Duckweed, also known as Wolffia, is the fastest-growing plant in the world, but the genetics that explain this amazing feat have long been a mystery. Plant scientists now know how it’s able to grow so fast based on details of its genome.

It is wrong to say that duckweed is the fastest-growing plant known to science. Scientists are still uncertain as to how this strange little plant can become so successful. Thanks to advances in genome sequencing, researchers are now discovering whether the plant is unique and, by doing so, finding out about aspects of plant biology and growth in the process. New findings led by scientists at the Salk Institute about how a plant’s genome enables it to grow so rapidly have been published in the February 2021 issue of Genome Research. They explain how plants make trade-offs between growth and other functions, such as roots and pest defenses. The findings of this study can contribute to designing entirely new manufacturing plants that are optimized for specific uses, such as carbon storage that will be effective in addressing “Many advances in science have been made possible by organisms that are simple, like yeast, bacteria, and worms,” says Todd Michael, first author of the study and professor in Plant Molecular and Cellular Biology Laboratory at Salk Institution for Biological Studies. The idea is to use an incredibly tiny plant like Wolffia to learn what makes plants tick. It appears like tiny floating green seeds, and each plant is not much bigger than a pinhead. Wolffia grows in fresh water on every continent except Antarctica. An anonymous plant does not have roots and only consists of one leaf and stem structure. In a similar process to yeast, it reproduces when a daughter plant buds off from its Scientists believe that Wolffia, which can double in just one day, could become an important source of protein to feed the growing population of the Earth. (It is already eaten in parts of Southeast Asia, where it refers to as khai-nam, which translates to “water eggs.”.)

Researchers grew Wolffia under light/dark cycles to discover how the gene expression is altered as the day progressed, as well as which genes are active in various stages of the day, in order to understand how it generates such rapid growth. (An important aspect of plant growth involves light and dark cycles, with most of the growth occurring in the morning.) “It was surprising to learn Wolffia only has half the number of genes that are regulated by light/dark cycles compared to other plants,” Michael remarks. We believe this is why the plant grows so fast, as it lacks the regulations that limit when it can grow. The scientists also found that genes associated with other important elements of plant behavior, such as defense mechanisms and root growth, were absent. Michael says that the plant has shed most of the genes it no longer requires. It appears to have evolved to focus only on fast growth.” “We can gain valuable insight into how plants develop their body plan and how they grow from the Wolffia genome,” says Professor Joseph Ecker, HHMI Investigator and director of Salk’s Genomic Analysis Laboratory. “I believe that this plant will become a model for studying plant behavior, including how genes contribute to various biological processes.” One focus of Michael’s lab is learning how to develop new plants from the ground up, so that they can be optimized to perform a particular task. A study is now underway that offers potential for improving crops and agriculture, as well as expanding basic knowledge of plant biology. using Salk’s Harnessing Plants Initiative to optimize plants to store carbon from the atmosphere, scientists can address the threat of climate change by helping plants store more carbon in their roots. Using a simplified plant to understand the networks that control fate, Michael plans to continue studying Wolffia in order to gain a deeper understanding of genomic architecture in plant development.