AGICULTURE AND AGRI-FOOD CANADA
Cereal Research Centre, 195 Dafoe Rd, Winnipeg, Manitoba, Canada, R3T 2M9.
|Province||Wheat||Hectares seeded||Metric tons produced|
J.D. Procunier and J. Gilbert.
For the complex genetic system of FHB resistance in wheat, three additive resistance genes on separate chromosomes have been identified using a doubled-haploid, segregating population. Each resistance gene contributes about 25-40 % of the total resistance found in Sumai 3. User-friendly and codominant markers linked to all three resistance loci have been developed. All three genes can be detected simultaneously by multiplexing. Seed material can be tested, thus eliminating the lengthy growing period prior to conventional inoculation testing. The type II (spreading) and type I (initial infection) resistance genes have been identified tentatively.
Multiple markers for each resistance gene allowed the graphical genotyping of multiple alleles flanking these genes. Graphical genotyping of numerous resistant and susceptible lines will determine if these markers are informative in these lines. The cosegregation of the FHB-resistant phenotype and these markers has been shown for at least five generations; thus, the markers can track the resistance genes. The markers are being used by breeders to pyramid FHB-resistance genes into elite cultivars.
S. Haber, B.O. Gillis, and J. Clarke.
The current expansion of winter wheat acreage in the black soils of eastern Saskatchewan and southern Manitoba raises the risk of WSMV infection of durum wheat grown near winter wheat fields. All wheat cultivars currently registered for use in western Canada are susceptible to WSMV, and durum wheats are especially vulnerable to severe losses (Haber et al. 1997).
Although the Wsm1 gene for WSMV resistance has been exploited
successfully in the development of resistant elite, bread wheat
lines (Seifers et al. 1995; Haber, unpublished), it will be difficult
to deploy this gene in a durum wheat background without affecting
quality. The Wsm1 gene available for crossing into tetraploid
durum germ plasm is on the short arm of A. intermedium
chromosome 4Ai-2 translocated onto wheat chromosome 4A (T4A·4Ai-2S),
where the alien chromatin could cause quality defects.
Therefore, we have examined whether useful levels of WSMV tolerance exist in at least some of the elite accessions currently being tested in western Canadian, durum wheat breeding programs. Fifty lines, including Canadian, American, European, and Australian durum wheat cultivars and advanced breeding lines were screened under WSM-disease pressure in a replicated, indoor trial. Plants were rub-inoculated at the 6-leaf stage with a virulent WSMV isolate, and symptoms read at 14, 19, and 23 days postinoculation and at maturity. Symptoms were scored on a 1 (immune) to 9 (dead) scale, and hexaploid spring wheats with known responses to WSMV used as checks were Laura (susceptible, 8), AC Elsa (moderately susceptible, 6), BW155 (tolerant, 3.5), Pai Toborichi (resistant, 2), and +Wsm1-AC Elsa (immune, 1).
All of the tested North American and European durum wheat cultivars were susceptible or highly susceptible. However, Wollaroi, an Australian cultivar with a T1B·1R translocation, and a line derived from a cross between Wollaroi and Souri, a Tunisian landrace, responded with mild symptoms, similar to the hexaploid checks BW155 and Pai Toborichi. A subsequent test confirmed these observations. In an additional test in which temperature was raised to 25°C after 14 days postinoculation, the two apparently resistant durum lines developed severe symptoms, and Wollaroi died before heading. Temperature-sensitive resistance to WSMV infection has been observed in winter wheat (Seifers et al. 1995) in which Wsm1 is translocated onto the long arm of chromosome 4D (T4DL·4Ai-2S) and in the spring wheat cultivar Pai Toborichi (Haber, unpublished).
We are now evaluating this source of WSMV resistance in a range
of western Canadian durum wheat backgrounds to determine its inheritance
and its effectiveness when deployed in elite germ plasm.
AGICULTURE AND AGRI-FOOD CANADA
Crops and Livestock Research Centre, P.O. Box 1210, Charlottetown, Prince Edward Island, Canada.
A large area of the Maritimes experienced a severe drought, so much so, that some fields were not harvested. Grain yields were about 30-50 % of normal. Diseases and pests were not problems because of the very dry season. DON levels in wheat and barley samples were 0.4 ppm or less. Although cereal growers had difficulty in achieving a 12.5-13.5 % protein content required for milling wheats in 1998, this was not a problem in 1999.
The registration of the following wheat cultivars is expected in the spring of 2000 based on support from Maritime and Ontario Cereal Cultivar Registration Committees:
AC Sampson (WW 12) is a hard red winter milling wheat (pedigree: AC Winsloe*1/Flamura 80) for eastern Canada. AC Sampson is the first such variety developed in Maritime breeding programs. This variety has good winter hardiness and improved resistance to powdery mildew and has a higher grain yield than the milling and feed check cultivars. The loaf volume is superior to that of Karat and Fundulea, but stability is slightly lower than that of Karat.
AC Hartland (AW 305) is a high-yielding, spring feed wheat (pedigree: Ankra/Kolibri/2/ (Thatcher//Rescue/Chinook/3/Neepawa/4/Opal/Vendel) with superior yield in all regions of eastern Canada, of medium-late maturity, resistant to powdery mildew, and resistant to lodging.
AC Helena (AW 356) is a white-chaffed, awned, high-yielding, spring milling wheat (pedigree: QW534.40/3/Gamenya/Kolibri//Consens) with good yield in Ontario and the Maritimes, improved resistance to BYDV and powdery mildew, but susceptible to leaf and stem rust. AC Helena has strong gluten.
AC Walton (AW 197) is a hard red, spring milling wheat (pedigree: N.Bozu/2/Kolibri/Janus/3/Opal /Glenlea) that is being moved from interim to full registration for the Maritimes. This cultivar has excellent yield, similar to that of the high-yielding feed wheat checks, and is resistant to powdery mildew. However, production of this cultivar in the Maritimes requires special nitrogen management for protein.