GENETIC AND MORPHOLOGICAL DIVERSITY IN Monodora myristica(GAERTN.) DUNAL IN EASTERN NIGERIA
TABLE OF CONTENT
TITLE PAGE - - - - - - - - i
CERTIFICATION - - - - - - - - ii
DEDICATION - - - - - - - - iii
ACKNOWLEDGEMENT - - - - - - - iv
TABLE OF CONTENT - - - - - - - v
LIST OF TABLES - - - - - - - - viii
LIST OF FIGURES - - - - - - - - ix
ABSTRACT - - - - - - - - - x
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND INFORMATION
1.2 GENETIC DIVERSITY IN PLANTS
1.3RATIONALE
1.4 OBJECTIVES
CHAPTER 2
2.1 TAXONOMYAND NOMENCLATUREof Monodoramyristica
LITERATURE REVIEW
2.2 GENERAL DESCRIPTION OF Monodoramyristica
2.3 DISTRIBUTION OF Monodora myristica
2.4 CHEMICAL COMPOSITION OF Monodoramyristica
2.5 USES OF Monodoramyristica
2.6 GENETIC DIVERSITY IN ANNONACEAE
2.7 TECHNIQUES IN MOLECULAR ANALYSIS OF GENETIC DIVERSITY
2.7.1 MOLECULAR MARKERS
2.7.2 PRINCIPLE OF THE RAPD TECHNIQUE
2.8 PLANT LEAF PRESERVATION
2.8.SILICA GEL PRESERVATION
2.9 DNA EXTRACTION
2.9.1 DNA extraction methods
2.10DNA QUANTITATION/QUALITATION
2.10.1 SPECTROPHOTOMETRIC quantification
2.10.2 Quantificatin using flourescent dyes
2.11GEL ELECTROPHORESIS
CHAPTER 3
METHODOLOGY
3.1 GERMPLASM IDENTIFICATION ANDSTUDY SITES
3.2 MORPHOLOGICAL AND YIELD STUDIES
3.2.1COLLECTION OF MORPHOLOGICAL AND YIELD DATA
3.2.2ANALYSIS OF MORPHOLOGICAL AND YIELD DATA
3.3. MOLECULARSTUDIES
3.3.2 PRESERVATION OF SAMPLES
3.3.3LYOPHILIZATION
3.3.4 DNA EXTRACTION
3.3.5SPECTROPHOTOMETRIC ANALYSIS
3.3.6 PROCEDURE FOR GEL ELECTROPHORESIS
3.3.7 RAPD-PCR
3.3.7 AGAROSE GEL ELECTROPHORESIS
3.3.9ANALYSIS OF MOLECULAR DATA
CHAPTER 4
RESULTS
4.1.1 MEANS, STANDARD ERRORS AND ANALYSIS OF VARIANCE
4.1 MORPHOLOGICAL AND YIELD ATTRIBUTES
4.1.2PRINCIPAL COMPONENT ANALYSIS
4.1.3 CLUSTER ANALYSIS BASED ON MORPHOLOGICAL ATTRIBUTES
4.2 GENETIC DIVERSITY
CHAPTER 5
5.0 Discussion
SUMMARY AND CONCLUSION
Appendix
REFERENCES
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND INFORMATION
Monodoramyristica (Gaertn.)Dunal.,also known as African nutmeg or calabash nutmeg, is a tropical tree of the family Annonaceae (Custard-apple family). Its seeds are widely used as an inexpensive nutmeg substitute becauseof the similarity between the two in odour and taste. Nowadays, however, it is less common outside its region of production(Celtnet recipes, 2011)
The genus Monodora contains approximately 15 to 20 species includingMonodora borealis, Monodoraclaessensii andMonodoragrandiflora.Monodoramyristica is easily recognizable by its very long and pendulous pedicels, an undulate upper bract, a large globose fruit with a black and smooth but finely ribbed surface (Burkill, 1985).
The Calabash nutmeg tree is native to tropical West Africa, where it grows naturally in evergreen forests from Liberia to Nigeria and Cameroon. It is also native to Angola,Uganda and West Kenya (Weiss, 2002). Due to the slave trade in the 18th century, the tree was introduced to the Caribbean islands where it was established and became known as Jamaican nutmeg (Barwick 2004). In 1897, it was introduced to Bogor Botanical Garden, Indonesia, where the trees flowered on a regular basis but no fruit could yet be collected (Weiss, 2002).
1.2 GENETIC DIVERSITY IN PLANTS
Genetic diversity refers to any variation in the nucleotides, genes, chromosomes, or whole genomes of organisms. At its most elementary level, it is represented by differences in the sequences of nucleotides (adenine, cytosine, guanine, and thymine) that form the DNA within the cells of the organism. Nucleotide variation is measured for discrete sections of the chromosomes, called genes. Thus, each gene comprises a hereditary section of DNA that occupies a specific place of the chromosome, and controls a particular characteristic of an organism (Harrison et al, 2004).
Diversity enhances the chances of populations’ adaptation to changing environments. With more variation, it is more likely that some individuals in a population will possess variations of alleles that are suited for the environment. Such individuals are more likely to survive to produce offspring bearing that allele. The population can thus continue for more generations because of the success of these individuals (NBII, 2011).
Most organisms are diploid, having two sets of chromosomes, and therefore two copies (called alleles) of each gene. However, some organisms can be haploid, triploid, tetraploid or more (having one, three, four or more sets of chromosomes respectively) (Harrison, et al, 2004). Within any single organism, there may be variation between the two (or more) alleles for each gene. This variation or polymorphism is introduced either through mutation of one of the alleles, or as a result of reproduction processes,especially if there has been migration or hybridization of organisms, so that the parents may come from different populations and gene pools. Harmless mutations and sexual recombination may allow the evolution of new characteristics which increases diversity(Andayani,et al.,2001).
Each allele codes for the production of amino acids that string together to form proteins. Thus differences in the nucleotide sequences of alleles result in the production of slightly different strings of amino acids or variant forms of the proteins.These proteins code for the development of the anatomical and physiological characteristics of the organism, which are also responsible for determining aspects of the behavior of the organism (Harrison, et al, 2004).
Plant diversity is part of the biological diversity and contributes towards achieving food security, poverty alleviation, environmental protection and sustainable development(Frankel 1984). It is being eroded rapidly in important spice plants and other crops mainly because of replacement of traditional landraces by modern, high yielding cultivars, natural catastrophes (droughts, floods, fire hazards, etc.), as well as large scale destruction and modification of natural habitats harboring wild species(Frankel 1984, Bramel-cox and Chritnick, 1998).M. myristica population is threatened by urbanization which damages its natural habitat, and leads to the cutting of most of the trees without replanting. Additionally, the plant is listed under Kew’s difficult seeds due to its inability to easily grow outside its natural habitat(Burkill, 1985). Genetic variation in traditional landraces and wild species is essential to combat pests and diseases and to produce cultivars better adapted to constantly changing environments(FAO, 1994).
Molecular tools such as have been found to be more useful and accurate in the study of inter-species and intra-species genetic diversity in several plants. Randomly amplified polymorphic DNA (RAPD) markers have been successfully employed for determination of intraspecies genetic diversity in several plants. These include Phaseolus vulgaris (Razviet al., 2013),Ocimumspp (Sairkaret al., 2012), Chrysanthemum (Martin et al., 2002), Annonacrassiflora( Cotaet al.,2011), Prosopis ( Goswami and Ranade, 1999), date palm (Corniquel and Mercier, 1994), papaya (Stiles et al., 1993), poplars (Bradshaw, et al., 1994) and amaranths (Ranade, et al. 1997). No such attempt has so far been reported for Monodoramyristica
1.3RATIONALE
M. myristica is largely harvested from the wild and greatly affected by wild fires, urbanization, reckless and uncontrolled felling of trees for timber and firewood without replanting. There is need, therefore, to initiate breeding programs for this orphan crop by first documenting available genetic and phenotypic variations in this crop. The present report was done with this in mind, and should provide the much needed baseline for further studies.
1.4 OBJECTIVES
The general aim of the project was to characterize accessions of African nutmeg inSouth eastern Nigeria and estimate the range and distribution of genetic diversity.
The major objectives of this work were:
⦁ To determine the level of genetic diversity among 21 accessions of Monodoramyristica using RAPD technique
⦁ To compare morphological and yield related traits among the accessions using analysis of variance tests
⦁ To confirm the efficiency of RAPD technique in genetic diversity studies of this important plant.
⦁ To identify traits contributing significantly to variation in this species.
CHAPTER 2
LITERATURE REVIEW
2.1 TAXONOMYAND NOMENCLATUREof Monodoramyristica
Monodoramyristicahas been classified as shown in Fig 1.
Fig 1.Classification of M. myristica
Kingdom Plantae – plants
Division Tracheophyta – vascular plants, tracheophytes
Infradivision Angiospermae – flowering plants, angiosperms,
Class Magnoliopsida
Superorder Magnolianae
Order Magnoliales
Family Annonaceae – custard apples
Genus Monodora Dunal.
Species Monodoramyristica (Gaertn.) Dunal
Source: GRIN (1985)
Monodoramyristica was first described by Joseph Gaertner. It was Michel Félix Dunal, however, who reclassified it into todays’ valid botanical systematics in 1817(Hooker 1831,Brummitand Powell 1996 ).
In Nigeria it is known in different tribesby various namessuch as:
⦁ EDO-èbènọ́yọ̀ọ́bá
⦁ HAUSA-gujiyadanmiya
⦁ IGBO-éhùrù
⦁ IJAW (Nembe)-òkògòló
⦁ YORUBA-ariwo, lakoshe
2.2 GENERAL DESCRIPTION OF Monodoramyristica
TheMonodoramyristica tree can reach a height of 35 m and 2 m in diameter at breast height (DBH). It has a clear trunk and branches horizontally. The leaves are drooping and alternately arranged with the leaf blade being elliptical, oblong or broadest towards the apex and tapering to the stalk. They are petiolate and can reach a size of up to 45 x 20 cm (Weiss, 2002).The flower appears at the base of new shoots and is singular, pendant, large and fragrant. The pedicel bears a leaf-like bract and can reach 20 cm in length. Sepals are red-spotted, crisped and 2.5 cm long. The corolla is formed of six petals of which the three outer reach a length of 10 cm and show curled margins with red, green and yellow spots. The three inner petals are almost triangular and form a white-yellowish cone which on the outside is red-spotted and on the inside is green. The stigmas become receptive before its stamens mature and shed their pollen (protogynous). The flower is pollinated by insects (Courvier, et al, 2006).
The fruit is a berry of 20 cm diameter smooth, green and spherical becoming woody with age. It is attached to a stalk which is up to 60 cm long. Inside the fruit, the numerous oblongoid, pale brown, 1.5 cm long seeds are surrounded by a whitish fragrant pulp. The seeds contain 5-9% of a colourless essential oil (Courvier, et al., 2006).
The fruits are collected from wild trees and the seeds are dried and sold whole or ground to be used in stews, soups, cakes and desserts (Celtnet, 2011). Propagation of Monodora myristica is by seeds, suckers or layers.
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