ITEMS FROM THE UNITED KINGDOM
JOHN INNES CENTRE
Norwich Research Park, Colney, Norwich NR4 7UH, United Kingdom.
Homoeologous gene silencing in hexaploid wheat.
[p. 161]
R. Koebner and G. Xia (Shandong University, PR China).
Many cDNA loci are triplicated in the wheat genome. However,
the presence of three homoeologous genomic sequences (one/genome) does not necessarily imply
that three independent mRNAs either are transcribed or successfully
translated. We have been using single-strand confirmation polymorphism
to distinguish the homoeologues of gDNA and cDNA (via RT-PCR)
sequences from mapped, single-copy cDNA sequences and have been
able to demonstrate that silencing of one of the three copies
occurs at a significant frequency (Figure 1). We aim to extend
this approach to explore both the extent of, and the existence
of any genomic patterning of homoeologous silencing in the hexaploid
and tetraploid wheat genomes.
Facultative pathogens of cereals. [p.
161]
P. Nicholson, E. Chandler, N. Chapman, R. Draeger, D. Simpson,
A. Steed, M. Thomsett, and A. Wilson.
We are continuing our studies of FHB and eyespot with emphasis
on the former (not reflected in the publication list below).
Resistance in wheat to FHB is being characterized in a number
of sources (not Sumai 3) using a trait-dissection approach. Visual
disease, yield loss, fungal biomass, and DON mycotoxin accumulation
are being determined and data used in QTL studies to identify
loci associated with each trait.
In addition, we are developing new diagnostic assays to improve
our ability to detect the major Fusarium species involved
in FHB in the U.K. and elsewhere. This work includes study of
variation within F. graminearum, particularly with respect
to lineage and chemotype. We have developed PCR assays that allow
chemotypes of isolates to be determined without the need for costly
mycotoxin analysis.
Work on eyespot is concentrating upon the identification of
DNA markers to Pch1 and Pch2. A cDNA-AFLP approach
is being used to identify markers linked to these resistances
and provide insight into potential mechanisms underlying the resistance.
Discovering genes for protein quantity and grain hardness
by marker-mediated genetic analysis in U.K. winter wheat germ
plasm. [p. 161-162]
R. Bradburne, A. Turner, L. Fish, and J. Snape.
In a project funded by the U.K. Home-Grown Cereals Authority
(HGCA), we have been identifying and analyzing major genes and
QTL-controlling attributes of end-use grain quality, in particular
grain texture, protein content, and grain size and shape, using
molecular marker-mediated methods of genetic analysis. Three
populations were studied: a series of RSLs containing a chromosome
5A recombinant between Avalon (hard, high protein) and Hobbit
Sib (soft, low protein) in a Hobbit Sib background, an analogous
series of RSLs recombinant at chromosome 5D, and a set of 'Avalon/Hobbit
Sib' RILs.
In the Hobbit Sib (Avalon 5D), markers significantly associated
with grain hardness were found on the short arm, indicating segregation
at the major hardness locus Ha. Additionally, this locus was
found also to have a significant effect on grain-protein content,
with hard lines having higher intrinsic protein, independent of
the grain-texture effect. It is not clear if this is a pleiotropic
effect of the Ha locus, but we think it is probably a linked locus.
Interval mapping for grain protein content also revealed a significant
QTL on the long arm of this chromosome, with Avalon contributing
the increasing effect, somewhere near to the location of the vernalization
gene Vrn-D1. Results from the Hobbit Sib (Avalon 5A) RSL
population indicated that although loci influencing grain-protein
concentration and grain hardness were consistent between both
years of the study, their effect was not strong enough to give
a statistical significance. However, the putative loci on 5A
and 5D appear homoeologous.
Results from the 'Avalon/Hobbit Sib' RILs by interval mapping
indicated statistically significant QTL for grain-protein content
and grain hardness over and above the 5A and 5D effects previously
detected using RSLs. QTL on chromosomes 2B and 6B were consistent
over 2 years of field trials, with Avalon contributing the increasing
effect in both cases. Single-year QTL also were significant on
chromosomes 6A (2001 only) and 7A (2002 only), both with Hobbit
Sib contributing the increasing effect. QTL mapping by multiple-marker
regression indicated significant, year-by-year consistent QTL
for hardness on chromosomes 1B (Avalon contributing the increasing
effect) and also 5BS/7BS (Hobbit Sib contributing the increasing
effect).
Publications. [p. 162-163]
- Börner A and Worland AJ. 2002. Does the Chinese dwarf
wheat variety 'XN0004' carry Rht21? Cereal Res Commun
30:1-2.
- Bourdon V, Ladbrooke Z, Wickham A, Lonsdale D, and Harwood
W. 2002. Homozygous transgenic wheat plants with increased
luciferase activity do not maintain their high level of expression
in the next generation. Plant Sci 163:297-305.
- Brading PA, Verstappen ECP, Kema GHJ, and Brown JKM. 2002.
A gene-for-gene relationship between wheat and Mycosphaerella
graminicola, the Septoria tritici blotch pathogen.
Phytopathology 92:439-445.
- Brown JKM. 2002. Comparative genetics of avirulence and
fungicide resistance in the powdery mildew fungi. In:
The Powdery mildews: a comprehensive treatise (Bélanger
RR, Bushnell WR, Dik AJ, and Carver TLW eds). APS Press, St.
Paul, MN, USA. Pp. 56-65.
- Brown JKM. 2002. Yield penalties of disease resistance
in crops. Curr Opinion Plant Biol 5:339-344.
Calonnec A, Johnson R, and Vallavieille-Pope C. 2002. Genetic
analyses of resistance of the wheat differential cultivars Carstens
V and Spaldings Prolific to two races of Puccinia striiformis.
Plant Path 51:777-786.
- Carter JP, Rezanoor HN, Desjardins AE, Plattner RD, and Nicholson
P. 2002. Variation in pathogenicity associated with genetic
diversity of Fusarium graminearum. Eur J Plant Path
108:573-583.
- Clua AA, Castro AM, Gimenez DO, Tacaliti MS, and Worland
AJ. 2002. Chromosomal effects in the endogenous content of
non-structural carbohydrates and proteins measured in wheat substitution
lines. Plant Breed 121:141-145.
- Covarelli L and Nicholson P. 2002. Identificazione dei
patogeni responsibili del mal del piede del frumento mediante
PCR. ATTI Giornate Fitopatolgiche 2:449-454 (in Italian).
- Flintham JE, Adlam R, Bassoi M, Holdsworth M, and Gale MD.
2002. Mapping genes for resistance to sprouting damage in wheat.
Euphytica 126:39-45.
- Gale MD, Flintham JE, and Devos KM. 2003. Cereal comparative
genetics and preharvest sprouting. Euphytica 126:21-25.
- Hernandez P, Laurie D, Martin A, and Snape JW. 2002. Utility
of barley and wheat simple sequence repeat (SSR) markers for
genetic anaylsis of Hordeum chilense and tritordeum. Theor Appl
Genet 104:735-739.
- Hovmøller MS, Justesen AF, and Brown JKM. 2002.
Clonality and long-distance migration of Puccinia striiformis
f.sp. tritici in north-west Europe. Plant Path 51:24-32.
- Justesen AF, Ridout CJ, and Hovmøller MS. 2002.
The recent history of Puccinia striiformis f.sp. tritici
in Denmark as revealed by disease incidence and AFLP markers.
Plant Path 51:13-23.
- Ke X-Y, McCormac AC, Harvey A, Lonsdale D, Chen D-F, and
Elliot MC. 2002. Manipulation of discriminatory T-DNA delivery
by Agrobacterium into cells of immature embryos of barley and
wheat. Euphytica 126:333-343.
- Koebner R and Summers R. 2002. The impact of molecular
markers on the wheat breeding paradigm. Cell Mol Biol Lett
7:695-702.
- Laurie DA and Devos KM. 2002. Trends in comparative genetics
and their potential impacts on wheat and barley research. Plant
Mol Biol 48:729-740.
- McKibbin RS, Wilkinson MD, Bailey PC, Flintham JE, Andrew
LM, Lazzeri PA, Gale MD, Lenton JR, and Holdsworth MJ. 2002.
Transcripts of Vp-1 homeologues are mis-spliced in modern
wheat and ancestral species. Proc Natl Acad Sci USA 99:10203-10208.
- Muranty H, Jahier J, Tanguy A-M, Worland AJ, and Law C.
2002. Inheritance of resistance of wheat to eyespot at the adult
stage. Plant Breed 121:536-538.
- Nicholson P, Turner AS, Edwards SG, Bateman GL, Morgan LW,
Parry DW, Marshall J, and Nuttall M. 2002. Development of stem-base
pathogens on different cultivars of winter wheat determined by
quantitative PCR. Eur J Plant Path 108:163-177.
- Robinson HL, Ridout CJ, Sierotzki H, Gisi U, and Brown JKM.
2002. Isogamous, hermaphroditic inheritance of mitochondrion-encoded
resistance to Qo inhibitor fungicides in Blumeria graminis
f. sp. tritici. Fungal Genet Biol 36:98-106.
- Smith PH, Koebner RMD, and Boyd LA. 2002. The development
of STS marker linked to yellow rust resistance derived from the
wheat cultivar Moro. Theor Appl Genet 104:1278-1282.
- Turner AS, Nicholson P, Edwards SG, Bateman GL, Morgan W,
Todd AD, Parry DW, Marshall J, and Nuttall M. 2003. Relationship
between brown foot rot and DNA of Microdochium nivale,
determined by quantitative PCR, in stem bases of winter wheat.
Plant Path 51:464-471.
- Wardrop J, Snape JW, Powell W, and Machray GC. 2002. Constructing
plant radiation hybrid panels. Plant J 31:223-228.
- Wilkinson MD, McKibbin RS, Bailey PC, Flintham JE, Gale MD,
Lenton JR, and Holdsworth MJ. 2002. Use of comparative molecular
genetics to study preharvest sprouting in wheat. Euphytica
126:27-33.