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n. Botany
A complex branched carbohydrate commonly associated with sieve areas of sieve elements.

[From Latin callōsus, callous; see callous.]


(Botany) a carbohydrate, a polymer of glucose, found in plants, esp in the sieve tubes


(ˈkæl oʊs)

1. having thickened or hardened spots, as a leaf.
[1860–65; < Latin callōsus]
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References in periodicals archive ?
These defense mechanisms include: strengthening of the cell wall through lignin, suberin and callose deposition as well as by the synthesis of phytoalexins which are toxic to bacteria and fungi by producing Pathogenesis-Related (PR) proteins like chitinases, b-1,3-glucanases, and thaumatin-like proteins (Bowles, 1990).
According to Kays (1991), the increase in respiratory rate in response to injury is related to the healing process, with the formation of lignin, suberin and in some cases callose.
A small pollinic tube elongation, along with a low boron concentration, is related to the callose synthesis, which induces the synthesis of phytoalexins (comprising phenols) in the stigma.
30 teeth per side in the proximal leaves, and 7-12 teeth per side in the distal leaves, teeth in two size classes, the short ones interspersed with the long ones, obtuse, apex acute to shortly acuminate and often ending in a callose tooth, adaxial surface dark green, glabrous, abaxial surface green suffused with purple, glabrous, venation brochidodromous, prominent on the abaxial surface, (7-)9-11(-14) pairs of secondary veins in the proximal leaves and 5-10 pairs in the distal leaves, irregularly interspaced, higher order venation conspicuous, reticulate, submarginal vein present but interrupted.
pollen which showed present abnormalities pollen tube as bifurcated monosphonic pollen tube, pollen tube with a wavy structure, pollen tube due to cytoplasm deposition and wall swelling, pollen tube with thickened walls, pollen tube with callose formation at its tips and Callose plugs formed in pollen tube cytoplasm, but this research did not mention percentage of each type.
Exine pattern determination was originally attributed to callose (e.
The first barrier against the entering of heavy metals, especially regarding root level, is the immobilization of heavy metals in the cell wall and by extracellular carbohydrates, such as mucilage and callose (FRITZ, 2007; KARTEL et al.
Jones D, Blancaflor E, Kochian L, Gilroy S (2006) Spatial coordination of aluminium uptake, production of reactive oxygen species, callose production and Wall rigidification in maize roots.
In a genetic screen we identified gain-of-function mutations in a locus that codes for a CALLOSE SYNTHASE isoform CALS3.
2B), male also with a pair of yellow callose spots close to posterior margin of sternite VIII.
Microtubule involvement in the deposition of radial fibrilla callose arrays in stomata of the fern Asplenium nidus L.