Chitwood, Ph.D., and his research group at Donald Danforth Plant Science Center in St. Louis, are studying the nature of structure and form in plants using the smallest single-celled organism in the world, an aquatic algae called Caulerpa taxifolia. A recent article published in the online journal PLOS Genetics details their work on the subject. The Caulerpa is a unique organism, according to This is a plant which belongs to the group of green algae. A single cell in this organism can grow to a length of 6 to 12 The organs of the land plant have evolved independently into a form that is like the plants’. stem is a small projection of the cell which grows along a surface and becomes a leaf-like frond and a root like holdfast, from which it is anchored and absorbs It is amazing how many structures are composed of just one cell.” “For many years, I have been fascinated by structure and form in plants, specifically in tomato, the land plant that I have studied most,” Chitwood said. In a complex tomato plant with so many parts and forms, it is obvious it is a daunting task to discover what determines structure and form. In order to build more effective tools to improve plants and ultimately make food production more reliable, we must understand how plants grow and develop. Agricultural crops have complex architectures because multicellularity is an important prerequisite. Caulerpa is also a plant, and it also evolved with a land plant-like body plan, but without multicellularity, and with just one “How can that be?” Chitwood and his group suggested that the structure of Caulerpa might be reflected in the RNAs present in various areas For example, the frond part of the cell might show different RNAs from the holdfast part of the cell (RNA’s are the molecules that are produced when genes are expressed). By performing this type of analysis on Caulerpa, you may also gain insight into the distribution of RNA within single cells, which would normally be difficult to accomplish in small cells of multicellular organisms.

The results of this study were even more interesting than we had imagined,” The RNA expression patterns within different parts of the Caulerpa cell resemble those of multicellular organs of tomato, but there is also a correlation between the RNA expression patterns expressed within these regions of the Caulerpa cell and those expressed within “While the lineage that Caulerpa belongs to probably diverged from the one whose descendants are land plants more than 500 million years ago, Caulerpa displays patterns of RNA accumulation that are not so different from the ones that plants have today,” “Land plants can appear with and without multicellularity, so it’s clear that the basic form we associate with land plants can arise in either way. The plasmodesmata of higher plants connect them to one another, and some researchers have suggested that multicellular land plants may exhibit properties similar to those of single-celled species such as How would it change our understanding of higher plants, like tomato, if we could really see them as one cell instead of many? We believe that multicellular land plants, like tomato, and giant single-celled algae, like Caulerpa, may have a pattern of RNA accumulation in common just as we have evidence of an RNA accumulation pattern shared by both. We have been forced to evaluate plant structure from an entirely different perspective as a result of our findings, and that is the most valuable outcome from this research.