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Wheat Information
Service
Number 71: 27-28 (1990)
Chromosomal
location of gene for auricle development in common wheat
Li Waniong, Li Zhensheng and Huang Shousong
Northwestern. institute of Botany, Yanagting, Shaanxi, China
Like most Graminaceae. species, common wheat (Triticum
aestivum L.) has the leaf made up of blade, sheath, ligule and
auricle. As accessories of leaf, ligule and auricle are of botanical
significance. McIntosh and Baker (1968) located the genes controllong
ligule development on chromosomes 2B and 2D, but little is known
about the gene for auricle.
In using Chinese Spring (CS) ditelocentries to map alien segments, we
found that only ditelo-2DS was without auricle (Fig.1A).
Cytological identification confirmed its ditelocentric nature,2n = 40
+ 2t (Fig.1B).
What caused diteto-2DS auricleless, deletion of 2DL arm or point
mutation? For this purpose, a monosomic analysis was made. Monosomic
2D was pollinated with ditelo-2DS and 25 F1 hybrids were
produced. Seventeen auricleless offspring were monotelosomic, 20"+ t'
(Fig.
1C); the
remaining 8 auriclate plants were monotelodisomic, 20"+ t1"
(Fig.
1D). Obviously,
the gene responsible for auricle development is on chromosome 2D of
CS.
In order to determine the position of this gene on chromosome 2D,
F2 populations were surveyed for auricle. One hundred and
seventy plants grew from 270 seeds of selfed monotelodisomic
F1 hybrids with the emergence rate of 62.9%, 4 of which
were deficient of auricles and with chromosome number of 40 + 2t; in
contrast, 66 plants grew from 210 seeds of monotelosomic
F1 hybrids with the emergence rate of 31.4%, and all of
them were auricleless. Thus, two conclusions can be drown. First, the
gene controlling auricle is on the long arm of CS chromosome 2D.
Second, chromosome 2D of CS is of much importance to seedling
emergence in field conditions because monotelosomic F2 had
the emergence rate just half as high as monotelodisomic F2
had.
The present paper is the first report of cytogenetic study on auricle
in common wheat. According to McIntosh (1988), it is suggested that
this gene be named as Aur, its recessive allete as aur.
As a genetic marker, the possible use of aur in screening
nullisomic 2D and other related research could be expected.
References
McIntosh RA (1988) A catalogue of gene symbols for wheat. Proc
7th Int Wheat Genet Symp (Cambridge): 1225-1323.
McIntosh RA and Baker EP (1968) A linkage map for chromosome 2D. Proc
3rd Int Wheat Genet Symp (Aust Acad Sci, Canberra): 305-309.
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