Asparagus and orchids share surprising similarities

Researchers have unveiled a fascinating connection between asparagus and vanilla orchids, very different plants in every way, highlighting the unexpected similarities in the composition of their cell walls.

This discovery, shared in a new study from the University of Copenhagen, forms part of a larger endeavor that has culminated in the creation of a comprehensive “reference catalog” of plant cell wall compositions, covering 287 species across the plant kingdom. 

The research, led by botanist Louise Isager Ahl of the Natural History Museum of Denmark and Professor Peter Ulvskov from the Department of Plant and Environmental Sciences, sheds new light on the intricate world of plant biology.

The findings have profound implications for agriculture, environmental conservation, and our understanding of plant evolution.

Importance of plant cell walls

The focus of this research was the plant cell wall, a crucial structure that provides mechanical support and facilitates water transport within plants, much like skeletons do for humans. 

“Flowering plants have succeeded in adapting to the most unwelcoming and harshest environments in the world, in part due to the construction of their cell walls. They provide the plants with both mechanical structure and ensure the internal transport of water. Plant cell walls are composed of many different carbohydrates, that each have a unique structure and function — you can think of them like toy building blocks.” said Isager Ahl.

“Although humans rely heavily on plants and their carbohydrates for food, building materials, clothing and medicine, our knowledge of their fine structure is still quite limited. We know that carbohydrates are some of the most complex chemical structures in nature, but how they are assembled, how they work and how they have evolved over the past several million years is still largely unknown.”

The role of genetics 

To investigate, the researchers analyzed leaf and stem tissues from 287 different plant species. The goal was to gain a better understanding of the relationship between the ultra-complex carbohydrates in plant cell walls and the plants’ evolutionary trajectories, growth forms, and habitats.

Contrary to the researchers’ initial hypothesis, which suggested that environmental factors might influence cell wall structure, the study revealed that genetic heritage plays a more significant role. 

“As an example, in a typical Danish beech forest, you will find beech trees, anemones, various grasses, and other plants. Since they share the same habitat, it would be easy to think that their construction is also similar,” explained Isager Ahl.

“However, our analyses show that the carbohydrate compositions of their cell walls are vastly different. And when we compare carbohydrate compositions with the plants’ family history, habitat and growth form, we can see that it is primarily their family history that determines their individual structures.”

“The carbohydrate composition of a plant is thereby more closely related to where it is placed in a family tree than to its habitat and growth form. Here, heritage plays a more important role than environment,” noted Professor Peter Ulvskov.

Targeted breeding programs 

This revelation has far-reaching implications, particularly in the realm of plant breeding. The comprehensive catalog of cell wall compositions developed by the team could serve as a vital resource for targeted breeding programs aimed at enhancing the quality and sustainability of crops. 

“Even though the cell walls of plants are an important component in our food, animal feed, textiles and other materials, we have yet to target our breeding of cultivated plants to improve their cell wall properties,” said Professor Ulvskov.

“For example, cell walls determine to a large extent the digestibility of plant material. Targeted breeding of cell walls could increase both the quality and sustainability of animal feed. Now there is a catalogue to start from.”

Plant cell walls and climate resilience 

According to the researchers, their dataset is ideal for research into climate-resilient plants.

“Our data can be used as an encyclopedia or reference database for researchers when they, for example, want to plan a study on a plant group they have not previously worked on,” said Isager Ahl.

“For example if you want to study how plant species in the rainforest, desert or on the heath react to environmental influences such as drought, high CO2 levels or floods – the dataset can be used as a benchmark.”

This type of knowledge is increasingly relevant as climate change alters plant habitats.

“All of the climatic and environmental changes that we are now facing are challenging the planet’s plants, and thus humans as well. Because we are deeply dependent on how plants function,” said Professor Ulvskov.

“If we are going to develop more resilient plants, it is important that we understand the mechanisms by which they survive or succumb. Here, understanding their building blocks, in the form of cell walls and carbohydrates plays a key role.”

The study is published in the journal Plant Cell & Environment.

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