Studying the DNA of Herbarium Specimens

By Barbara M. Thiers, Nicole Tarnowsky

Sep 20 2019

Molecular biologists study the DNA of plants. They use this data to identify specific genes that are responsible for traits in a plant such as the development of flowers of different colors, or fruits of different types. Although a researcher would probably opt for using DNA from living material if possible, extraction from herbarium specimens may be the only option for species that are rare or extinct in the wild and are known now only from herbarium specimens.

New and more powerful tools for sequencing DNA, known as Next Generation Sequencing are yielding even richer information from specimens. Surprisingly, herbarium specimens are well-adapted to this finer-grained approach, because in preparing DNA for genomic analysis, the first thing one has to do is break the strands into small pieces – the condition that already exists in dried specimens. The area of study known as genomics uses this more detailed genetic information to map functions to gene sequences, that is, to identify a set of sequences that controls a particular function in an organism.

Using these genomes, breeding programs can be developed to improve the hardiness of economically important plants and protect them from an increasingly drastic climate. For example, researchers have looked at the wild relatives of corn and other crops to study tolerance to drought, salinity, waterlogging, insects, and disease.

Another interesting study is identifying gene sequences responsible for nitrogen fixing in some plants. Most plants absorb nitrogen from the soil which in the case of crop plants gets depleted, forcing the need for fertilizers. Some plant species though are able to metabolize nitrogen from the air. If those traits can be used in other crop plants it would cut down the need for fertilizers and their damaging run off into water systems.

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