Institut National de la Recherche Agronomique (INRA)
Station d'Amelioration
des Plantes, BP 29, 35650 Le Rheu, France.
G. Doussinault, J. Jahier, M. Trottet, D. Barloy, P. Robe, F. Dedryver, and B. Rolland.
New cultivars and germplasm releases.
'Regain' bread wheat, developed
by Institut National de la Recherche Agronomique, was released
in 1994. The parentage of Regain is `R3-7/Bounty//Adam/3/R3-7/Bounty//Darius'.
R3-7 was derived from `VPM/Moisson//US(60)43/Prieur'.
The cross was made in 1982 at the Le Rheu Plant breeding Station.
Plants were selected in a pedigree scheme for short straw and
leaf disease resistance (stripe and leaf rusts, powdery mildew,
and leaf blotch). Resistance to eyespot was assessed in the F5
for seedling resistance and in the F6 for adult plant
resistance. Yield and baking quality were tested from the F6
generation.
Regain has a winter growth habit, is
early heading, and is short strawed with an awnless spike. It
has a good level of resistance to lodging. Regain has resistance
to eyespot conferred by the gene Pch1, derived from Aegilops
ventricosa via VPM and R3-7. It has a good level
of resistance to leaf rust, stripe rust, and powdery mildew and
is moderately resistant to Septoria nodorum blotch.
It is moderately susceptible to Fusarium head blight.
Regain is high-yielding with good stability over the years and
locations, mainly because of its good level of resistance to diseases
and to lodging. It has a very good quality for making French
bread. This variety is adapted to southern France. Regain is
a registered variety and is maintained by Agri Obtentions, domaine
de la Miniere, BP46, 78042 Guyancourt, France, which produces
commercial seeds. Small samples of seed for scientific purposes
can be obtained from G. Doussinault.
The winter wheat line RE714, derived
from an interspecific cross between Ae. squarrosa
(33) and Triticum dicoccum (119), and with a Roazon
sib-line (VM4) and Beauchamp in its pedigree has a good level
of resistance to several diseases: yellow and brown rust, powdery
mildew, and eyespot. An analysis has been undertaken to identify
the powdery mildew resistance gene(s) present in this line that
are effective from the seedling stage on. The comparison of the
reaction of RE714 and one of differentials to a wide collection
of mildew isolates indicated that only Pm4a, Pm4b,
and/or mlar genes could be present and that a new resistance
factor, different from any of the described resistance genes,
was present in this line. The analysis of F2 segregating
populations demonstrated that RE714 carries the Pm4b gene
and a new recessive resistance gene, with the proposed denomination,
mlre. The chromosomal location of this gene is being investigated
by cytogenetical analysis. Aegilops squarrosa was
resistant to most of the isolates. Triticum dicoccum
was attacked specifically by RE714-virulent isolates and,
therefore, is assumed to be the donor of mlre. The VM4
parent was proven to be the Pm4b donor. When these resistance
genes are overcome, RE714 expresses an adult plant resistance.
The genetic determination of this resistance is being analysed.
'AS6', an amphiploid between Ae. squarrosa (33) and T. dicoccum (8) has a high level of resistance to S. nodorum and S. tritici. This resistance is mainly from Ae. squarrosa. The analysis of the substitution lines of the D genome of AS6 into T. aestivum cv. Cappelle, for the reaction of adult plants towards S. tritici, has been made in a glasshouse and in the field in 1993 and 1994. There is a great range of variation for resistance between substitution
lines. No substitution line is as resistant
as AS6, but the level of resistance of the substitution line for
chromosome 2D is high and close to that of AS6. Substitution
line 7D is very susceptible (more than Cappelle). The reactions
of the other lines range from moderately resistant to moderately
susceptible. These results suggest that chromosome 2D might carry
major factors of resistance, but that the resistance of Ae.
squarrosa and AS6 is the result of interactions between
several chromosomes.
Hybrids between T. aestivum
cv. Chinese Spring and Agropyron cristatum (2n =
4X = PPPP) with a high level of homoeologous meiotic pairing between
the wheat chromosomes were backcrossed three times to wheat.
Derived lines were identified in the BC3 progenies
by RFLP analysis using a set of assigned wheat DNA probes. So
far, four stable disomic addition lines (1P, 3P, 5P, and 6P);
two monosomic addition lines (2P and 4P); and four ditelosomic
addition lines (2PL, 5PL, 6PL, and 6PS) have been produced. The
telocentric chromosomes are being introduced into a ph
background in order to evaluate the possibilities of transferring
to wheat A. cristatum genetic information.
Recent publications.
Rivoal R, Jahier J, and Hulle M. 1993.
Partial resistance to Heterodera avenae in wheat
lines with the 6Mv chromosome from Aegilops ventricosa.
J Nemat 25:265-269.
Chen Q, Jahier J, and Cauderon Y. 1993.
The B chromosome system of Inner Mongolian Agropyron Gaertn.
Cytogenetical evidence for B-A
pairing at metaphase I. Hereditas 119:53-58.
Chen Q, Jahier J, and Cauderon Y. 1993.
The B chromosome system of Inner Mongolian Agropyron Gaertner.
1. Distribution, morphology and cytological behaviour. Caryologia
46:245-260.
Chen Q, Jahier J, and Cauderon Y. 1993.
The B chromosome system of Inner Mongolian Agropyron Gaertner.
2. Effects of Bs on homologous and homoeologous meiotic
chromosome pairing. Caryologia 46:293-299.
Chen Q, Lu YL, Jahier J, and Bernard
M. 1994. Identification of wheat-Agropyron
cristatum monosomic addition lines by RFLP analysis using
a set of assigned wheat DNA probes. Theor Appl Genet 89:70-75.
Institute of Plant Genetics and Crop Plant Research (IPK)
Correnstrasse
3, 06466, Gatersleben, Germany.
Alternative dwarfing genes and their pleiotropic effects.
Two sets of near isogenic lines (four to six backcrosses) carrying the alternative dwarfing genes Rht(Saitama) and Rht(Krasnodari), both GA insensitive, and the GA-sensitive allele Rht12 in the genetical backgrounds of the wheat varieties 'Bezostaya' and 'Cappelle-Desprez', were grown together with their tall controls in a randomized design. The Bezostaya lines were grown at two places in central Germany, whereas the Cappelle-Desprez set was grown in northern
Germany. The effects on plant height,
yield, and yield components were studied. For plant height in
both genetical backgrounds, the same ranking was observed: Rht(Saitama)
< Rht(Krasnodari) < Rht12. However, absolute
values did vary between the two genetical backgrounds. Analyzing
the pleiotropic effects on grain yield and yield components, it
was shown that the most consistent effects of the alternative
Rht genes were not only on grain weight, but also on the
number of grains per ear. The isogenic lines usually had a significantly
reduced grain weight compared to their rht (tall) controls,
but produced more grains per spike. Grain yield was not influenced
by the GA-insensitive alleles Rht(Saitama) and Rht(Krasnodari).
Therefore, both alleles localized at the Rht1 locus on
chromosome 4B could be used successfully by the breeders to reduce
the final plant height without yield loss under the growing conditions
of Germany. However, for Rht12,, a significant reduction
in ear yield and plot yield was found in the trials grown in northern
Germany.
Chromosomal location of genes for promotion or suppression of mildew resistance.
The monosomic series of the wheat varieties
Cappelle-Desprez, Poros, and Hobbit sib were grown together
with one set of intervarietal substitution lines `Cappelle-Desprez/Poros'
as a joint experiment at one site in Germany and one in England
(single rows with three replicates). The field trails were infected
naturally with powdery mildew. The plants were scored at weekly
intervals after the first infection was observed. The levels
of infection on the monosomic and substitution lines showed marked
positive and negative deviations from the euploid control, indicating
the presence of genetical factors for both promotion of resistance
and susceptibility or suppression of resistance on particular
wheat chromosomes. For the Cappelle-Desprez monosomic series,
it was found that the mean infections of monosomics 1B and 2A
were significantly higher than that of the euploid control both
in Germany and England. Thus, these chromosomes should carry
genes for resistance to mildew. In addition, five monosomics
(2D, 3D, 4A, 4B, and 5A) with increased resistance and carrying
genes promoting susceptibility or suppressing the effect of resistance
genes on other chromosomes, were found in the German trial only.
The screening of the Poros monosomics showed a reduced dosage
of nine chromosomes (1B, 2D-7B, 3D, 4B, 5A, 5D, 6A, and 6D)
significantly increased levels of resistance in Germany. The
same effect was found for three chromosomes (1B, 2A, and 4D) of
Hobbit sib, whereas the reduced dosage of chromosome 3A of Hobbit
sib significantly increased the level of susceptibility. In the
investigations in England, no significant differences were found,
in either the Poros or the Hobbit sib lines owing to severe infections
of yellow rust. Analyzing the intervarietal substitution lines
showed that the Cappelle-Desprez/Poros substitution lines
1A, 2D-7B,
and 3D (Germany) and 2B, 2D-7B,
3D, and 7A (England) were more susceptible than the recipient
variety Cappelle-Desprez. No Poros chromosomes significantly
improved the resistance to mildew compared to Cappelle-Desprez.
By comparing the results obtained in both countries, in only
four cases were corresponding significant effects of particular
chromosomes detected: for the Cappelle-Desprez monosomics
1B and 2A and the Cappelle-Desprez/Poros 2D-7B
and 3D substitutions.
Genetics of GA insensitivity of two Ethiopian wheats.
Out of 120 Ethiopian wheat accessions
from the Gatersleben gene bank, two tetraploids belonging to the
subspecies Triticum aethiopicum Jakubz. were found
to be GA3 insensitive. The two accessions (W 6824D,
W 6807C) were crossed both with the GA-sensitive tetraploid wheat
variety 'Castelporziano' (rht) and the GA- insensitive
tetraploid wheat 'Cocorit 71' (Rht1). About 120 F2
seedlings per combination were scored for their GA3
response at the seedling stage. There was clear evidence that
the GA insensitivity of both Ethiopian wheats is determined by
a single semidominant gene, allelic to Rht1, on chromosome
4B.
Homoeologous relationships of GA3-sensitive dwarfing genes in wheat and rye.
Several GA-sensitive dwarfing genes are described in wheat. One of them, Rht12, is known to be located on the long arm of chromosome 5A. By studying the allelic variation at the FONT SIZE=2 FACE="WP MultinationalA Roman"8-Amy-A1 isozyme locus, a recombination frequency of 0.025 FONT SIZE=2 FACE="WP MathA"" 0.054 between Rht12 and FONT SIZE=2 FACE="WP MultinationalA Roman"8-Amy-A1 was calculated. This tight linkage indicates that Rht12 is
located on the segment of 5AL that was
translocated ancestrally from 4AL. In comparison to this, genetical
studies were carried out in rye analyzing the dominant GA-sensitive
dwarfing gene, Dw1 (chromosome 5R). Again, a linkage to
the isozyme marker, FONT SIZE=2 FACE="WP MultinationalA Roman"8-Amy-R1,
was found (10.9 cM). This supports the theory that the two genes
are members of a homoeologous series in which a linked marker
found in one species could be used as a tag in the other species.
The wheat varieties 'Chinese Spring',
'Marquis', and 'Thatcher' and five intervarietal Chinese Spring
substitution lines for chromosome 2B (Marquis-Thatcher,
Cheyenne); 2D (Cappelle-Desprez, Timstein); and 4A (Timstein),
differing from the recipient variety in alleles for hybrid dwarfing
genes (D) and/or the photoperiodic response genes (Ppd),
were analyzed for tissue culture response (TCR). Results demonstrated
that only chromosome 2B has a major effect on TCR. Allelic variation
at the hybrid dwarfing loci seems to have no effect on tissue
culture performance, even in the combination D1D2D3, which
gives the grass-dwarf phenotype. Also, the allelic constitution
at the Ppd loci gives no indication for a direct major
effect of those alleles. However, genetical factors for TCR that
may be closely linked to the Ppd loci seem to exist on
the homoeologous group 2 chromosomes.
The relation between green-spot initiation
and plant regeneration of wheat callus was studied using seven
genotypes. The distribution of green-spot initiation per week
over a 4-week period was similar for all genotypes, whereas differences
were significant for the shoot regeneration genotype. Shoot regeneration
of 75.7 % and 35.7 % was observed from calli differentiated in
the first and in the last 2 weeks on the maintenance medium, respectively.
These results suggest that late differentiated calli were mostly
nonembryogenic. For all genotypes studied, the correlation between
green spots (maintenance medium) and plant regeneration (regeneration
medium) was between r = 0.80 and r = 0.97. Thus, green-spot initiation
could be used in selecting embryogenic cultures. Moreover, the
efficiency could be maintained and the costs for culturing reduced
by selecting only calli that initiated green spots within the
first 2 weeks of culturing.
The polymerase chain reaction (PCR)
has been used both to identify the polymorphism of sequences of
the clustered FONT SIZE=2 FACE="WP Greek Century""-Amy
gene family of wheat, rye, or barley and to locate them on chromosomes
by using nulli-tetrasomic lines of wheat and wheat-rye
addition lines. The analysis of amplification products with specific
genes for FONT SIZE=2 FACE="WP Greek Century""-Amy
has determined polymorphism of the amplified products of wheat,
rye, and barley. For all three species of cereals, the presence
of a common fragment of approximately 150 bp was obvious and,
thus, suggests that this sequence is very similar in the three
cereals. However, at least four polymorphic fragments that are
different between rye, wheat, and barley were detected. The use
of nulli-tetrasomic wheat lines permits the location of some
of the wheat fragments on chromosomes 7A and 7B.
Publications.
Sagi H, Boerner
A, Bartok T, and Sagi F. 1993. Genetic identification, agronomic
performance and technological quality of tissue culture-induced
dwarfs of the Mv4 winter wheat. Cereal Res Comm 21:309-315.
Boerner
A, Schumann E, and Worland AJ. 1994. Der Effekt von Genen fuer
Tageslaengenreaktion
auf morphologische und Ertragsmerkmale beim Weizen. Vortraege
Pflanzenzuecht
28:156-158.
Ben Amer IM and Boerner
A. 1994. Untersuchungen zur Gewebekultureignung beim Weizen
unter Verwendung von intra- und interspezifischen Substitutionslinien.
Vortraege
Pflanzenzuecht
28:38-40.
Boerner
A. and Worland AJ. 1994. Breeding for lodging resistance in
wheat and the utilisation of dwarfing genes. Proc Symp 'Future
Prospectives of Cereal Breeding in Europe' Cereal Section of Eucarpia,
Plantahof, Landquart, Schweiz, 4 bis 7 September 1994. Pp. 169-170.
Korzun V, Popendikite V, and Boerner
A. 1994. Use of polymerase chain reaction (PCR) for identification
of cereal genomes. Proc Symp 'Future Prospectives of Cereal Breeding
in Europe' Cereal Section of Eucarpia, Plantahof, Landquart, Schweiz,
4 bis 7 September 1994. Pp. 37-38.
Korzun V, Kartel N, Plaschke J, and
Boerner
A. 1994. Construction and screening of a rye DNA library for
RFLP mapping. Cereal Res Comm 22:151-157.
Worland AJ, Sayers EJ, Boerner
A. 1994. The genetics and breeding potential of Rht12,
a dominant dwarfing gene in wheat. Plant Breed 113:187-196.
Ben Amer IM, Worland AJ, and Boerner
A. 1995. Chromosomal location of genes affecting tissue culture
response (TCR) in wheat. Plant Breed (In press).
Plaschke J, Korzun V, Koebner RMD, and
Boerner
A. 1995. Mapping of the GA3-insensitive dwarfing
gene ct1 on chromosome 7R in rye. Plant Breed (In press).
Institut fuer Pflanzenpathologie und Pflanzenschutz der Universitaet
Gerog August University, Grisebachstr. 6,
D-37077 Goettingen,
Germany.
J. von Kietzell and K. Rudolph.
Studies on the epidemiology of Pseudomonas
syringae pv. atrofaciens using spontaneous mutants resistant to
rifampicin and streptomycin.
The incitant of basal glume rot of
cereals, Pseudomonas syringae pv. atrofaciens
(Psa), is a widespread epiphyte on wheat and barley and
occurs less frequently on rye, oats, and triticale (Von Kietzell
and Rudolph 1993, Ann Wheat Newslet 39:148-149). During a survey
in 1993, the pathogen was detected on a high percentage of symptomless
glumes and leaves of wheat and barley in three regions of northern Germany, where the bacterial concentration reached 107
cfu/symptomless barley glume (Von Kietzell and Rudolph 1994, Ann
Wheat Newslet 40:103-104).
In 1994, the epidemiology of Psa
was studied in field experiments. For this purpose, spontaneous
mutants resistant to streptomycin and rifampicin were selected.
Resistance to these two antibiotics proved to be stable and did
not affect pathogenicity.
Seeds of wheat, barley, rye, and oats
were vacuum infiltrated for 5 min with an inoculum concentration
of 108 cells/ml of an antibiotic resistant strain.
The inoculated seeds were dried at room temperature and sown
in spring 1994. After gemination, leaf samples were homogenized
and plated onto King B-Agar to which streptomycin and rifampicin
were added to identify the resistant bacteria. In these field
experiments, typical disease symptoms did not occur on the leaves
or heads. As a consequence, all bacterial isolates originated
from samples without symptoms.
The pathogen was found on the first true leaves of wheat, barley, rye, and oats. The following leaves were initially pathogen-free, but after a period of cold and humid weather, the bacteria were isolated from the third leaves. Successively, the bacteria reached the upper leaves and finally were found on the flag leaves. After a thunderstorm with
heavy rainfall, the bacteria were found
on the ears of rye where they persisted during the hot and dry,
ripening period. Later, the bacteria also were detected in or
on the seed. The bacteria could not be detected on the ears of
wheat and barley or on the panicles of oats. Earlier, rye was
found to be an inferior host for the epiphytic and pathogenic
growth of wild type strains of Psa when compared to wheat
and barley. Therefore, the intensive colonization of rye by the
bacterial pathogen was unexpected.
The percent of first leaves bearing
the bacteria increased from 20 % to over 80 % during the vegetation
period. Thirty-five percent of the flag leaves and 20 % of the
rye ears proved to bear the pathogen. Average bacterial concentration
ranged from 101 to 104 cells/leaf, and 105
cells/leaf were recorded in single cases.
These results indicated a vigorous
ability of Psa for epiphytic growth that was not well documented
in earlier studies. Presumably, the isolation of epiphytic Psa
strains from unspecific symptoms has frequently misled investigators
to erroneous diagnosis of the disease.