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GrainGenes Gene Class Report: Glaucousness

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Gene Class
Glaucousness
Reference
ReferenceHen-Avivi S et al. (2016) A Metabolic Gene Cluster in the Wheat W1 and the Barley Cer-cqu Loci Determines B-Diketone Biosynthesis and Glaucousness. The Plant Cell 28:1440-1460.
[ Show all 8 ]
Abbreviation
W
See Also
Spike glaucousness
Character affected
Stem surface waxiness
Leaf color/glaucousness
Gene
W1 (Triticum)
[ Show all 9 ]
Allele
W1 (Triticum)
[ Show all 8 ]
Locus
W1
W2
Iw2
W2^I^
W2^I^-2D
Comment
[ Hide all but 1 of 8 ]
Glaucousness is the visual expression of waxiness and is the preferred term. Plants may be either 'waxy, glaucous' (the normal situation), 'waxy, non-glaucous' (e.g., Mentana), or 'low-wax, non-glaucous' (e.g., AUS 2598). The expression of glaucousness depends on the arrangement of wax deposits rather than the amount of wax (Johnson et al., 1983).
This phenotype was originally thought to be controlled by a series of wax-producing genes and an independent series of inhibitors (e.g., Matsumura, 1951; Tsunewaki, 1966), but later work (Stuckey and Driscoll, 1995) indicated that the wax-producing genes and the inhibitors are allelic. Hence, recessive alleles and dominant alleles may result in non-glaucousness.
Glaucousness refers to the whitish, wax-like deposits that occur on the stem and leaf-sheath surfaces of many graminaceous species. The expression of glaucousness depends on the arrangement of wax deposits rather than the amount of wax (Johnson et al., 1983). Non-glaucous variants also occur and genetic studies indicate that non-glaucousness can be either recessive or dominant. Recessive forms of non-glaucousness are apparently mutants of the genes that produce the wax-like deposits. Dominant non-glaucous phenotypes (as assessed visually) appear to be due to mutations that affect the molecular structure, and reflectance, of the wax-like substances (Tsunewaki and Ebana, 1999).
The genes involved in wax production and the 'inhibitors' are duplicated in chromosomes 2B and 2D. There appear to be independant genes for wax production and 'inhibitors' (Matsumura, 1951; Tsunewaki, 1966; Tsunewaki and Ebana, 1999).
In earlier issues of the gene catalogue the two kinds of genes were treated as multiple alleles (Stuckey and Driscoll, 1995).
All forms of wild and cultivated einkorn are non-glaucous (Tsunewaki and Ebana, 1999).
Orthologous loci occur in barley chromosome 2HS (gs1, gs6, gs8) (Graner et al., 1991) rye chromosome 7RL (wa1) (Korzun et al., 1997) and maize (gl2) (Coe and Neuffer, 1993).
The W loci are complexes of closely linked genes involved in beta-diketone synthesis. Glaucous synthetics LDN/KU-2104 and LDN/KU-2105 are presumed to have genotype W1W1W4W4 (Hen-Avivi et al., 2016).
Data Curator
Cooper, LaurelJune-2021

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