Blueprint explains how plants build a transport lane for sugar
At the root tip of a small area, it has been found to be responsible for organizing the growth and development of a complex vascular tissue network that transports sugars through the roots of plants.
In an article published today in Science, an international team of researchers presents a detailed plan for how plants build phloem cells – the tissue responsible for transporting and collecting sugar and starch to the parts of the plant we collect (seeds, fruits and tubers). ) to feed much of the world.
This pivotal study reveals how global signals in the root meristem coordinate the distinct maturation stages of phloem tissue.
Phloem is a highly specialized vascular tissue that forms an interconnected network of continuous filaments throughout the body of a plant. It carries sugars, nutrients and various signaling molecules between leaves, roots, flowers and fruits.
As a result, the phloem is central to plant function. Understanding the emergence and evolution of the Floem network is important for future applications in agriculture, forestry and biotechnology, as it can reveal how this sugar energy can be better transported where it is needed.
How do plants build a sugar lane on a multi-lane highway?
The roots of the plant will continue to grow throughout the life of the plant. This phenomenon, known as vague growth, means that the roots are constantly lengthening as they add new tissue to the tip of the root – such as building an endless highway. A continuous file of specialized phloem cells, running along the length of the roots (analogous to the highway band), delivers the main nutrient, sucrose, to those parts of the plant where it is needed for growth. To fulfill this important function, the phloem tissue must develop and mature rapidly to be able to supply sugars to the surrounding tissues – in the same way as the construction of the maintenance lane, which must be completed in the first phase of multi-lane highway construction.
A problem that has long confused botanists is how a single instructive protein gradient can organize the construction steps in different specialized cell files at all roots (highway lanes). How one cell type reads the same gradient as its neighbors but interprets it differently as a step in its own specialized development is a question that botanists have sought to address.
For the past 15 years, researchers Yrjö Helariutta’s teams at University of Cambridge and university of Helsinkihave revealed the central role of intercellular communication and the complex feedback mechanisms involved in vascular patterning. This new study, conducted in collaboration with the University of New York and North Carolina State University, reveals how this single phloem cell is constructed independently of the surrounding cells.
The Sainsbury / Helsinki group dissected each step in the construction of a floem cell file (sugar transport pathway) in the Arabidopsis thaliana model plant using unicellular RNA-seq and live imaging. Their work showed how the proteins that regulate the broad maturation gradient of the root interact with the genetic machinery that specifically regulates the development of phloem.
This is one mechanism that appears to help the phloem cell file to accelerate maturation by using its own machinery to interpret maturation cues. Dr. Pawel Roszak, the first author and researcher of the study Sainsbury Laboratory Cambridge University (SLCU), explains: “We have shown how global signals in the root meristem interact with cell type – specific factors to determine distinct phylemic development stages by cell resolution.
The group also showed how phloem evolution progresses over time, with early genetic programs blocking late genetic programs and vice versa – just as road asphalt working groups hand over construction to lane species in the latter stages of highway construction. In addition, they showed how early phloem regulators instructed certain genes to divide phloem cells into two different subtypes – such as building a fork into two distinct targets.
The second director of the work, Professor Yrjö Helariutta, said that the reconstructed steps of his groups from birth to the terminal separation of protofloem at the root of Arabidopsis revealed stairs. Helariutta said, “The development of a floeme requires a broad maturation gradient that interacts with cell type-specific transcriptional regulators to stage cell differentiation.”
“Combining unicellular transcriptomics and live imaging, we have here mapped cellular events from the emergence of a floemic cell to its terminal differentiation into floemic cellular cells. This allowed us to reveal the genetic mechanisms that coordinate cell maturation obvious “fail-safe” mechanisms ensured displacements.
Researchers intend to further investigate the evolution of these mechanisms and whether these steps will be repeated in other areas of plants and other plant species.
Article reference
Pawel Roszak, Jung-ok Heo, Bernhard Blob, Koichi Toyokura, Yuki Sugiyama, Maria Angels de Luis Balaguer, Winnie WY Lau, Fiona Hamey, Jacopo Cirrone, Ewelina Madej, Alida M. Bouatta, Xin Wang, Marjorie Guichard, Robertas Ursache, Hugo Tavares, Kevin Verstaen, Jos Wendrich, Charles W. Melnyk, Yoshihisa Oda, Dennis Shasha, Sebastian E. Ahnert, Yvan Saeys, Bert De Rybel, Renze Heidstra, Ben Scheres, Guido Grossmann, Ari Pekka Mähönen, Philipp Denninger, Berthold Göttgens , Rosangela Sozzani, Kenneth D. Birnbaum, Yrjö Helariutta(2021) Cell-specific dissection of phloem development combines a maturation gradient with cell specialization, Science
DOI: 10.1126 / science.aba5531
Sainsbury Laboratory Cambridge University: https://www.slcu.cam.ac.uk/
Sainsbury Laboratory Cambridge University (SLCU) is a botanical research institute funded by Gatsby Charitable Foundation. The SLCU focuses on increasing understanding of the regulatory systems underlying plant growth and development, and brings together experts in the biological, physical, and mathematical sciences, combining a variety of wet laboratory experimental studies with computational modeling. This interdisciplinary approach is necessary to understand the complex dynamic and self-organizing properties of plants. Sainsbury Laboratory has 13 research teams focusing on fundamental plant biology for the long-term sustainability of the supply of food and other plant products such as fuel, fiber and building materials.
University of Helsinki: https://www.helsinki.fi
The University of Helsinki is Finland’s largest and oldest university and an innovative center for science and thinking. The university has been an integral part of the birth of the Finnish national identity and the welfare state since 1640. Over the years, the academic community has grown to 40,000 people scattered to 11. faculties on four campuses.
The university’s strategic plan is currently emphasizing four research themes: the well-being of people and our environment, a human and just world, a sustainable future for our planet and the possibilities opened up by boundless curiosity – a universe of ideas and possibilities.