What is Plant Biology?

What have plants ever done for us?

As a species we are dependent on the natural environment to provide our basic needs; in turn, we have shaped it to better serve our requirements. With the challenges of adapting to a changing global climate, while providing food and fuel for a growing global population, the study of plants is as relevant as it has ever been.   

With origins in scavenging for food and materials, plant science has grown to include a wide range of disciplines from Botany to Synthetic Biology. Today the study of plants continues to capitalize on the unique advantages of plant systems and has contributed to the understanding of topics ranging the laws of genetic inheritance to RNA silencing.

Human impacts on plants

Throughout history, we have modified plants to better serve our needs. For example, Corn (Zea mays) is a believed to have been domesticated in the Balsas river valley in Mexico around 9,000 years ago. Selective breeding of Z. mays ssp. parviglumis, referred to as Teosinite (a name of Nahuátl Indian origin that actually refers to a group of four wild grasses), resulted in a remarkable transformation in plant morphology that improved yield, digestibility and ease of cultivation.

maize-teosinte
An image depicting Teosinte, Maize-teosinte hybrid, Maize. Source: John Doebley

Such was the achievement that corn became of central importance to local societies, as reflected in the Mayan creation story Popol Vuh: after failed attempts to create humans using mud or wood, the gods used cornflour.

Work on maize improvement continues in Mexico today, at the International Maize and Wheat Improvement Centre (CIMMYT) which runs a breeding program and maintains a germplasm of over 28,000 unique seed varieties.

In addition, since the mid 1990s, conventional breeding of corn has been supplemented by genetic modification to introduce traits not found in natural populations, such as resistance to pests and herbicides. One of the most successful approaches has been to introduce genes from the bacterium Bacillus thuringinesis that can prevent worm infections from devastating harvests.

Human impacts on the environment

As well as altering plants for our needs, we have shaped the environment to grow them. A stunning example comes from the Inca civilization which used thousands of years of knowledge to build canals and terraces in order to boost agricultural output in the Andes. Depicted are the ruins at Moray in Peru, thought to have been an agricultural research station, there exists a large temperature differential between the top and bottom of the terraces, each ring has its own microclimate and may have been used to adapt varieties to different environments.

moray_-_qechuyoq
By Philipp Weigell – picture taken by Philipp Weigell, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=3922489

A cautionary tale is provided by farming in the US midwest. Once covered in a vast tallgrass prairie, European settlers cleared vegetation to take advantage of the deep fertile soils for the production of crops and grazing cattle. The midwest is now one of the most productive and intensive farming systems in the world. Combined improvements in agronomy and varieties, including the adoption of chemical fertilizers, hybrids and have led to an ~9 fold increase in corn yields since the 1930s.

CornYieldTrend_US.gif
Source: https://www.agry.purdue.edu/ext/corn/news/timeless/yieldtrends.html

However, the high yields have also come at an environmental cost. Much of the area is dominated by only two crops, maize and corn. The effects of this monoculture can include a decrease in pollinator and bird numbers, soil erosion and water runoff. In addition, over application of nitrate fertilizers is widespread in the region, nutrients drain into the Mississippi river ending up in the Gulf of Mexico. This concentration of nutrients results in harmful algal blooms killing off aquatic life.

Uses of Plants

We are dependent on plants for many of our everyday needs. Maize again is a helpful example: the biomass is used for everything from popcorn to bourbon to gypsum wallboard! We can make food, fibers, and fuel from it, every part of the plant is used. If you were to go down to your local Walmart and check each product to see if it contains corn, you will likely count several thousand items in total!

Medicines are the fourth major category of products we get from plants. Corn steep liquor can be used indirectly in the production of antibiotics, by providing nutrients for growth of bacteria and fungi used in industrial fermentation, but there are also three direct ways we can get medicines from plants:

  1. Many medicinal compounds are made by plants, for example, Artemisinin, which is extracted from Artemisia annua (sweet wormwood) and used to treat malaria. The story of its discovery is a fascinating tale that highlights the advantages of bringing together two medical traditions: Artemisinin was identified by a team of researchers led by Tu Youyou, who combined western chemistry, interviews with practitioners of traditional Chinese medicine and information from a 3rd-century Chinese medicinal manual to produce an effective antimalarial. This drug has saved millions of lives, and in 2015 Tu Youyou became the first Chinese women to win the Nobel Prize for her efforts. I highly recommend watching her acceptance speech for the full story.
  2. Plants can also provide the raw materials for the synthesis of compounds with medicinal use. A great example of this is the pioneering work of American Chemist Percy Lavon Julian who battled racial prejudice throughout his career, and went on to developed a process for chemical synthesis of steroids such as estrogen, progesterone and testosterone from soy oil, compounds which were previously extracted from animal spinal cords in a much more costly procedure.
  3. We are now entering an era where the genetic information from plants can be used for the synthesis of drugs. In 2015 researchers announced the first synthesis of opioids in yeast Saccharomyces cerevisiae. Conventionally, opioids accumulate in seeds of the opium poppy (Papaver somniferum), and there is a long tradition of cultivation for extraction. Yeast strains were generated after years of painstaking research to identify all the enzymes involved in opioid synthesis, these enzymes were then cloned and expressed in yeast. Although titers are still low, this work opens up the possibility of using, and potential production of novel opioids by altering the combination of enzymes expressed in yeast. [fun fact: be careful not to eat too much Poppy seed cake in one go – you can fail a drugs test!]

Botany as a Science

Every culture contains knowledge of the local flora and fauna and some of the first records of classifying plants can be found in Indian Vedic texts over 3,000 years ago. Botany has subsequently grown into a variety of subdisciplines, including everything from plant biochemistry to ecology.

Barbara_McClintock_(1902-1992)_shown_in_her_laboratory_in_1947.jpg
By Smithsonian Institution/Science Service; Restored by Adam Cuerden – Flickr: Barbara McClintock (1902-1992) Smithsonian original, Public Domain, https://commons.wikimedia.org/w/index.php?curid=25629182

The blog post is far too short to mention all the ways the study of plants has contributed to our wider understanding, but some notable examples include giving birth to cell biology, defining the laws of genetic inheritance, by Czech monk Gregor Mendel, who investigated how traits are passed through generations using garden peas. Barbara McClintock’s discovery of transposable elements through analysis of Maize, and identification of RNA interference in the 1990s which was aided by analysis of patterning in Petunia flowers.

Links of interest

Recommended popular science books


Many thanks to all the people who made suggestions for constructing this piece, including: Anne Viscomi; Debra Santo; Tomas Moravec Liv Lanberg Ian Ramjohn Rakesh Tomar Herman van loon Sean Haughian Noah Winters Schornack CS Prakash, Rob Last, Liz Haswell, James Lloyd, Devang Mehta and Dale Artho

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