicrobial properties of kacangma against crop pathogenic
fungi. The phytochemical compounds responsible for the antimicrobial properties of
kacangma against pathogenic crop fungi may be potentially developed into biofungicide.
Biofungicide is a form of biochemical pesticides that can be applied onto a specific disease
whereby results a better disease prevention and management (Francis & Keinath, 2010).
Biofungicide is environmental friendly which protects and maintains the equilibrium of
ecosystem.
One of the groups of phytochemical compounds which involved in antimicrobial
activities is flavonoids. Flavonoids are produced in all vascular plants but their biosynthesis is
influenced by diverse environmental factors (Downey, Dokoozlian & Krstic, 2014). The
different environmental factors are referring to the variations of temperature, moisture, air
movement and soil type. Thus, the leaf flavonoid contents of kacangma collected from three
different locations were tested in this study and compared.
2
Kacangma is traditionally used by the Chinese as herbs that help in heart disorders,
diuretics and dispel edema (Liang et al., 2013b; Mominul Islam & Kato-Noguchi, 2014).
Moreover, it can also use to regulate menstrual disturbances and promote blood circulation
(Liang et al., 2013b). Generally, it will be chopped, dried and cooked with ginger chicken
soup. Nowadays, well packed dried kacangma are available at the local market and usually is
made from L. sibiricus which is believes to be better than L. japonicus because of its pink
flower.
1.2 Problem Statements
Excessive practices of fungicides in plantation had triggered the eco-warning alarm
and thereby the intervention of biofungicide was strongly promoted. The productions of
potential phytochemicals for biofungicide may be are environment dependent including
flavonoids.
Kacangma is a medicinal plant that contains various phytohormones with potential
antimicrobial properties. There are numerous research had carried on the antimicrobial
properties of kacangma but limited on fungal diseases for kacangma.
3
1.3 Objectives
The first aim was to test if the crude extract of kacangma (Leonurus sibiricus and
Leonurus japonicus) will inhibit the growth of selected crop pathogenic fungi. The first
objective was to obtain crude extracts of kacangma through methanol extraction. The second
objective was to observe the inhibition effects of different concentration of kacangma crude
extract against the growth of selected crop pathogenic fungi. The second aim was to test if any
polymorphism of the flavonoid content will formed in kacangma that grew in different
environment. The third objective was to compare and study the flavonoid profile of kacangma
leaves collected from different locations.
The third aim was to conduct preliminary report for fungal disease of kacangma. The
fourth objective was to observe and describe the infection symptoms on diseased leaf of L.
japonicus. The fifth objective was to isolate any associated fungal species from the diseased
leaf of L. japonicus and conduct physiological test of different temperature. The sixth
objective was to conduct pathogenicity test on healthy leaves of kacangma by the isolated
fungal species.
4
Chapter 2 Literature Review
2.1 Description of Kacangma
Kacangma is referred to L. sibiricus and L. japonicus in this study. Both species are
belonging to the family of Lamiaceae. The two species are near identical morphologically
except for their flower color. L. sibiricus has pink flower whereas L. japonicus has white
flower. Both species are annual plants with square stem that is erect, stout and grooved (Datta,
1945). They grow upright to height ranges of 20 cm to 25 cm and the simple leaves are
arranged in opposite dessucate pattern. This plant has polymorphic leaves which refer to ovate
shaped leaves with crenate margin and cross-venulate venation and lobed shaped leaves with
entire margin and palmate venation.
Moreover, both of the plants develop beautiful spike pattern of inflorescence. Each
flower is shaped in galeate with an oblong upper lip and one stigma that could yield four seeds
(Edley, n.d.). L. sibiricus and L. japonicus can multiply through seed and cutting. The dark
brown oval seeds can germinate in moist soils with adequate nutrients and sunlight within a
week. Normally, the plant matures in approximately three months after sowing.
5
2.2 Phytochemical Extraction
Extraction is a process to extract the potential biological components from the desired
plants. Various extractions methods were designed and conducted depending on the type of
plant samples and desired target compounds. Maceration and Soxhlet methods will extract
phenolic compounds under high temperature condition in a long period, thus reduce phenolic
compound contents in the extract (Dai & Mumper, 2010). These conventional extraction
methods are not suitable used to obtain phenolic compounds which are easily hydrolysed and
oxidised.
Solvent extraction is a common extraction method. Polar solvent can be used to obtain
polar components whereas non-polar solvents can be used to obtain non-polar components.
The polar solvents, methanol was effectively used in extracting low molecular weight
polyphenol compounds including the flavonoids with C6C3C6 skeleton (Figure 2.1) (Dai &
Mumper, 2010; Waterman & Mole, 1994). Various different groups of flavonoids are formed
by oxygenation and substitution on the C6C3C6 skeleton (Table 2.1). These compounds have
three important properties namely antiviral, antifungal and antibacterial (Cushnie & Lamb,
2005).
6
Figure 2.1 Basic structure of flavonoid, C6C3C6 skeleton with two benzene rings (A and B) and one
heterocyclic pyrane ring (C) (Cushnie & Lamb, 2005).
Table 2.1 Structures of some selected antimicrobial flavonoids (Cushnie & Lamb, 2005).
Flavonoid
compounds
Apigenin
(Flavones)
6,8Diprenylgenistein
(Isoflavones)
Kaempherol
Licochalcone A
(Chalcones)
Naringenin
(Flavanones)
Functional groups at each carbon position
2
3
4
5
6
7
8
2’
3’
4’
5’
6’
-
-
-
OH
-
OH
-
-
-
OCH’
-
-
-
-
-
OH
R3
OH
R3
-
-
OH
-
-
-
OH
-
OH
-
OH
-
-
-
OH
-
-
-
R11
OH
-
OCH3
-
-
-
-
OH
-
-
-
-
-
OH
-
OH
-
-
-
OH
-
-
7
2.3 Antimicrobial Plant Constituents
Plants had developed biological system over the century to defend and survive from
pathogens attack. This self-protective system in plant was partly depends on the plant
secondary metabolites with antimicrobial properties. The most abundant secondary
metabolites in plant are the polar phenolic compounds with great antioxidant properties (Dai &
Mumper, 2010).
8
2.3.1 Chemical Properties of Leonurus sibiricus
Leonurus sibiricus possess anticancer and antitumor properties (Satoh et al., 2003). Its
aerial parts contain furanoditerpenelactones and four different diterpene-lactones namely,
leonotinin, leonotin, dubiin and nepetaefuran. These compounds showed cytotoxic action on
leukemia cells in tissue culture moderately (Satoh et al., 2003).
L. sibiricus also exhibit allelopathic action against the surrounding plants (Mominul
Islam & Kato-Noguchi, 2014). The allelopathic components in aqueous methanol extracts of L.
sibiricus were able to interfere and even inhibit the germination and development of Italian
ryegrass (Lolium multiflorum Lam.), garden cress (Lepidum sativum L.) and lettuce (Lactuca
sativa L.) (Mominul Islam & Kato-Noguchi, 2014).
The ascorbic acid and phenolic compounds in L. sibiricus give the antioxidants
properties of this plant. In 100 g of the leaf powder, there are 8mg of ascorbic acids. The
polyphenol contents of L. sibiricus ranges from 4-11mg for one gram of leaf sample
depending on the drying temperature of the sample (Chua & Aminah, 2013).
Antimicrobial properties are also found in L. sibiricus where 50 and 100 mg/mL of the
ethanol extracts and 100 mg/mL of the water extracts of L. sibiricus were able to inhibit
Staphylococcus aureus (Chua & Aminah, 2011). Effective inhibition of Aspergillus niger and
Saccharomyces cerevisiae was observed when 25, 50 and 100mg/mL of the water extracts
were applied to the media separately (Chua & Aminah, 2011).
9
2.3.2 Chemical Properties of Leonurus japonicus
Antimicrobial properties of L. japonicus against bacteria and fungi had been
discovered (Liang et al. 2013a; Yang et al., 2008). L. japonicus seeds contain two
antimicrobial proteins namely, bornyl acetate and borneol that brought effective inhibition
effects against bacteria (Alternaria alternata) and fungus (Ralstonia solanacearum) (Liang et
al., 2013; Yang et al., 2008).
The essential oils of L. japonicus also have antimicrobial activity (Liang et al, 2013a).
L. japonicus mainly contain approximately 33% of diterpenes, 19% of phytone, 14% of phytol,
12% of caryophyllene oxide and 10% of β-caryophyleene and 13% of other less significant
constituents (Liang et al, 2013a). The sesquiterpenes (phytol, phytone and caryophyllene) and
diterpenes of L. japonicus had shown distinctive inhibition effects against Gram-positive
bacteria. The sesquiterpene, β-caryophyleene affects the growth of Enterococcus faecium and
E. faecalis (Liang et al, 2013a).
Ethanol extracts of L. japonicus have the constituents that brought antibacterial
activities against both Gram-positive bacteria and Gram-negative bacteria (Liang et al., 2013b).
In the ethanol extract, the arteannuin B compounds able to inhibit Gram-negative bacteria (E.
coli and Enterobacter aerogenes) with Minimal Inhibitory Concentration (MIC) values of
25µg/mL and 50µg/mL. Also in the ethanol extract, the chamigrenal compounds are able to
inhibit Gram-positive bacteria (Macrococcus caseolyticus, Staphylococcus auricularis and
Staphylococcus aureus with MIC values of 25µg/mL to 200µg/mL (Liang et al., 2013b)
10
2.4 Crop Pathogenic Fungi
Crop pathogen is referred to the pathogenic microorganisms that influence and threaten
the growth of vegetation. The resulted fungal diseases had brought numerous losses in crop
production. In this study, six different crop pathogenic fungi were used in the inhibition test
namely, Glomerella cingulata, Fusarium oxysporum, Fusarium solani, Pestalotiopsis sp.,
Colletotrichum sp. and Pyricularia oryzae. All of the stated fungi belong to phylum
Ascomycota.
2.4.1
Glomerella cingulata
Glomerella cingulata is a common crop pathogen in Malaysia that caused anthracnose
disease on oil palms, rubbers and guavas (Snowdon, 2010). The infection symptoms always
start with tiny dark lesion on the leaves and enlarge until the leaves turn black and shed (Wang
et al., 2012). On the fruit, the symptoms are round, necrotic, sunken and red-bordered lesions
on the fruit (Wang et al., 2012).
2.4.2
Fusarium oxysporum
Fusarium oxysporum is a soil-borne pathogen that causes vascular wilt disease on a
broad range of crops in Malaysia such as tomato, guava, banana, melon and whatnot (Dean et
al, 2012). The infection interfere the vascular system of plants, so the plant will suffer from
insufficient water supply. Therefore, the symptoms of vascular wilt disease on the infected
11
plants are stunted growth, wilting and yellowing leaves and brown ring is formed in the
vascular bundle areas (Agrios, 2005).
2.4.3
Fusarium solani
Fusarium solani is hardly differentiated from F. oxysporum by unprofessional
mycologist but a trained mycologist can be identified F. solani by the presence of orange
perithecia in pure culture (Burgess, Knight, Tesoriero & Hien, 2008). It is a soil borne fungus
that cause serious crown, collar and root rots (Burgess, Knight, Tesoriero & Hien, 2008;
Summerell et al., 2011). In Malaysia, this fungus usually infects the tropical fruits like papaya
and banana (Zakariah, Chik, Kong & Salleh, 2012). F. solani is resistant towards most of the
available fungicides (Summerell et al., 2011).
2.4.4 Pyricularia oryzae
Pyricularia oryzae is a fungus that named differently at its different reproductive phase.
At asexual reproduction stage, the fungus is known as Pyricularia oryzae (Agrios, 2005). The
scientific name Magnaporthe oryzae is used at its sexual reproduction stage (Agrios, 2005).
The species name “oryzae” is given based on its major infection on paddy that belongs to the
genus Oryza. The infection will lead to the most destructive rice disease that known as rice
blast which affects the paddy production of Malaysia (Dean et al, 2012). The infection form
12
lesions on the leaves with distinct diamond shaped lesions of white to grey colour and may
enlarge which eventually destroy the entire leaves (Agrios, 2005).
2.4.5 Pestalotiopsis sp.
Pestalotiopsis sp. affects only wounded or stressed plant especially on woody plant and
conifer (Royal Horticulture Society, n.d.). This fungus causes leaf spots, petiole blights and
bud rot of palm in certain cases (Elliott, 2005). In Malaysia, the common infected plants are
rubbers, mangosteens, guavas and lychees (Snowdon, 2010). The infection symptoms are the
steady enlarging tiny brown spots on leaves and the infected fruits turned harder with light
pink colouration (Lim & Sangchote, 2003).
2.4.6
Colletotrichum sp.
Colletotrichum sp. is known as Colletotrichum during anamorph and it is named
differently during teleomorph which is Glomerella (Abd-Elsalam et al., 2010). It is the
common fungi that cause anthracnose disease and rotting of many annual and perennial plants
(Agrios, 2005). Malaysian commercial crops such as cereals, maize, corns, coffee, radish,
papaya and rubber were usually infected by this fungus which brought significant losses in
production (Dean et al., n.d.).
13
2.5 Diseases of Kacangma
Plant diseases are normally caused by infection of pathogenic fungi, virus, bacterial,
nematodes and infestation of insects. For pathogenic fungi, the spores spread and adhere on
the plant parts. The spores are then germinate and develop by utilizing the plant nutrients.
These will threaten the plant health and may cause dieback if infection was severe. The
affected plant parts will show specific symptoms that can be an indication on the causal agent
(Table 2.2). Fungi isolation from the affected plant parts and followed by morphological
identification will allow the identification of the fungi up to the genus level based on their
specific fruiting bodies structures. Then, molecular identification allows the identification up
to the species level. Moreover, pathogenicity tests can be conducted to confirm the isolated
fungus is the disease causal agent of the plant.
Physiological effects on pathogenic fungi growth can be used to classify them into
different groups. For example, every fungus has its own ideal temperature for growth and
sporulation. Based on temperature factor, fungi are divided into three groups namely
psychrophiles fungi that can grow optimally around 10oC, thermophiles fungi that can grow
optimally around 40oC and mesophiles fungi that can grow optimally in between both
psychrophiles and mesophiles preferred temperatures (Madan & Thind, 1998). With the
knowledge on the minimum and maximum temperature limit that pathogenic fungi cannot
thrive, post-harvest management on the kacangma products can be strategized.
14