Science & Technology (Commonwealth Union) – Jumping genes, also known as transposable elements or transposons, are sequences of DNA that can move around to different positions within a genome. This groundbreaking discovery has revolutionized the field of genetic science, as it sheds light on the mechanisms of genetic variation and evolution. In this article, we will delve into the history, mechanisms, and implications of jumping genes. The History of Jumping Genes The concept of jumping genes was first proposed in the 1940s by Barbara McClintock, a pioneering American geneticist. McClintock observed that certain genetic elements could change their position within the corn genome, which she termed “jumping genes.”
The genetic disparities between pointed cabbage and cauliflower surpass those between humans and chimpanzees, despite both being classified as the same species. Researchers from Wageningen and China embarked on a project to meticulously map the extensive genetic variations within cabbage (Brassica oleracea). Their aim was to facilitate more targeted breeding efforts, such as enhancing nutritional content or bolstering resilience against diseases. The findings of this research were extensively covered in the scientific journal Nature Genetics.
Brassica crops constitute a significant portion of our dietary options, boasting considerable diversity. Yet, intriguingly, cauliflower, broccoli, brussels sprouts, red cabbage, white cabbage, pointed cabbage, and kohlrabi all stem from the same species, Brassica oleracea. The breadth of diversity within this single species raises questions: How can such variation exist, extending beyond mere appearances? Not only do physical characteristics differ, but also the content, encompassing vitamins, antioxidants, and tolerance to environmental stresses like drought, cold, and disease.
While the genome, the collective genetic blueprint, of Brassica oleracea was fairly well-documented, the connection between this genomic diversity and the plethora of vegetable variations remained unclear. To address this gap, researchers from Wageningen University & Research and the Chinese Academy of Agricultural Sciences in Beijing embarked on an international collaboration. Together, they sequenced the DNA of 23 different cabbage cultivars and meticulously analyzed this data alongside existing genome information.
Guusje Bonnema, a plant breeding researcher at Wageningen University & Research, explains the creation of a pan-genome, which provides an overview of the diverse genes found in various cole crops. Bonnema and fellow researcher Chengcheng Cai, from the Netherlands, conducted intensive research into this. Their findings revealed astonisihining results: while one-third of the genes are shared among all brassica crops, half are unique to specific crop types, being absent in others.
“B. oleracea has many genes. Cauliflower, for example, has some 60 thousand genes, compared to humans who have only 20 thousand. This is due to the fact that the genome tripled some fifteen million years ago, while the original genome was already sufficient to enable the plant to function successfully. We aim to understand what prompted the variation so that we can breed to create better varieties”, explained Bonnema.
Researchers of the study indicated that more than half of the genome consists of transposons, which are made up of tiny parts of DNA that ‘jump around’ inside the genome and, as a consequence, may be seen in any number of locations within it. The transposons are also referred to as “jumping genes” in the Netherlands. The researchers further indicated that their reputation among humans for leading to diseases that include haemophilia, whereas for plants they make up an essential form of natural variation.
“We discovered that the transposons frequently regulate the activity of genes in their vicinity by increasing or decreasing the activity levels. Previously, we were looking for the uniquely defining genes that determine what makes a cauliflower a cauliflower. Now we know that you must find not only the genes but also their operators. The transposons, in this case. They are the on/off switches and regulators of the genes that are in their vicinity”, she says.
Researchers of the study pointed out that this was significant Progress in understanding. With the availability of a pan-genome, which provides a comprehensive overview of all genes within a species, scientists can now effectively classify transposons and other structural variations. These transposons play a pivotal role in regulating gene activities, impacting not only the genes responsible for the distinct traits of various brassica vegetables but also those crucial for resistance, flavor, nutritional content, and resilience to environmental conditions. For instance, cauliflower exhibits high temperature sensitivity. By comprehending the mechanisms underlying this sensitivity, breeders can develop varieties with improved tolerance to temperature fluctuations, as elucidated by Bonnema.
