Everything about Dehiscence Botany totally explained
Dehiscence is the spontaneous opening at maturity of a plant structure, such as a
fruit,
anther, or
sporangium, to release its contents.
Anther dehiscence
This is the final function of the anther that causes the release of pollen grains. The anther wall breaks at a specific site that runs the length of the anther. This site is observed as an indentation between the
locules of each
theca.
The
stomium, and
septum are two specialised cell types present at this site. The degeneration of the stomium and septum cells is part of a developmentally timed cell-death program. Initially the septum degenerates thereby establishing the stomium as the future site of anther wall breakage and pollen release. Expansion of the
endothecial layer and lignification of the endothecial cell walls are required for dehiscence.
The process of anther dehiscence is coordinated precisely with pollen differentiation, floral development, and flower opening.
Fruit dehiscence
Typically a fruit develops from a
gynoecium composed of fused
carpels, which, upon fertilization, grow to become a
silique that contains the developing
seeds. After seed maturation, dehiscence takes place, and valves detach from the central
septum freeing the seeds. This is also known as
shattering and can be important as a
seed dispersal mechanism.
This process is similar to anther dehiscence and the region that breaks (dehiscence zone) runs the entire length of the fruit between the
valves and the
replum (external septum).
At maturity, the dehiscence zone is effectively a non-lignified layer between a region of lignified cells in the valve and the replum. Shattering occurs due to the combination of cell wall loosening in the dehiscence zone and the tensions established by the differential mechanical properties of the drying cells in the silique.
Association with crop breeding
Manipulation of dehiscence can improve crop yield since a
trait that causes seed dispersal is a disadvantage for farmers whose goal is to collect the seed. Many of the agronomically important plants have been bred for reduced shattering.
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