A Database for Triticeae and Avena
report: Chromosome 7H
ND 58105, USA
Hard-copy edition pages 149 - 151.
Mapping and marker development progressed in the
last year, both for barley and for two related Hordeum species. Researchers looked at single genes and QTLs for
disease resistance, morphological markers, and many agronomic traits.
Macaulay and colleagues at SCRI, 2001 selected a
‘genotyping set’ of 48 well characterized SSR markers for genetic studies in
barley. Seven of these markers are located on chromosome 7H. When tested
against a reference set of 24 barley genotypes, these SSRs on chromosome 7H had
polymorphism information content values ranging from 0.41 to 0.87, indicating
they should be useful in a large number of crosses. Research has continued on
combining the physical and molecular maps of barley. Serizawa et al., 2001 examined a series of 22
deletion and translocation stocks in the wheat-barley addition lines for
chromosome 7H. The stocks were used for deletion mapping of 17 AFLP and 28 STS
markers. The deletion stocks provided additional breakpoints that were not
recovered in the previous studies using translocation stocks. Marker orders
matched previous maps.
Agronomic trait QTLs were located in three reports.
Marquez-Cedillo et al., 2001 analyzed
QTL for agronomic traits in a doubled haploid population derived from
Harrington x Morex. They found QTLs on chromosome 7H for heading date and
height using the full population, and a QTL for kernel plumpness using a
2-rowed sub-population. QTLs in a Mediterranean population derived from Tadmor
x Er/Apm were located by Teulat et al.,
2001. Significant regions on chromosome 7H were identified for height and
heading date, both in single locations and in the overall analysis. QTLs for
yield and harvest index were identified that were important only in certain
environments. Choo et al., 2001
examined associations between the nud
hulless gene and agronomic traits in a population of doubled haploid lines from
Kunlun no.1 x CIMMYT no.6. Hulless lines generally had lower yield, seed weight,
plant density and emergence rate, were shorter and had higher test weights.
Disease resistance-related loci were mapped to
chromosome 7H in two studies. Scheurer et
al., 2001 analyzed QTLs for tolerance
to BYDV-PAV in two populations derived from the resistant cultivar Post. After
inoculating the lines with the virus, they found that one region on chromosome
7H was associated with an increase in kernel yield and another was associated
with earlier heading. A new leaf stripe resistance gene was mapped by Tacconi et al.,
2001. They mapped the Rgd2a gene from
the cultivar Thibaut to the telomeric region of 7HS and developed STS primers
linked RAPD and RFLP markers. The resistance gene is located in the same region
as genes for resistance to stem rust, powdery mildew and scald.
Other QTL mapping projects looked at additional
traits. Takahashi et al., 2001 mapped
QTLs for deep-seeding tolerance in the Steptoe x Morex and Harrington x TR306
One significant QTL was located on the short arm of chromosome 7H in the
Steptoe x Morex population. They also located QTLs for kernel weight and first
internode length on 7H in both populations. Bregitzer and Campbell, 2001 also
used the Steptoe x Morex mapping population to locate QTLs for green and albino
plant regeneration from barley callus cultures. They identified eight regions
associated with green plant regeneration, one from Steptoe which was located on
7H. They then used their mapping data to develop a model to predict
regeneration response, which explained approximately 62% of the variability for
An additional map was developed for the Oregon
Wolfe Barleys (Costa et al., 2001).
This involved a cross between the recessive and dominant morphological marker
stocks, which segregated for twelve morphological traits. The map they
developed for chromosome 7H includes four SSR, 13 RFLP, 1 RAPD and 143 AFLP
markers, and covers 191 cM. Two morphological traits, for naked caryopsis (nud) and for short awn (lks2), were included in this chromosome.
Two studies report the creation of linkage maps in
related Hordeum species and their
comparison to maps in barley and wheat. A map of H. chilense was
developed by Hernandez et al., 2001.
The map of 123 markers contained 26 RAPD and 1 RFLP marker on the chromosome
homoeologous to barley 7H. In general, marker order was consistent with that
found in barley and wheat. Salvo-Garrido et
al., (2001) developed an RFLP map of diploid H. bulbosum. Recombination in this species was lower than barley in
centromeric regions but similar or greater in more distal regions. The
chromosome 7H map contained 22 loci that showed good collinearity with the
barley and Triticeae consensus map order.
Bregitzer, P. and R.D. Campbell. 2001. Genetic
markers associated with green and albino plant regeneration from embryogenic
barley callus. Crop Sci. 41:173-179.
Choo, T.-M., K.M. Ho, and R.A. Martin. 2001. Genetic
analysis of a hulless x covered cross of barley using doubled-haploid lines.
Crop Sci. 41:1021-1026.
Costa, J.M., A. Corey, P.M. Hayes, C. Jobet, A.
Kleinhofs, A. Kopisch-Obusch, S.F. Kramer, D. Kudrna, M. Li, O. Riera-Lizarazu,
K. Sato, P. Szucs, T. Toojinda, M.I. Vales, and R.I. Wolfe. 2001. Molecular
mapping of the Oregon Wolfe Barleys: a phenotypically polymorphic
doubled-haploid population. Theor. Appl. Genet. 103:415-424.
Hernández, P., G. Dorado, P. Prieto, M.J. Giménez,
M.C. Ramírez, D.A. Laurie, J.W. Snape, and A. Martin. 2001. A core genetic
map of Hordeum chilense and
comparisons with maps of barley (Hordeum
vulgare) and wheat (Triticum aestivum).
Theor. Appl. Genet.102:1259-1264.
Macaulay, M., L. Ramsay, W. Powell, and R. Waugh.
2001. A representative, highly informative ‘genotyping set’ of barley SSRs.
Theor. Appl. Genet. 102:801-809.
Marquez-Cedillo, L.A., P.M. Hayes, A. Kleinhofs,
W.G. Legge, B.G. Rossnagel, K. Sato, S.E. Ullrich, D.M. Wesenberg, and the
North American Barley Genome Mapping Project. 2001. QTL analysis
of agronomic traits in barley based on the doubled haploid progeny of
North American varieties representing different germplasm groups. Theor. Appl.
Salvo-Garrido, H., D.A. Laurie, B. Jaffé, and J.W.
Snape. 2001. An RFLP map of diploid Hordeum
bulbosum L. and comparison with maps of barley (H. vulgare L.) and wheat (Triticum
aestivum L.). Theor. Appl. Genet. 103:869-880.
Scheurer, K.S., W. Friedt, W. Huth, R. Waugh, and
F. Ordon. 2001. QTL analysis of tolerance to a German strain of
BYDV-PAV in barley (Hordeum vulgare
L.). Theor. Appl. Genet. 103:1074-1083.
Serizawa, N., S. Nasuda, F. Shi, T.R. Endo, S.
Prodanovic, I. Schubert, and G. Künzel. 2001. Deletion-based physical mapping
of barley chromosome 7H. Theor. Appl. Genet. 103:827-834.
Tacconi, G., L. Cattivelli, N. Faccini, N.
Pecchioni, A.M. Stanca, and G. Valé. 2001. Identification and mapping of a
new leaf stripe resistance gene in barley (Hordeum
vulgare L.). Theor. Appl. Genet. 102:1286-1291.
Takahashi, H., K. Sato, and K. Takeda. 2001. Mapping genes
for deep-seeding tolerance in barley. Euphytica 122:37-43.
Teulat, B., O. Merah, I. Souyris, and D. This.
2001. QTLs for agronomic traits from a Mediterranean barley progeny grown in
several environments. Theor. Appl. Genet. 103:774-787.