Introduction to Forest Genetics. Branches, Scope and Problems
Table of Contents
INTRODUCTION:
- Genetics is a branch of biology which is concerned with the study of inherited variations. It deals with the origin of genetic variations and expression of traits resulting from these variations. It is concerned with the transmission, expression, and evolution of genes. Commonly genetics is called the science of heredity.
- The word Genetics has been taking from a Greek word which means “to generate”. This word was first of all used by an English scientist William Bateson in 1905.
- Gene: The molecules that control the function, development and ultimate appearance of an individual.
- Heredity: The resemblance of offspring to their parents is called as heredity.
- The variation due to genes is called hereditary variations.
Forest Genetics
- The hereditary variation in Forest trees is called Forest Genetics.
BRANCHES OF GENETICS:
Following are the branches of genetics:
Classical genetics
which remains the foundation for all other areas in genetics, is concerned primarily with the method by which genetic traits—classified as dominant (always expressed), recessive (subordinate to a dominant trait), intermediate (partially expressed), or polygenic (due to multiple genes)—are transmitted in plants and animals.
Cytogenetics
the microscopic study of chromosomes blends the skills of cytologists, who study the structure and activities of cells, with those of geneticists, who study genes.
Plant cytogenetics
early became an important subdivision of cytogenetics because, as a general rule, plant chromosomes are larger than those of animals.
Animal cytogenetics
became important after the development of the so-called squash technique, in which entire cells are pressed flat on a piece of glass and observed through a microscope; the human chromosomes were numbered using this technique.
Microbial Genetics
After it was discovered that microorganisms have many different physical and physiological characteristics that are amenable to study, they became objects of great interest to geneticists because of their small size and the fact that they reproduce much more rapidly than larger organisms.
Bacterial genetics
is the center of cloning technology. Bacteria became important model organisms in genetic analysis, and many discoveries of general interest in genetics arose from their study.
Viral genetics
is another key part of microbial genetics. The genetics of viruses that attack bacteria were the first to be elucidated. Since then, studies and findings of viral genetics have been applied to viruses pathogenic on plants and animals, including humans. Viruses are also used as vectors (agents that carry and introduce modified genetic material into an organism) in DNA technology.
Molecular genetics
is the study of the molecular structure of DNA, its cellular activities (including its replication), and its influence in determining the overall makeup of an organism.
Genomics
is the study of the structure, function, and evolutionary comparison of whole genomes.
SCOPE OF GENETICS
The scope of genetics is enormous with other topics. Studies have involved viruses, bacteria, and a wide variety of plants, and animals and in levels of biological organization from molecule level up to the population. However, the science of genetics has been used in the areas of agriculture and medicine mainly.
Agriculture and Genetics
- In the agricultural plants following four major categories of improvements have been possible.
- more efficient energy utilization during photosynthesis, which results in more food production and growth is increased.
- increased resistance to natural predators and pests, including insects and disease-causing microorganisms.
- production of hybrids exhibiting a combination of superior traits derived from two different strains.
- selection of genetic variants with increased protein value which must be present in the human diet.
The improvements have resulted in the great increase in yield and nutrients value in crops such as; barely, beans, oats, rye, wheat e.t.c.
Animals and Genetics
- Applied research in genetics has developed superior breeds of animals. Enormous increases in usable meat supplies produced per unit of food intake have occurred. For example; selective breeding has produced chickens which grow faster, produce more high-quality meat per chicken and lay a greater number of larger eggs.
- In larger animals such as cows, the use of artificial insemination has been particularly important. The sperm of single male with superior genetic traits may now be used to fertilize thousands of females located in all parts of the world.
Medicines and Genetics
- Advances in genetics resulted in the development of medicines. Numerous disorders in humans have been discovered to result from either a single mutation or a specific chromosomal abnormality. For example, the genetic basis of sickle cell anemia, erythroblastosis fetalis, hemophilia, Down syndrome and countless metabolic disorders in humans has been discovered. Recognition of genetic basis of these disorders has provided direction for the development of treatment and preventive measures.
Recombinant DNA Technology
- Recombinant DNA technology is also an important part of applied genetics. By cloning human genes for such medically important molecules such as insulin and interferon bacteria can serve a source of mass production of the gene products. The recombinant DNA techniques will also play an increasing role in human genetic engineering, which involves the direct manipulation of the genetic material.
- The recombinant DNA techniques have also been applied and used for the improvement of plants. Genes for herbicide and insecticide have been introduced into the plants. Efforts are being made to introduce genes into the cultivated grasses that enable these to form root nodules. This would make plants free from nitrogen fertilizers.
- The study of genes in populations of animals, plants, and microbes provides information on past migrations, evolutionary relationships and extents of mixing among different varieties and species, and methods of adaptation to the environment.
- Another aspect of genetics is the study of the influence of heredity on behavior. Many aspects of animal behavior are genetically determined and can, therefore, be treated as similar to other biological properties. This is the subject material of behavior genetics, whose goal is to determine which genes control various aspects of behavior in animals.
PROBLEMS OF FOREST GENETICS:
Use of Indirect Evidence:
- Direct evidence cannot be obtained It depends upon indirect evidence which requires much time.
- We take dia, seed production or another growth factor, we can determine the quality of a tree with another tree (but, this can be possible due to mgt, soil factor, genetic, environmental factors, etc.)
- If we are using indirect evidence, we would need clear and intelligent men to draw a conclusion.
Time:
- For agricultural crops, the time can be 6 months, 3 months, etc and conclusions can be concluded in a short span of time.
- Due to high rotation, much time is required for progeny and clonal trials. Even trees start seed about 5 – 10 years ago, but it requires trial till rotation age.
Institutional Sustainability:
- Due to institutional instability, experiments which longer spans of time to complete cannot be concluded and hence conclusions cannot be drawn.
- A new person comes and starts another experiment leaving behind the previous one.
- Policy makers are not-technical people that are why the research procedure is suffering.
Uncertainty and need for continuous experimentation:
- Therein uncertainty and needs for the continuous experiment. Eg poplar is giving better results at one place; it is not necessary that the same results are obtained from other places.
- The seeds collected may be defected which will affect the whole process.
- Need for continuous experimentation which will take time.
The necessity of Seed Production:
- Seed production is rapid in agricultural crops, but not is the case with forest trees; moreover, seed production is period which creates hurdles in genetics studies.
- Majority of the trees are cross-pollinated, which will affect the quality of the tree seed, this is disturbing research processes.
The scarcity of basic genetic information:
- Lacking genetic data regarding our own ecology.
- If we have some data but it is insufficient.
- For example, if I ask shisham (the most studied tree in PFI) is self-pollinated or cross-pollinated, then what is the answer??? Write your answers in the comments below.
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