What is callose deposition?
Callose is a cell wall component that is dynamically deposited and degraded during pollen development. It is transiently deposited at sites of wounding, plasmodesmata, and pollen cell walls (Chen and Kim, 2009).
Why is callose deposition important in Microsporogenesis?
Callose walls prevent microsporocytes fusion and cohesion, and the timely degradation of the walls facilitates the release of microspores from tetrads during late meiosis. Thus, callose plays an essential role in meiosis. Callose deposition is also associated with female reproductive development.
What is callose phloem?
It has been known for more than a century that sieve plates in the phloem in plants contain callose, a β-1,3-glucan. In wild-type Arabidopsis plants, callose is present as a constituent polysaccharide in the phloem of the stem, and its accumulation can also be induced by wounding.
Which is covered by callose wall?
Sporogenous cells divide to form pollen grain or microspore mother cells. They are diploid and connected by plasmodesmata. The microspore, mother cells consists of a callose wall inner to the cell wall.
Where does the callose deposition is found?
Callose is frequently found to deposit at PD, where it is generally believed to control the movement of molecules through plasmodesmata as a developmental regulator of symplasmic continuity. Callose can also deposit at PD in response to abiotic and/or biotic stresses.
What is callose formation?
Callose is a plant polysaccharide. Its production is due to the glucan synthase-like gene (GLS) in various places within a plant. It is produced to act as a temporary cell wall in response to stimuli such as stress or damage.
What is the function of callose?
Callose is involved at multiple stages of pollen development as a structural component. It is also deposited at cell plates during cytokinesis. In addition, callose can be deposited at plasmodesmata (PD) to regulate the cell-to-cell movement of molecules by controlling the size exclusion limit (SEL) of PD.
What is the importance of the callose that forms inside the pollen tube?
Pollen tube walls of flowering plants contain callose that resides in the tube wall and forms the plugs that separate the growing tip from the evacuated tail. The callose plug keeps the pollen cytosol within a reasonably small volume and therefore has been thought to play an important role for fertilization.
What is callose deposition and its significance?
Callose is frequently found to deposit at PD, where it is generally believed to control the movement of molecules through plasmodesmata as a developmental regulator of symplasmic continuity. Callose can also deposit at PD in response to abiotic and/or biotic stresses. Here we will focus on its developmental roles.
Which enzyme is responsible to dissolve the callose?
callase enzyme
Tapetum provides nourishment to developing microspores. It also secretes callase enzyme which dissolves callose substances by which four pollens of a pollen tetrad are united, hence separating microspores or pollens of a tetrad.
What is Intine made up of?
cellulose
The intine, or inner layer, consists primarily of cellulose and pectins. The exine, or outer layer, is composed of a highly decay-resistant chemical called sporopollenin.
How is callose formed?
Formation and function Callose is produced in response to wounding, infection by pathogens, aluminium, and abscisic acid. When there is wounding in the plant tissue, it is fixed by the deposition of callose at the plasmodesmata and cell wall; this process happens within minutes after damage.
When does the callose wall degenerate in the anther?
The callose wall degenerates at the late tetrad stage, releasing microspores, which are surrounded by the developing exine ( Dong et al., 2005; Ariizumi and Toriyama, 2011 ). Abnormal callose accumulation and degradation during anther development may cause abortive male gametophyte development ( Ariizumi and Toriyama, 2011; Shi et al., 2015 ).
Where is callose deposited in a pollen cell?
In pollen development, callose, a polysaccharide of β-1,3-glucan with β-1,6-branches ( Chen and Kim, 2009 ), is biosynthesized and deposited outside the plasma membrane (PM) during meiosis, forming a temporary layer that separates pollen mother cells (PMCs) within an anther locule.
How does callose play a role in plant development?
Callose plays important roles during a variety of processes in plant development and/or in response to multiple biotic and abiotic stresses. It is now generally believed that callose is produced by callose synthases and that it is degraded by beta-1,3-glucanases.
How does rice gsl5 and UGP1 affect callose deposition?
UGP1 affects callose deposition during PMC meiosis and microspore development ( Chen et al., 2007 ). Rice GSL5 is critical for callose biosynthesis during microsporogenesis, as GSL5 knockout or knockdown causes defective callose deposition on meiocyte cell walls and tetrad cell plates, resulting in male sterility ( Shi et al., 2015 ).