ABSTRACT
The mitotic chromosomal defferences of three varieties of maize (Zea mays everta, Zea mays saccharata and Zea mays turnicata) from root tips were investigated using squashing method. 0.05g of Colchicine, 3:1 ethanol-glacial acetic acid and 70% of ethanol was used for pretreatment and fixation. 1N HCl were used for hydrolysis and 2g of orcein was use for staining. the diploid number of Zea mays everta, Zea mays saccharata and Zea mays turnicatawas 2n=20 each, well spread with few overlapping chromosomes were obtained. Chromosome I with the highest value was the longest chromosome were as the shortest chromosome and the shortest chromosome is chromosome X. In Zea mays evertachromosome I, II and V was metacentrics while the rest are non-metacentrics. In Zea mays sacharata, chromosome I and II are metacentric while the rest are non-metacentrics. In Zea mays turnicata, chromosome I, II and III are metacentrics while the rest are non-metacentrics.
TABLE OF CONTENT
Cover page i
Title page ii
Declaration iii
Certification iv
Dedication v
Acknowledgement vi
Table of content vii
List of tables ix
Abstract x
CHAPTER ONE
1.0
Introduction 1
1.1 Justification 4
1.2 Objectives 4
CHAPTER TWO
2.0 Literature
review 6
2.1 Botany of
maize 6
2.2 Chromosome
number and behavour 7
2.3 Genetic
modification 8
2.4
Cross
between Zeamays species and
hybridization 9
2.4
Intra
specific crosses 9
2.4.2 Interspecific
crosses. 9
2.4.3 Intergeneric
hybridization 10
2.5 Maize
genetics, corn type races and genetic resources 11
2.6 Biotechnology
intervention 14
2.7 Economic
importance 14
CHAPTER THREE
3.0 Materials and
method 15
3.1 Study area 15
3.2 Source of
plants 15
3.3 Pretreatment
and fixation 15
3.4 Hydrolysis 16
3.5 Ethical issues 16
3.6 Measurement of
the chromosomal lengths 16
CHAPTER FOUR
4.0 Results 17
CHAPTER FIVE
5.0 Discussion and
conclusion 22
5.1 Discussion 22
5.2 Conclusion 25
5.3 Recommendation 26
References
LIST OF TABLES
Table
1: The length of the homologue for Zea
mays everta 18
Table 2: The
length of the homologue for Zea mays
saccharata 19
Table 3: The
length of the homologue forZea mays
tunicate 20
CHAPTER ONE
1.0 INTRODUCTION
Maize
(Zea mays L.) is a plant belonging to
the family of grasses (Poaceae). Itis cultivated globally being one of the most
important cereal crops worldwide. Maize is not only an important human
nutrient, but also a basic element of animal feed and raw material for manufacture
of many industrial products. The products include corn starch, maltodextrins,
corn oil, corn syrup and products of fermentation and distillation industries.
It is also being recently used as biofuel. Maize was domesticated from
teosinte, 6300 years ago in Mexico. After initial domestication, early farmers
continued to select for advantageous morphological and biochemical traits in
this important crop (Buckler and Stevens, 2006).
The
genus Zea consists of four species of
which Zea mays L. is economically
important. The other Zeasp, referred
to as teosintes, are largely wild grasses native to Mexico and Central America
(Doeblay, 1990). The number of chromosomes in Zea mays is 2n = 20. Tribe Maydeae comprises seven genera which are
recognized, namely Old and New World groups. Old World comprises Coix (2n =
10/20), Chionachne (2n = 20), Sclerachne (2n = 20), Trilobachne (2n = 20) and
Polytoca (2n = 20), and New World group has Zea
and Tripsacum (Doeblay, 1990)
Taxonomic classification
of maize (Zea mays L.)
Kingdom Plantae
Division Magnoliophyta
Class Liliopsida
Order Poales
Family Poaceae
Genus Zea
Species Z.
mays L.
Sources: (http://wikipedia.org)
It
is generally agreed that maize phylogeny was largely determined by the American
genera Zea and Tripsacum, however it is accepted that the genus Coix contributed
to the phylogenetic development of the species Zea mays (Raduet al.,
1997).
Maize
(Zea mays L.) chromosomes were first
characterized by McClintock (1929) from studies of the first pollen mitosis. In
Zea, a considerable number of
variations from normal chromosome number have been observed. The fact that those
variations in number occur is of importance to the student of maize genetics in
that they may give rise to abnormal ratios that cannot be explained by normal
segregation. It is therefore of considerable importance to have both
cytogenetics and genetics understanding of the material with which one is
working. Variability of chromosome number is not by any means peculiar to Zea, it has been reported in a number of
species that it seems to be more or less a common occurrence in nearly every
species that have been thoroughly studied. It is the purpose of this
investigation to study the mitotic event in maize plant with a view to
ascertaining the regularity of the process in this plant.
Pachytene chromosomes showed better
morphological details for cytological studies (McClintock, 1933). The
chromosomes of maize were individually identified in meiotic stages by
McClintock, which led to many several findings in cytogenetics. This technique
continues to be a valuable tool for studies of chromosomal structure and
function as well as of mitosis itself and It provides the advantage that within
a few days of germination, the chromosomal constitution of an individual can be
determined and the seedling can be saved, grown and used in genetic analysis.
The pachytene chromosomes were identified on the basis of their number, length,
centromere position, prominent chromomeres and heterochromatic knobs (McClintocket al.,1981). Other heterochromatic
regions found in a number of different chromosome regions have also been
described (Rhoades, 1978). The examination of chromosomes of different species
of maize has revealed that the number, size and position of knobs are variable
and that they are found in the maize chromosomes (McClintocket al., 1981).
The identification of mitotic chromosomes
using conventional staining was described by Chen (1969) and Filion and Walden
(1973), while C-banding procedures have shown the presence of stained distal
bands in mitotic chromosomes (Jewell and Islam-Faridi, 1994). Aguiar-Perecin(1985)
described differential staining of the classes of maize heterochromatin:
heavily stained bands on mitotic chromosomes correspond to knobs, while
staining of centric heterochromatin is hardly observed in well-condensed
metaphases. nucleolus organizer region (NOR)-heterochromatin appears
differentially stained but with a lower degree of staining than knobs. No
differential staining was observed in B-chromosomes, but Ward (1980) observed
staining of the B-centric heterochromatin. Furthermore, the analysis of
C-banded mitotic metaphases of maize races with different knob constitutions
showed that large bands corresponding to large and medium knobs alter the arm
lengths of mitotic chromosomes (Aguiar-Perecin and Vosa, 1985). There is need
for squashing and coverslip removal by using a root tip cell suspension from
which chromosomes are then spread onto slides. The method of spreading is an
amalgam of several solid tissue techniques developed for vertebrate chromosomes
(KLIGERMAN and BLOOM, 1977), and generally produces cell monolayers where the
metaphases are complete, non-overlapping, and easily found. A slight
modification in the general procedure yields chromosomes which can be treated
and/or stained to produce patterns of differential banding.
1.1 JUSTIFICATION OF STUDY
Several research works have been
carried out on maize (Zea mays) but
little or nothing has been documented on chromosomal study of maize (Zea mays L.). This study seeks to look
into the mitotic chromosomal study of maize (Zea mays)
1.2 OBJECTIVES
The objective of this study includes:
Ø Identification
of mitotic chromosome number in three (three) different varieties of Maize (Zea mays L.)
Ø To
measure the lengths of the chromosomes
Ø To
identify their location on the centromere.
Ø To
identify overlapping and non-overlapping chromosomes of maize (Zeamays L).
Buyers has the right to create
dispute within seven (7) days of purchase for 100% refund request when
you experience issue with the file received.
Dispute can only be created when
you receive a corrupt file, a wrong file or irregularities in the table of
contents and content of the file you received.
ProjectShelve.com shall either
provide the appropriate file within 48hrs or
send refund excluding your bank transaction charges. Term and
Conditions are applied.
Buyers are expected to confirm
that the material you are paying for is available on our website
ProjectShelve.com and you have selected the right material, you have also gone
through the preliminary pages and it interests you before payment. DO NOT MAKE
BANK PAYMENT IF YOUR TOPIC IS NOT ON THE WEBSITE.
In case of payment for a
material not available on ProjectShelve.com, the management of
ProjectShelve.com has the right to keep your money until you send a topic that
is available on our website within 48 hours.
You cannot change topic after
receiving material of the topic you ordered and paid for.
Login To Comment