What are the 5 stages of embryonic development in plants?
The zygote produced after fertilization must undergo various cellular divisions and differentiations to become a mature embryo. An end stage embryo has five major components including the shoot apical meristem, hypocotyl, root meristem, root cap, and cotyledons.
What is pattern formation during embryogenesis?
In developmental biology, pattern formation describes the mechanism by which initially equivalent cells in a developing tissue in an embryo assume complex forms and functions. Embryogenesis, such as of the fruit fly Drosophila, involves coordinated control of cell fates.
How is vascular tissue arranged in a leaf?
In leaves, the vascular bundles are located among the spongy mesophyll. The xylem is oriented toward the adaxial surface of the leaf (usually the upper side), and phloem is oriented toward the abaxial surface of the leaf.
What is pattern formation in plants?
Pattern formation—the generation of regular differences in space — occurs at several levels of organization. For example, a particular group of cells at the shoot apex may receive a signal to form a leaf. The leaf will get a polarity, developing an upper and a lower side.
What are the 6 stages of embryonic development in order?
What genes are involved in pattern formation?
It has been revealed that many homeobox genes play an important role in the various stages of pattern formation in early embryogenesis. After fertilization, the maternal genes (e.g., bicoid) establish the embryonic axis and polarity by the gradient of their gene products.
How does the arrangement of vascular tissues in the root differ from those in the stems?
Vascular tissue is organized into discrete strands called vascular bundles, each containing xylem and phloem. In stems, the vascular tissue is organized into many discrete vascular bundles. In the roots, the vascular tissue is organized within a single central vascular cylinder.
Why is the vascular tissue arranged in bundles?
Xylem vessels are tough and strong, so the vascular bundles are in the centre of the root to resist forces that could pull the plant out of the ground.
What genes control pattern formation?
What are some kinds of events that contribute to pattern formation?
- Self-assembly of large molecular structures.
- Organized cell growth and cell architecture.
- Control of cell proliferation.
- External cues.
- Stochastic assignment of cell fate.
- Asymmetric cell divisions.
- Control of cell division axes.
- Demarcation of fields of cells, as in the formation of compartments.
Are leaf shape and leaf vasculature developmentally coupled?
Morphogenesis of leaf shape and formation of the major elements of leaf vasculature are temporally coordinated during leaf development. Current analyses of mutant phenotypes provide strong support for the role of auxin signaling in vascular pattern formation and indicate that leaf shape and vasculature are developmentally coupled.
What is the second pattern element of the leaf’s vascular system?
The second pattern element of the leaf’s vascular system is the spatial arrangement of the two vascular tissues, xylem (the conduit for water and dissolved solutes) and phloem (the conduit for photosynthetic products), within each vein (i.e. the transectional pattern).
How are leaf veins arranged in a leaf?
First, leaf veins form a two dimensional array in the plane of the flattened leaf blade (the longitudinal pattern). In dicots, leaf venation forms a continuous, branching system with smaller veins diverging from larger ones and the smallest veins forming a closed reticulum ( Fig. 1 a).
Does auxin signaling affect leaf shape and vascular patterning?
Vascular patterning and leaf shape Morphogenesis of leaf shape and formation of the major elements of leaf vasculature are temporally coordinated during leaf development. Current analyses of mutant phenotypes provide strong support for the role of auxin signaling in vascular pattern formation and indicate that leaf shape and vasculat …