A growing world population demands innovation in the field of agriculture to meet its nutritional needs. Various techniques have been applied over the centuries, to varying successes.
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Cytogenetics is a branch of genetics that studies how chromosomes relate to cell behavior. It is also a branch of cell biology.1 This scientific field has found application in a number of industries, such as biomedicine, and is increasingly being used in agriculture to address several challenges and enhance agricultural productivity and sustainability.
Cytogenetics: Foundations and Techniques
Malformations associated with the chromosomes in cells lead to genetic diseases, which can be inherited by future generations of an organism. Over the past few decades, fields such as cytogenetics have led to improvements in the diagnosis of several of these diseases.
Intact chromosomes are extracted from live cells, which are then analyzed using various methods. Techniques such as Giemsa banding, centromere banding, quinacrine banding, and fluorescence in situ hybridization (FISH) are used to identify chromosomes.
FISH involves the use of fluorescent probes that can detect specific DNA sequences within a sample. This highly sensitive and rapid technique has been widely applied in preimplantation genetic diagnosis, which is the detection of genetic abnormalities in embryos that lead to disorders such as Huntingdon disease and cystic fibrosis.1
Other techniques utilized include karyotyping, where chromosomes are stained and examined under a microscope to determine size, shape, and number, and comparative genomic hybridization, which compares copy number variations in a genetic sample to a reference sample.
Improving Crop Varieties Through Cytogenetics
The environmental challenges of the 21st century demand more climate change- and pest-resistant crop varieties to feed a growing global population. Breeding crops with these desired traits is a key concern amongst agricultural scientists.
Cytogenetics is playing an increasingly vital role in producing crops which can better tolerate floods, extremes of temperature, drought, disease, and pests. Furthermore, this field of genetics and cell biology can provide agricultural producers with more high-yield crops.
Several key food crops have been the target of cytogenetic research in recent years. Rice varieties have been produced with enhanced yield and agronomic performance, and enhanced biotic and abiotic stress resistance. Wheat has been produced with significantly improved gluten and protein contents and increased tiller numbers.
Varieties of rye, peas, sorghum, bananas, capsicum, and sugarcane have also been produced using cytogenetic techniques with improved agronomic traits and stress resistance.2
Varieties of rice, a key crop on which a considerable proportion of the world population relies, have been produced that are impervious to certain diseases and pests that would otherwise reduce their yield, such as the Asian rice gall midge. Infestation of crops by gall midge larvae has a significant negative impact on global rice yields.2
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Cytogenetics in Crop Breeding Programs
Plant breeding itself predates humanity’s understanding of genetics by an order of multiple millennia. Since the dawn of agriculture, humans have selected desirable traits to improve crop size, yield, nutritional content, taste, and aesthetic appeal.
Considerable progress has been made in recent years by employing cytogenetics and related fields such as cytogenetics and metagenomics in the breeding of new varieties of key cereal crops such as sorghum and wheat, legumes, spices, fruits, vegetables, fiber-yielding plants, and aromatic crops with desirable functional and agronomic traits.
Traits that have been selected for in plant breeding programs include Herbicide resistance; improved amino acid, essential vitamin, flavonoid, and protein content; enhanced medicinal, aromatic, and ornamental values; abiotic/biotic stress resistance; enhanced soil nutrition; lower anti-nutritional factors.
Furthermore, new strains of functional and therapeutic food crops have been made possible using cytogenetic approaches.3 Techniques such as FISH and DNA base-specific chromosome painting, have played a key role in the identification, mapping, and localization of chromosome-specific markers in plants, greatly aiding agricultural scientists in plant breeding projects.3
Furthermore, cytogenetics can be used to produce hybrid strains and introduce novel genetic material from wild variants of common crops such as rice, wheat, and legumes.
Addressing Agricultural Challenges with Cytogenetics
Cytogenetics has the potential to address several challenges currently facing agricultural producers, thereby ensuring food security over the coming years. Climate change, population growth, management of pests and diseases, and preserving genetic diversity and some of the key challenges which this field of genetics and cytology can be beneficial.
Future Directions in Agricultural Cytogenetics
There are a number of exciting trends in cytogenetics which promise to revolutionize multiple fields such as agriculture, medicine, and human biology. Optical Genome Mapping (OGM) is one such development and could radically change workflow in cytogenetic research.
This technique is faster than conventional cytogenetic approaches, as it analyzes extremely long stretches of DNA, meaning that fewer pieces of DNA are needed to map an entire chromosome. Because of this, OGM produces fewer errors, according to researchers. Furthermore, as the DNA within chromosomes is analyzed in its “natural” state, no pre-processing or manipulation of genetic material is needed.4
Other trends include the use of advanced bioinformatics and genomic tools to understand complex genetic traits which could be used to produce new strains of crops resistant to various environmental and biological stresses as well as provide new agricultural variants with functional properties such as enhanced nutritional content.
In conclusion, cytogenetics and related fields are proving revolutionary for the agricultural industry, creating hybrid crops, improving disease, pest, abiotand abiotic/biotic stress resistance, and helping to produce future crop variants thatbetter weather the rigors of a changing climate. In short, the field is crucial for ensuring food security for a growing world population in the 21st century and beyond.
Further Reading and More Information
- Encyclopedia Britannica (website) Cytogenetics (cell biology [online] Available at: https://www.britannica.com/science/cytogenetics (Accessed on 04 April 2024)
- Rout, A, Hussain, S & Nanda, S (2020) Molecular Cytogenetics in Agriculture: A Perspective on Rice Improvements Int J, Bioinformatics and Biological Sci. 8 pp.81-88 [online] researchgate.net. Available at: https://www.researchgate.net/publication/349310931_Molecular_Cytogenetics_in_Agriculture_A_Perspective_on_Rice_Improvements (Accessed on 04 April 2024)
- Taludkar, D & Sinjushin, A (2015) Cytogenomics and Mutagenomics in Plant Functional Biology and Breeding PlantOmics: The Omics of Plant Science [online] link.springer.com. Available at: https://link.springer.com/chapter/10.1007/978-81-322-2172-2_5 (Accessed on 04 April 2024)
- Mantere, T et al. (2021) Optical genome mapping enables constitutional chromosomal aberration detection The American Journal of Human Genetics 108:8 pp. 1409-1422 [online] cell.com. Available at: https://www.cell.com/ajhg/fulltext/S0002-9297(21)00217-2 (Accessed on 04 April 2024)