Ανάπτυξη του φασολιού. Θα συζητήσουμε στη διάλεξη τα πιό σημαντικά τμήματα και φάσεις της ανάπτυξης.
Ταξιδεύοντας μέσα στο φύλλο
Ξύλωμα και φλοίωμα
Ανάπτυξη ανθικών μερών
Lens, F., Tixier, A., Cochard, H., Sperry, J.S., Jansen, S. and Herbette, S. (2013). Embolism resistance as a key mechanism to understand adaptive plant strategies. Curr. Opin. Plant Biol. 16: 287-292, with permission from Elsevier.
Parcy, F., Bomblies, K., and Weigel, D. (2002). Interaction of LEAFY, AGAMOUS and TERMINAL FLOWER1 in maintaining floral meristem identity in Arabidopsis. Development 129: 2519–2527.
Wils, C.R. and Kaufmann, K. (2017). Gene-regulatory networks controlling inflorescence and flower development in Arabidopsis thaliana. Biochim. Biophys. Acta – Gene Regul. Mech. 1860: 95–105.
Dornelas, M. C. and Dornelas, O. (2005). From leaf to flower: revisiting Goethe’s concepts on the ¨metamorphosis¨ of plants. Braz. J. Plant Physiol. 17: 335-344 CC-BY.
Post-embryonic development refers to the developmental processes that occur after an organism has completed its embryonic stage. In most animals, post-embryonic development involves a series of changes that lead to the formation of adult structures and the attainment of reproductive maturity.
The specific processes involved in post-embryonic development vary widely between different organisms. In some animals, such as insects, post-embryonic development involves a process called metamorphosis, in which the larval form transforms into the adult form. In other animals, such as humans, post-embryonic development involves a gradual growth and maturation process.
During post-embryonic development, many different types of tissues and structures can form, including muscle tissue, bone tissue, nervous tissue, and reproductive structures. Hormones and other signaling molecules play important roles in regulating post-embryonic development.
Overall, post-embryonic development is a complex and dynamic process that is essential for the growth, maturation, and reproduction of all animals.
Xylem is a type of plant tissue that is responsible for transporting water and dissolved minerals from the roots to the rest of the plant. It is a complex tissue made up of several different cell types, including tracheids, vessel elements, and parenchyma cells.
Tracheids and vessel elements are elongated, tube-like cells that form long, continuous channels through which water can flow. These cells have thick, lignin-rich walls that help to support the plant and prevent the collapse of the xylem tissue under the weight of the water it contains.
Parenchyma cells, on the other hand, are relatively unspecialized plant cells that play a supportive role in the xylem tissue. They are responsible for storing and distributing nutrients and other essential molecules throughout the plant.
The xylem tissue is critical for maintaining the water balance and nutrient uptake of the plant. As water is absorbed by the roots, it travels through the xylem tissue and is distributed to the rest of the plant. The xylem also plays a role in the transportation of minerals and other essential nutrients, which are taken up by the roots and transported through the xylem to other parts of the plant.
Overall, the xylem tissue is essential for the survival and growth of all plants, providing a critical pathway for the transportation of water, minerals, and other essential nutrients throughout the plant.
The ABC model
The ABC model for flower development is a widely accepted model that explains the genetic regulation of floral organ identity in plants. According to this model, the development of floral organs is regulated by three classes of genes: A, B, and C.
Class A genes, including APETALA1 (AP1), are responsible for the development of sepals and petals. When these genes are expressed in the outer two whorls of the developing flower, they promote the formation of sepals in the first whorl and petals in the second whorl.
Class B genes, including APETALA3 (AP3) and PISTILLATA (PI), are responsible for the development of petals and stamens. When these genes are expressed in the second and third whorls of the developing flower, they promote the formation of petals in the second whorl and stamens in the third whorl.
Class C genes, including AGAMOUS (AG), are responsible for the development of stamens and carpels. When these genes are expressed in the third whorl of the developing flower, they promote the formation of stamens. When these genes are expressed in the fourth whorl, they promote the formation of carpels.
The ABC model suggests that the formation of each floral organ is determined by the combination of gene expression in each whorl. For example, in a typical flower, the outermost whorl expresses class A genes, the second whorl expresses class A and B genes, the third whorl expresses class B and C genes, and the innermost whorl expresses class C genes. This combination of gene expression leads to the formation of sepals, petals, stamens, and carpels in the appropriate whorls.
Overall, the ABC model has been useful in understanding the genetic basis of flower development in plants and has provided insight into the evolutionary origins of the diversity of floral structures observed in different plant species.
The stem is an essential part of the plant that provides structural support and plays a critical role in transporting water, nutrients, and other essential molecules throughout the plant. It is typically the above-ground part of the plant that connects the roots with the leaves, flowers, and other reproductive structures.
The stem is made up of different tissues, including the epidermis, cortex, vascular bundles, and pith. The epidermis is the outermost layer of the stem and serves as a protective layer against physical damage, pests, and pathogens. The cortex is a layer of ground tissue that lies beneath the epidermis and is involved in the storage of nutrients and water. The vascular bundles, which are composed of xylem and phloem tissues, are responsible for transporting water, nutrients, and other essential molecules throughout the plant. The pith is a central region of the stem that is often involved in storing nutrients and water.
The stem also contains nodes and internodes, which are specialized regions of the stem. Nodes are the regions of the stem where leaves, branches, and other structures are attached, while internodes are the regions of the stem that lie between the nodes.
In addition to providing structural support and facilitating the transport of essential molecules throughout the plant, the stem also plays a critical role in the growth and development of the plant. The stem contains meristematic tissue, which is responsible for generating new cells and facilitating growth and development in the plant. The stem also plays a role in phototropism and gravitropism, which are the plant’s ability to grow towards or away from light and gravity, respectively.
Overall, the stem is a critical part of the plant that plays a variety of essential roles in plant growth, development, and survival.