The Generation of Plant Breeding

INTRODUCTION

When humans became food gatherers, they collecting useful plants surround them. Gradually, more plants were recognized and used as food and other needs. Fresh food became more varied.  Not only fruits, but also seeds, tubers, and leaves. Then they learn and able to process theirs. The generation of plant breeding can not be separated from human history. If you want to read in the PDF version, you can visit researchgate.net

The types of plants used, diverse among places. The plants use as food were dependent on the abundance of plant species in each place. For example, plant types and diversity. The tropical area was different from the plants in the desert or at the poles. The list of plant species used was diverse among civilizations, such as mainland, coastal, and poles.

First Generation Of Plant Breeding

The domestication of Oryza rufipogon was an interesting example.  Oryza rufipogon is the ancestor of modern rice. Based on a scientific report,  in 10,000 BC, humans who lived around the Yang Tse River had used Oryza rufipogon seeds as food. They always collect the seeds and then replant them. By that time, the activities were spread to the southern area, together with the migration process, including Indonesia. For the history of plant utilization in Indonesia, you can click here.

Human civilization then developed.   Some parts of plants were usually eaten, then they replant. Such as seed, stems, fruit, and others.  Nomad habit, causing humans always moving to other places which full of resources.  Most importantly, they start to bring the seed or other plant parts for their reserve.  When needed directly they replant in the new place.

Civilization and farming gradually grew.  Humans began to make a list of cultivated plants.  They did selection to choose the better one. The selection has been done for decades or even centuries. Selection then obtaining local germplasm with high uniformity.

Population explosion

The population grew and humans explore more places for food reasons.   When they knew about navigation,  exploration massively happen.  It also affects the way humans look how to utilize the plants they found. 

Civilization contact, between civilization, also enhance human knowledge about plants and foods.   Domestication, as well as adaptation selection, are characteristic of the first generation of plant breeding.

Second Generation Of Plant Breeding

There were two factors that drive the change of plant species utilization. The industrial revolution and food security.  Prediction about food security and population explosion was mention by Thomas Robert Malthus in his book An Essay on the Principle of Population in 1798. It caused the activities of exploitation of all-natural resources, increase massively.  

Exploration and exploitation of the new world are carried out in almost every corner of the earth. The positive impact of this era was the development of knowledge in agriculture. The mendelian genetic theory has a broad impact on the approach and achievement of plant breeding.  Then green revolution efforts break the Malthusian theory.

From Mendel to Green Revolution

Before Mendelian, plant breeding struggle with phenotype-based selection (physical character) and produce many cultivated plants. Domestication of wild plants into cultivated plants was the characteristic of this phase. The main food crops, such as rice, corn, wheat, and potatoes, are successful examples of human efforts to meet their needs.

Modern plants then created.  They had better vigor and high yields.  More resistant to both stress, environment, and disease.  Also had wider adaptability.  Domestication, generation to generation, change physically in the expected direction. 

Plants selection during this phase was still open-pollinated, which gradually become uniform populations.  Let’s say, the phenotype-based selection is the longest phase in the history of plant breeding.

After the Mendelian era (1865) until the green revolution (the 1950s), the process of plant breeding became more complex.  More efforts to produce more hybrid varieties.  Many germplasm collections from previous work causing the result to also become more complex.

This era successfully restrains once again the Malthusian theory.  Achievements of Norman Borlaug in producing wheat varieties that could create world food security at that time.  Then Borlaug won the Nobel Prize in 1970 and became The Father of the Green Revolution.

The natural damage rate then decreasing because of the intensification of agricultural products. The direction of plant breeding then focuses on optimizing the production potential of hybrid varieties. The utilization of germplasm was then increasingly intensive in order to get new hybrids that have higher yields.

Third Generation Of Plant Breeding

The plant breeding phase then continues with efforts to produce hybrids that are not only high yield but also have more complex traits in disease resistances. Germplasm exploration is even more diverse.  It Includes the use of landraces and wild types from its center of origin.

The new approaches also emerge in agriculture such as biotechnology in a broad definition.  Start from in vitro culture techniques.  By using it,  plant propagation became faster, easier, and shorter in duration.  Some achievements of tissue culture to support plant breeding:

• Higher chance to produce the inter-specific hybrid. 
• In vitro chromosome doubling method becomes easier. 
• Utilization of somaclonal variations from tissue culture processes
• Production of double haploid plants to develop uniform lines
• Utilization of radiation technology

From tissue culture to GMO

After the boom in tissue culture, technology then moves towards. Genetic engineering became a new trend.  The effort to produce new super varieties using genetic engineering, amidst the pros and cons of its effects of genetically modified organism (GMO).

The technology makes it possible to transfer genes between organisms. Pros and cons still continue to this day. Contra discussion, actually more on the impact of GMO on humans and the environment.

When the pros and cons of GMOs still continue, the development then turns to a molecular approach. It started when humans finally can reveal the genome of the organism by sequencing technology.   The success of the molecular approach allows plant breeders to make a selection without waiting till plants producing fruit. Plant breeders also have the possibility to make multiple selections of several characters such as agronomic and disease resistance, at the same time.

In this phase, cell language from DNA (genome), RNA (transcript), amino acids, proteins, and complex metabolites can be understood through the fast development of computer science.

Some commercial vegetable crops developed by the molecular approach have released.  Compared to GMO, Its approach is safer.  The process was only to optimize the selection by using bioinformatics analysis.  All process is natural, but assisted by technology.

From GMO to Molecular Markers

The development of molecular technology then ignites brilliant ideas from scientists about the possibility of editing the composition of the plant genome (genome editing).

Previously, genetic engineering was carried out to insert foreign genes from outside into the plant genome. But, the genome-editing technique is actually only utilizing DNA data that already exists in the cell.  The amounts, types, locations, and action modes from each gene in the plants have mapped. By editing these genes can be turned ON or OFF functionally.

In some cases, DNA analysis brought the fact that useful genes present in modern plants have turn out to be partially inactive due to the long process of breeding. The hope is that by reactivating the genes, plants will get a better phenotype. And vice versa with harmful genes, which at this time can be turned off to increase plant vigor.

Nowadays, the developments in the molecular approach continued.  After Meuwissen in 2001, introducing the idea of ​​the possibility to do selection during the breeding process using genomic data.  The idea was, using an algorithm statistical-based to do the selection.

Integration of Statistics With Molecular Biology

The algorithm was developed by combining the application of genetic, molecular, computer, and statistical science. In-plant breeding, It seems that will become phenomenal achievements.  The process of assembling new varieties by utilizing digital genetic information.  It was used as a model and tool to make a comprehensive selection. 

All plant characters will be revealed since the plant is still in the seedling stage.  Selection will be based on genetic estimated breeding value (GEBV). This technique allows the process cycle of variety development to become very fast with a high level of precision.

Fourth Generation Of Plant Breeding

Plant variety improvement for nutrient quality content is part of the third generation of plant breeding. For example, corn with a high content of lysine has been widely commercialized to meet the needs of the industrial world.

At present many types of wheat were used for the needs of raw materials for specific food products. Other achievements; sunflower plants with high oleic acid content in the seeds, rice seeds with high pro-vitamin A content (very well known as Golden Rice), tomatoes that have a long shelf life, and many other examples.

Some examples of achievements above are the work of scientists dedicated to producing new plant varieties with added value, which not only can produce high and are resistant to disease but also have a positive impact on the fulfillment of human nutrition.

What about the fourth generation of plant breeding generation?. At present thousands of genomic data from cultivated plants, wild types, and varieties are available.  It is increasingly accessible to scientists. The abundance of genomic data makes it easier for scientists to map, study, analyze, and understand in detail. 

Genes function revealing

The functions from genes to proteins levels more easily and precisely. At the same time, scientists have also been able to map the composition of the human genome in a more complete and detailed way.  

As same as plants, the genes in each human chromosome have been mapped and increasingly understood the performance and copy-linkages with other gene functions. From the results of the mapping, it was easier to understand the link between human genes and various diseases, as well as the correlation of human genes with energy intake and environmental factors.

With the cellular specific mechanism, bioactive content, as molecules contained in food will be a signal, resulting in changes in the expression of genes, proteins, and metabolites, which leads to physical expression. Each person is a unique individual and has differences from other humans. For example, nutritionally, it might be easier to understand the consumption of coffee which gives different effects (even with siblings themselves).

From Genomics to Nutrigenomics

The development of these two disciplines can eventually be combined into a scientific discipline based on the understanding that nutrition/food consumed will affect the human genes, directly or indirectly. Human genes associated with triggering the disease/physiological abnormalities, its activity is influenced by the nutrients consumed.

So that diet menus and daily food consumption patterns that are tailored to the specific needs of individuals who have known health risk factors, can be used as prevention efforts to overcome and cure human diseases in the future.

The development of genomic, proteomic, metabolic, and bioinformatic approaches facilitates the meeting of nutrition and genetic science. Food shortages/excess and unbalanced nutrition have an impact that can cause deteriorating health and performance. In its development, this science is referred to as nutrigenomics.

The fourth generation of plant breeding is nutrition-based breeding.  Which is a human effort to keep producing plant varieties with high yields, has a wide range of adaptation both from environmental stresses and diseases, and can meet the specific dietary needs of each individual.

At present some scientists refer to it as a post-genomic era characterized by the integration of the biological, social, and environmental fields in which a new understanding of nutrition is related to physiology, metabolism, and behavior.

As with the history of previous technological developments, nutrigenomics is currently still an interesting discussion related to the uniqueness of each individual’s genome and the presence of an element of epigenetic involvement. The success of the nutrigenomics approach requires integration between disciplines ranging from biology, plant breeding, nutrition, medical, omics, to bioinformatics.

Conclusion From Generation Of Plant Breeding

The history of plant breeding development, in general, is an illustration of human’s efforts to survive. While still meeting the need for food for their species. Several reasons and motives are intertwined in the process.

Predictions of the world’s population, the development of human diseases, climate change that has the potential to affect crop yields, as well as the success that has been achieved in various multi-disciplinary fields, at least becomes a trigger to immediately prove the format of future plant breeding that is precisely capable of meeting the needs of human in the earth.

References:

• Indra. K Vasil.  2008.  A history of plant biotechnology: from the Cell Theory of Schleiden and Schwann to biotech crops.  Plant Cell Reports 27(9):1423-40
• Jean-Michel Salles, Félix Teillard, Muriel Tichit & Maiko Zanella.  2017.  Land sparing versus land sharing: an economist’s perspective.  Regional Environmental Change vol. 17, p1455–1465(2017)
• Meuwissen, Hayes, and Goddard.  2001.  Prediction of Total Genetic Value Using Genome-Wide Dense Marker Maps.  GENETICS April 1, 2001 vol. 157 no. 4 1819-1829
• Maarten Koornneef, Piet Stam.  2001.  Changing Paradigms in Plant Breeding.  Plant Physiol. Vol. 125, 2001
• Neeha and Kinth.  2013.  Nutrigenomics research: a review.  J Food Sci Technol. 2013 Jun; 50(3): 415–428.