GrainGenes
A Database for Triticeae and Avena
Virulence of wheat leaf rust in Canada in 1995.
J.A. Kolmer.
Wheat leaf rust, caused by P. recondita f.
sp. tritici, was observed first in winter wheat plots at
Carmen, Manitoba, on 16 June. Rust infections were found on spring
wheat at Glenlea, Manitoba, on 25 June. Leaf rust infections were
widespread in fields of spring wheat in the Red River Valley of
Manitoba by the first week of July. Warm temperatures with frequent
dew periods at night provided favorable conditions for the rapid
increase and spread of leaf rust in Manitoba during the summer
of 1995. In the first week of August, nearly all spring wheat
fields in Manitoba that were surveyed were infected with leaf
rust to a varying degree, depending on the cultivar grown. Heavy
leaf rust infections were observed at plots in Carmen, Rosebank,
Portage, and Brandon. Plots of susceptible wheat at Indian Head
and Regina, in Saskatchewan, had light levels of leaf rust infection.
Leaf rust infections also were lighter in wheat fields in Saskatchewan
as compared to those in Manitoba.
In Manitoba, the cultivar Katepwa was affected severely
by rust, with infection levels between 50-90 %. The resistance
in Katepwa is no longer effective in years that are conducive
to rust epidemics. It should be considered for removal from the
recommended varieties for Manitoba. Cultivars AC Barrie, CDC Teal,
and Roblin had moderate levels of infection, between 10-40
%. More recent cultivars released by the Winnipeg Research Centre
(Pasqua, AC Minto, AC Cora, and AC Domain) were highly resistant,
with infection levels less than 5 %. The CPS cultivar AC Foremost
had high levels of infection, between 50-90 %, whereas
the cultivars AC Taber and AC Karma had moderate infection levels
between 10 and 50 %. Additional data on the leaf rust infection
in Canada in 1995 are presented in the following two tables.
Table 1. Predominant races (%) of Puccinia recondita f.sp. tritici in Canada in 1995.
____________________________________________________________________________
Virulence Manitoba/
Race formula Quebec Ontario Saskatchewan Alberta
____________________________________________________________________________
KBG 2a,2c,3,11 0.0 0.0 0.0 9.1
KFB 2a,2c,24,26 0.0 0.0 0.0 12.1
MBB 1,3 0.0 0.0 0.0 6.1
MBG 1,3,11 7.8 15.4 0.7 0.0
MBR 1,3,3ka,11,30 31.4 15.4 34.0 0.0
MDR 1,3,24,3ka,11,30 2.0 1.9 7.2 0.0
MJB 1,3,24,16 0.0 0.0 9.2 0.0
PBL 1,2c,3,3ka 7.8 44.2 0.0 0.0
TDB 1,2a,2c,3,24 9.8 1.9 3.3 15.2
TDG 1,2a,2c,3,11 9.8 1.9 11.8 15.2
Total Number Isolates 51.0 52.0 153.0 33.0
____________________________________________________________________________
Race codes are Prt nomenclature given in Long DL and Kolmer JA. 1989. A North American
system of nomenclature for P. recondita f.sp.
tritici. Phytopathology 79:525-529.
Table 2. Virulence frequencies (%) to isogenic `Thatcher' wheat lines with
single genes for leaf rust resistance in Puccinia recondita f. sp. tritici in Canada
in 1995.
______________________________________________________________
Resistance Manitoba/
gene Quebec Ontario Saskatchewan Alberta
______________________________________________________________
Lr1 92.0 100.0 98.0 78.0
Lr2a 26.0 8.0 24.0 58.0
Lr2c 55.0 60.0 24.0 58.0
Lr3 100.0 100.0 100.0 100.0
Lr9 0.0 0.0 0.0 0.0
Lr16 0.0 0.0 11.1 0.0
Lr24 26.0 8.0 49.0 76.0
Lr26 4.0 2.0 14.0 36.0
Lr3ka 67.0 71.0 62.0 0.0
Lr11 59.0 52.0 69.0 27.0
Lr17 0.0 0.0 2.0 0.0
Lr30 41.0 27.0 54.0 0.0
LrB 26.0 52.0 1.3 15.0
Lr10 92.0 94.0 96.0 100.0
Lr14a 80.0 46.0 100.0 100.0
Lr18 20.0 52.0 0.0 0.0
# of Isolates 51 52 153 33
______________________________________________________________
S. Haber, T. Aung, T.F. Townley-Smith, and E. Czarnecki.
In 1993, we reported that WSMV recently started to
pose a serious threat in those regions of the southeastern Canadian
prairies where spring wheat is grown in the vicinity of winter
wheat. Losses as high as 100 % occurred in popular hard red spring
wheat (CWRS) cultivars such as Laura and AC Minto (Haber and Townley-Smith
1993). Starting that year, we began a program, supported by the
Western Canada Grains Foundation, to screen and select adapted
western Canadian spring wheats with useful levels of disease tolerance.
We report here the use of doubled haploid technology to exploit
the best available WSMV tolerance present in adapted western Canadian
germplasm in developing superior, tolerant, breeding lines relatively
quickly.
Field trials from 1992 to 1995 confirmed that the
advanced CWRS breeding line, BW155 (= ND640; `Butte/Columbus'),
was the most promising source of WSMV tolerance already in the
CWRS breeding program. Parallel, controlled greenhouse trials
clearly showed that the superior field performance of BW155 under
WSM disease pressure correlated highly with the smaller adverse
effects it experienced with respect to height, tillering, maturity,
and seed set along with less pronounced visual symptoms.
To understand how the WSMV tolerance of BW155 was
determined and to move the BW155-conferred tolerance quickly into
desirable, but highly susceptible germplasm, we prepared DH plants
from F1 hybrids of `Laura/BW155.' Laura was chosen
as a recurrent parent not only because of its high susceptibility
to WSMV, but because it well represented the type of high-yielding,
high-quality CWRS wheat being developed for the southeastern Prairie
region where WSM was likely to be most acute.
If maximum advantage was to be gained from using
DH technology, it was essential to apply a selection regime that
would show clear-cut differences in WSMV tolerance among small
numbers of plants reared in a growth cabinet. Groups of eight
plants per tested line were inoculated with a virulent WSMV isolate
at the 2-leaf stage; four mock-inoculated plants of the same line
were reared in the same cabinet as controls. Each experiment included
identical treatments of Laura as a susceptible and BW155 as a
tolerant check. Plants were maintained in growth cabinets until
early heading, and then were transferred to the greenhouse to
mature.
All tested lines showed highly uniform responses
with respect to the effect of WSMV infection on height, maturity,
and seed yield compared to mock-inoculated controls. Close to
one-half of the DH lines, like Laura, were dwarfed severely by
WSMV infection at early growth stages and performed extremely
poorly with respect to seed yield at maturity. Among the other
half of the DH lines that, like BW155, experienced only moderate
dwarfing, three types of effects on seed yield were observed at
maturity. Some had much-delayed maturity and seed yields at maturity
intermediate between Laura and BW155; others had maturity similar
to BW155, but poor seed set, and Laura-like to intermediate yields;
and the remaining lines (close to an eighth of the total number
of DH lines from each cross) responded to WSMV infection similarly
to BW155.
In the first round, 25 DH lines were produced from
the cross `Laura/BW155.' Of the three DH lines with
performance similar to BW155, one (DH47) was selected for further
crossing. With improvements in DH technology, more than 60 DH
lines were generated from the cross `Laura/DH47'.
Among the 16 of these second-round DH lines tested to date,
two performed similarly to BW155 and DH47. If the tests of the
remaining second-round DH lines follow the same pattern as
that observed in the testing of first- and second-round DH lines
conducted thus far, we could conclude that BW155 likely possesses
three main determinants of WSMV tolerance.
Reference.
Haber S and Townley-Smith TF 1993. Developing tolerance
to wheat streak mosaic virus in spring wheats for western Canada.
Ann Wheat Newslet 39:121-123.
M.I.P. Kovacs, J.S. Noll, G. Dahlke, and D. Leisle.
The usefulness of cooked pasta disc viscoelasticity
(PDV) to predict pasta cooking quality in the durum wheat breeding
program was evaluated. PDV showed high correlations with the mixograph,
SDS-sedimentation, and cooked gluten viscoelasticity tests. PDV
results indicate that the test is useful in breeding programs,
because it requires small quantities of sample, is simple, and
more closely mimics rheological tests used on the final product,
pasta.
Durum wheat quality: comparison of chemical and rheological screening tests with sensory analysis.
M.I.P. Kovacs, L.M. Poste-Flynn, D. Leisle, G. Dahlke, J.S. Noll, S.M. Woods, and G.S. Butler.
Various chemical and physical screening tests to predict pasta cooking quality in a durum wheat breeding program were evaluated using sensory methods. Values for mixing total energy and mixing peak height obtained using a mixograph were the best predictors for chewiness and firmness. None of the tests correlated with adhesiveness to teeth. Because the mixograph test is simple, requires relatively small sample size, and gives the results that are highly correlated with sensory data, it is the most useful test to predict the end use quality of durum wheat in a breeding program.