Agriculture Reference
In-Depth Information
closely linked to a marker allele that is easier to recognize. MAS tools will continue
to be needed in the future to develop superior varieties.
g
e n of m i C is
Watson and Crick received the Nobel Prize in physiology and medicine in 1962 for
their discovery of the molecular structure of nucleic acids and their significance in
transferring information in living organisms. Every living organism contains chro-
mosomes that consist of strands of DNA. It is through the nucleotide subunits of the
DNA that genetic information is translated into proteins and the building blocks of
living organisms to produce new cells and individuals.
Since this discovery, great strides have been made to understand the genetic code
and how it functions in determining new cells and individuals.
Genomics
is the study
of an organism's entire genome or hereditary information encoded by its chromo-
somes. It results in the complete sequencing of one set of chromosomes of an organ-
ism. DNA was first sequenced in 1977, and the sequencing of genetic material took
root in the 1980s and has gathered pace since then; today, many biological species,
including viruses, bacteria, yeasts, insects, worms, fish, and even vertebrates have
complete sequencing of their chromosomes.
The human genome was sequenced and completed in 2003 for all 24 distinct chro-
mosomes. They consisted of about 3 billion base pairs and 20 to 25,000 genes. Various
crops have had their genomes sequenced, including wild mustard (
Arabidopsis thali-
ana
, 2000), rice (
Oryza sativa
, 2002), poplar (
Populus trichocarpa
, 2006), and grapes
(
Vitis vinifera
, 2007). Other crops being sequenced include wheat (
Triticum aestivum
),
maize (
Zea mays
), tomato (
Solanum lycopersicum
), and potato (
Solanum tuberosum
).
Gene mapping
provides a plant breeder with the location of specific genes of
interest in relation to the various chromosomes. This has been accomplished by using
microarray tools and bioinformatics. The microarrays use known specific sequences
of DNA to scan the sequence of a genome to identify genetic variation at specific
locations.
Bioinformatics
or
computational biology
uses mathematics, statistics,
computer science, informatics, chemistry, and other disciplines to solve biological
problems at the molecular level. It uses these tools to make sense of the large amount
of information generated by chromosome sequencing. Bioinformatics also helps in
gene sequencing to search for genes and regulatory sequences within a genome.
Functional genomics
is a field of molecular biology that attempts to make use
of the enormous quantity of data collected from genome projects to describe gene
function and interactions. It focuses on the dynamic aspects of gene transcription as
opposed to the static data available from gene sequencing. It also uses DNA microar-
rays and various electrophoresis and mass spectrometric tools to collect needed data.
It provides the scientist with information concerning the location of specific genes
needed for development of improved new varieties from a much wider spectrum of
organisms than the closely related species that used to be the only source of new
variation. This area of research will continue to be of immense value as humans
better understand the variation, working, and location of genetic material needed to
develop better crops for future food security.
