Tan spot (Pyrenophora tritici-repentis) resistance was analyzed in a population of recombinant inbred lines of wheat derived from the cross of the synthetic bread wheat, W-7984 (resistant), and Opata 85 (susceptible). This population is also the subject of an extensive genome mapping effort by investigators of the International Triticeae Mapping Initiative (ITMI). Symptoms of tan spot are chlorosis and/or necrosis. This population was screened with conidia and toxin produced by isolates of three different pathotypes designated by their ability to cause chlorosis or necrosis on susceptible genotypes: (chl+ nec+), (chl+ nec-), and (chl- nec+). Segregation was observed for resistance to
(chl+ nec+) and (chl+ nec-)
isolates. The entire population exhibited resistance to the (chl-
nec+) isolate. This suggests that this population is segregating
for resistance to chlorosis only. Markers on the ITMI map explain
about 40 % of the variation for resistance to conidia inoculations
of the (chl+ nec+) pathotype.
A second population of 60
F2:3 families from the cross of the synthetic bread
wheat, W-7976 (resistant), and ND671 (susceptible), was screened
with necrosis toxin produced by a (chl- nec+) isolate. The families
segregated in a 1:2:1 ratio, suggesting a single recessive gene
controlling necrosis. Mapping of this population is in progress
to identify markers linked to necrosis resistance. This population
will be screened with chlorosis-producing isolates to determine
if chlorosis resistance is controlled by the same loci as in the
recombinant inbred population. (Faris, Anderson, Francl, and
Jordahl)
Linkage of RFLP markers to a wheat aluminum tolerance gene.
Our objectives were to 1)
determine the number of genes for aluminum (Al) tolerance and
chromosome location in BH 1146 and 2) identify DNA molecular markers
linked to Al tolerance gene(s). Aluminum tolerance/susceptibility
screening was performed on 98 recombinant inbred lines from the
cross `BH1146/Anahuac
75'
using two different methods of hydroponic nutrient solution.
Seedling roots were exposed to 46 ppm Al for 17 h or 1 ppm
Al for 72 h. Aluminum tolerance of the RI lines exhibited a bimodal
distribution using either method, suggesting genetic control by
a single gene. The correlation between methods was r = 0.73.
Eighty-three low-copy RFLP clones were screened for polymorphism
between the parents. Two markers closely linked to this Al tolerance
locus were detected on chromosome 4DL. Clone bcd1230 is located
at 1.1 cM from the gene and explains 83.2 % of the phenotypic
variation. Clone cdo1395 is 10.5 cM from the gene and explains
43.3 % of the phenotypic variation. Therefore, we conclude that
a major gene conditioning Al tolerance is present on chromosome
4DL in BH1146 (Riede and Anderson).
Mapping grain protein content from T. dicoccoides.
Genes from T. dicoccoides
conditioning high grain protein content have been introgressed
into hard red spring wheat germplasm. Recombinant inbred populations
from crosses between lines containing these genes and lower protein
HRS genotypes were evaluated for protein content in three environments.
We are in the process of screening RFLPs to find markers associated
with these genes (Mesfin, Frohberg, and Anderson).
Publications.
Ahn S, Anderson JA, Sorrells
ME, and Tanksley SD. 1993. Homoeologous relationships of rice,
wheat, and maize chromosomes. Mol Gen Genet 241:483-490.
Anderson JA, Sorrells ME,
Finney PL, and Tanksley SD. 1994. Molecular mapping of grain
quality traits in wheat. Plant Genome II Abstracts, San Diego,
CA. p. 15.
Anderson JA, Sorrells ME,
Finney PL, and Tanksley SD. 1994. Molecular mapping of grain
quality traits in wheat. In: Progress in genome mapping of wheat
and related species: Proceedings of the 4th Public Workshop of
the International Triticeae Mapping Initiative (Qualset CO and
McGuire P eds), San Diego, CA.
Anderson JA, Gill BS, Frary
A, Autrique JE, Sorrells ME, and Tanksley SD. 1994. RFLP analysis
of phylogenetic relationships in Triticum species. Abstracts
of the North American Wheat Workers Workshop, Kansas City, MO.
Anderson JA and Maan SS. 1994. Identification of a DNA marker linked to a species cytoplasm specific gene in wheat. Agron Abstr:120.
Riede CR and Anderson JA.
1994. Linkage of RFLP markers to a wheat aluminum tolerance
gene. Agron Abstr:127.
Durum wheat breeding and production in North Dakota.
E.M. Elias, S.Y. Xia, C.M. Rystedt, and P.W. Chee.
1994 durum wheat production.
North Dakota produced 73.1 million bushels (2.0 million MT) of
durum, which was 78 % of the total U.S. production. Producers
in North Dakota harvested 2.25 million acres (0.91 million ha),
an 18 % increase in acreage from 1993. The North Dakota average
yield of durum in 1994 was estimated at 32.5 bu/acre compared
to an average yield of 34.0 bu/acre in 1993. Renville was the
leading cultivar in acreage, 31 %, followed by Monroe, 25 %.
Diseases.
High moisture and moderate temperatures during the growing season
promoted heavy infection with foliar disease such as tan spot
(Pyrenophora tritici-repentis) and Septoria nodorum.
In 1994, an estimated 7.3 million bushels of durum wheat with
an approximate value of $40 million were lost because of scab
(Fusarium spp.) in North Dakota, (M. McMullen and J. Helm,
personal communications). In fact, except for the northwestern
parts of the state, most of the durum wheat crop was lost because
of scab. The durum wheat breeding nurseries at Prosper and Langdon,
North Dakota, were heavily infected with scab. There were no
differences among genotype in their reaction to scab, which made
selection very difficult. The Prosper breeding nursery was not
harvested because of scab.
Study on preharvest sprouting
in durum wheat.
Durum wheat is susceptible to sprouting during prolonged periods
of rainfall before harvest. Thus, the incorporation of preharvest
seed dormancy into durum wheat germplasm has become a breeding
objective. Two hundred sixteen lines from Canada, North Dakota,
Mexico, and the Middle East were evaluated at two North Dakota
locations in 1992 for preharvest dormancy. Ninety-two lines were
selected and evaluated at two locations in 1993. Seed dormancy
was assessed at two harvesting dates by placing single intact
spikes from each line in a rain-simulation chamber and by determining
the falling number and relative FONT SIZE=2 FACE="WP Greek Century""-amylase
activity of a line.
Significant correlations
occurred among the assessment methods. Results indicated the
presence of considerable variation among the lines evaluated.
Several durum lines had preharvest dormancy approaching the levels
found in the resistant hexaploid checks. The two lines `I.A.
CT12/Kato//IBIS/FG (IA)'
and `GTA/TC60/STK/3/Chahba
88 (GTA)'
did not differ significantly from the most resistant checks RL
4137 and `K32/Butte//Butte
86'.
These lines may provide useful germplasm to durum wheat breeders
working on preharvest sprouting resistance.
Release of Munich durum
wheat. Munich
was selected from the cross `D8030/D8016'
with the experimental line designation D8460. Munich has been
tested in replicated trials for agronomic, disease resistance,
and quality traits since 1985. It was entered in the Uniform
Regional Durum Nursery (URDN) in 1988. It has excellent yield
potential for the Langdon area, outyielding Renville by 10 % in
this area. Munich has 1.8 % higher yield than Sceptre, Renville,
Monroe, Vic, Medora, Rugby, and Lloyd when averaged across locations
in North Dakota (ND) and Canada in the URDN trails. Munich also
outyielded these cultivars when averaged across all test locations
in Canada, Minnesota, Montana, ND, and South Dakota in the URDN.
Munich has an average yield potential better than those of Sceptre,
Monroe, Vic, Medora, and Lloyd, but similar to that of Rugby and
slightly lower than that of Renville in North Dakota Research
Centers tests.
On average, Munich is lower in test weight than Vic and Rugby but higher than Monroe and Sceptre. It is medium in maturity and plant height with very strong straw. Munich is resistant to both leaf and stem rust diseases. Its leaf disease ratings for tan spot and septoria are similar to those of Rugby. It has a moderate level of resistance to scab.
In Carrington, ND, Munich
averaged 5.7 ppm vomitoxin level in comparison with 4.3 ppm for
Rugby, where the vomotoxin level in all cultivars and experimental
lines ranged from 3.4 to 14.0 ppm.
Munich is a strong gluten
durum cultivar that has protein content similar to those of Vic,
Renville, Monroe, and Sceptre. It has good color and semolina
extraction. Mixogram scores for Munich are slightly lower than
scores for Sceptre, Renville, Monroe, Vic, Medora, and Lloyd,
but higher than those for Rugby.
The variety was named Munich
to recognize the city of Munich, located in Cavalier County.
This area historically is in the durum production triangle in
North Dakota.
New Research.
Mr. P.W. Chee joined the durum wheat breeding project as a Ph.D.
graduate student working on molecular mapping of high grain protein
content in durum wheat. High protein durum wheat (Triticum
turgidum L. var. durum) cultivars are needed to satisfy
the needs of human nutrition and end-use quality consideration.
A few high grain protein germplasms have been identified in durum
wheat, including those from the wild relative T. dicoccoides.
Of particular importance to breeding programs is the 'Langdon'
(T. dicoccoides) substitution lines [LDN(DIC)] developed
by Joppa and Cantrell. LDN(DIC-6B) has a significantly higher
grain protein content than the recurrent parent cultivar Langdon.
The objective is to conduct a molecular analysis to map the chromosomal
location of the high protein genes in LDN(DIC-6B) in an agronomically
suitable background.
We have crossed the LDN (DIC)
substitution lines to the durum wheat cultivar Vic, to assess
the potential of using the LDN(DIC) lines in a breeding program
to derive lines with increased grain protein content. We also
have developed recombinant inbred populations derived from crosses
of LDN(DIC-6B) and `LDN(DIC-6B)/Vic'
to the durum wheat cultivar Renville. These inbred lines will
be used to generate a linkage map of chromosome 6B using RFLPs
and to collect phenotypic data for mapping analysis. Once the
high grain protein genes are identified, the closest RFLP markers
flanking the target gene will be sequenced from both ends, and
STS-PCR primer sets will be synthesized for them.
This work will provide a
better understanding of the genetics of the protein content trait
in wheat and will help directly in the production of improved
durum wheat cultivars. Durum wheat cultivars with high yield
and excellent quality measured as high protein content and gluten
strength are necessary to ensure the stability of high quality
durum wheat production, the international export market, and the
milling and national pasta industry.
Publications.
Chaney RL, Schniter AA, and
Elias EM. 1993. Genetics and soil factors related to Cd levels
in sunflower kernels and durum wheat grain. Agron Abstr:227.
Elias EM. 1993. Durum breeding
in North Dakota. In: The 1993 Regional Scab Forum. Moorhead,
MN. 3 Nov., 1993. p. 24.
Olmedo-Arcega OB. 1993.
Evaluation of recurrent selection for grain yield and its effect
on correlated traits in durum wheat. Ph.D. Thesis. 68 p.
Rystedt CM, Elias EM, and
Francle LJ. 1993. Inheritance of tan spot in three durum wheat
genotypes. Agron Abstr:101.
Xia SY and Elias EM. 1994.
Evaluation of pre-harvest dormancy in durum wheat. Agron Abstr:127.