Plant cells are immobile, encased in a rigid cell wall. Unlike animal cells, migration and programmed cell death play little role in the patterning of plant cell fates, nor can they move when their environment changes. If the supply of food is low or if there is a predator, animals can move, fight or fly. But plants cannot. They have to adapt constantly to their environment and their development is highly plastic. Animal development is mainly embryonic: the body shape is defined during embryogenesis and the adult derive from the enlargement of the embryo. In contrast, in plants, most of the development occurs post embryonically and never ceases. In fact, because plants can't escape from their physical locations, they adapt and "escape" through development. When there is a lack of nutrients or energy, the plant develops its root system to explore the ground or its aerial system to get some light. Under attack from a pathogen or herbivore, the plant is able to synthesise signalling molecules to change its development and defend itself.
Despite their sessile lifestyle, plant development is highly plastic, due to the important role of information exchange between neighbouring plant cells. It appears that cell are more dependent on their positional information rather than lineage origine as in animals. Almost every plant cell containing nucleus has been shown to be able to re-enter the cell cycle and divide. This occurs for example after wounding, neighbouring cells are able to divide and differentiate to replace dead cells.
In normal plant development, post embryonic growth comes from meristems. Meristem is a type of embryonic tissue in plants consisting of unspecialised, youthful cells called meristematic cells and found in areas of the plant where growth is or will take place - the roots and shoots. Meristematic cells are small isodiametric cells, the nuclei occupy most of the cell. The cytoplasm contains undifferentiated plastids and posses a small vacuole.
Pool of cells are kept meristematic and divide, cells exiting the meristematic zone, start elongating and then differentiating.
We’ll look at some of these unusual features of plant development using examples from the model plant, Arabidopsis thaliana.
Arabidopsis thaliana, a model plant for plant sciences
Arabidopsis thaliana grows quickly, produces prolific seed, and is easy to transform. Its genome is completely sequenced and a large variety of experimental tools and genetic resources are available. This made the plant become one of the favourite tool of plant scientists.
A review. Coming soon!!! This article is currently under development and should not be considered accurate yet.
- Overview of the Arabidopsis seedling
- Overview of the root
- Developmental zones
- Cell initials
- Structure of the meristem
- Primary vs lateral roots (embryonic vs post-embryonic origin)
- Hormones in the Arabidopsis seedling root
- Biotic and abiotic factors affecting root development
A little review with some references for plant science applications
Mainly Plant Molecular Biology and Development
Plant Physiology Online (2002)
This site is a good general introduction to learn about plant biology. There is an edited version of the Plant Physiology book which is far more developed, with very nice figures to illustrate the science. If you are seriously interested in plant biology, it is strongly recommended that you get it from a library or buy it.
a companion to Plant Physiology, Third Edition by Lincoln Taiz and Eduardo Zeiger, published by Sinauer Associates.
ABOUT THE SITE
This site provides a wealth of additional material to accompany the textbook. Much of the content is referenced in the textbook (as well as listed at the end of each chapter), but the site is a continuously growing resource, so check back regularly to see what new material has been added.
There are four main categories of content on the site:
1. Web Topics: This is material that adds to the coverage in the textbook. Topics include text, figures, and tables, and are referenced throughout textbook (and also listed at the end of each chapter).
2. Web Essays: These are original articles on various topics related to each chapter, written by experts in the field.
3. Study Questions: These short answer-style questions are designed to help you learn the key concepts covered in each chapter, and apply them to problems.
4. Readings: Suggested readings for further study.
Topics covered :
- 1. Plant Cells
- 2. Energy and Enzymes
- 3. Water and Plant Cells
- 4. Water Balance of Plants
- 5. Mineral Nutrition
- 6. Solute Transport
- 7. Photosynthesis: The Light Reactions
- 8. Photosynthesis: Carbon Reactions
- 9. Photosynthesis: Physiological and Ecological Considerations
- 10. Translocation in the Phloem
- 11. Respiration and Lipid Metabolism
- 12. Assimilation of Mineral Nutrients
- 13. Secondary Metabolites and Plant Defense
- 14. Gene Expression and Signal Transduction
- 15. Cell Walls: Structure, Biogenesis and Expansion
- 16. Growth and Development
- 17. Phytochrome and Light Control of Plant Development
- 18. Blue-Light Responses: Stomatal Movements and Morphogenesis
- 19. Auxin: The Growth Hormone
- 20. Gibberellins: Regulators of Plant Height
- 21. Cytokinins: Regulators of Cell Division
- 22. Ethylene: The Gaseous Hormone
- 23. Abscisic Acid: A Seed Maturation and Anti-Stress Signal
- 24. The Control of Flowering
- 25. Stress Physiology
To get access to the above topics : http://4e.plantphys.net/categories.php?t=t
The Arabidopsis Book
Description: Edited by Chris Somerville and Elliot Meyerowitz. Co-edited by Jeff Dangl and Mark Stitt. An Open Access electronic book, The Arabidopsis Book (TAB), is an attempt at a new mode of communication between researchers and a new model for scientific publishing. TAB in its initial stage is a compilation of over 100 invited chapters, each reviewing in detail an important and interesting aspect of the plant Arabidopsis thaliana, with reference to what is known in other plants and in other kingdoms. Each set of authors has agreed that their chapter can be kept up-to-date either by the original authors or by others. TAB will therefore be a dynamic information resource that will evolve with the state of knowledge. We envision evolution of the format as well as the contents - initially by taking advantage of the Web-based possibilities of hyperlinks, which will be added to cross-reference gene names and references to other chapters, and which will eventually lead from each gene and sequence reference to sequence databases, and from each paper cited to its abstract. The Arabidopsis Book is therefore envisioned as a complementary resource to the many databases that contain specific information about Arabidopsis, including The Arabidopsis Information Resource. It is our hope that this book will be broadly useful and, more generally, that it will facilitate the development of new web-based tools for dissemination of knowledge. TAB will be available only via the Internet and will be available free of charge. The American Society of Plant Biologists will provide funds for the mounting and maintenance of the book on the Internet as a public service. Electronic URL: http://www.aspb.org/publications/arabidopsis/
Lectures and virtual journal club from Jen Sheen's lab (Harvard University)
PowerPoint Presentations: http://genetics.mgh.harvard.edu/sheenweb/courses/genetics300.html
- Circadian Rhythms in Plants
- by Elena Baena Gonzalez
- Ethylene Signaling in Plants
- by Sang-Dong Yoo
- SAR Signaling
- by Wisuwat Songnuan
- Plant Root Endosymbioses
- by Ethan Levesque
- miRNAs and other RNAi-related factors
- functions in plant and animal gene regulation and development
- by Gabriel Hayes
Jen Sheen's lab give access to its virtual journal club, where they provide every month a list of papers of particular interest, with comments. http://genetics.mgh.harvard.edu/sheenweb/virtual_journal.html
Other websites of interest
- Ben Scheres (University of Utrecht) is quite famous in plant biology and his website is a good start to learn about root anatomy and development
- General Biology tutorial
- Scott Russell (Department of Botany and Microbiology of the University of Oklahoma) post Botanical Links every month on his website
- Tutorial Material for Botanists. This page is under constant improvement. It is part of the Israeli Society of Plant Sciences site It includes links to sites related to teaching all aspects of botany.
Some websites talking about plant cells (we can use these example to do a similar tutorial):