J. G. Menzies

Cytological Evidence of an Active Role of Silicon in Wheat Resistance to Powdery Mildew (Blumeria graminis f. sp. tritici).

ABSTRACT Silicon (Si) amendments in the form of exogenously supplied nutrient solution or calcium silicate slag protect wheat plants from powdery mildew disease caused by the fungus Blumeria graminis f. sp. tritici. The most striking difference between Si- and Si+ plants challenged with B. graminis f. sp. tritici was the extent of epidermal cell infection and colonization by B. graminis f. sp. tritici. Histological and ultrastructural analyses revealed that epidermal cells of Si+ plants reacted to B. graminis f. sp. tritici attack with specific defense reactions including papilla formation, production of callose, and release of electron-dense osmiophilic material identified by cytochemical labeling as glycosilated phenolics. Phenolic material not only accumulated along the cell wall but also was associated with altered integrity of haustoria in a manner similar to localized phytoalexins as reported from other pathosystems. These results strongly suggest that Si mediates active localized cell defenses against B. graminis f. sp. tritici attack.

Silicon induced resistance in cucumber plants against Pythium ultimum

Abstract The effect of the amendment of nutrient solutions with soluble potassium silicate on the response of cucumber (cv. Corona) root and hypocotyl tissues infected by Pythium ultimum was examined by light and electron microscopy, and by energy dispersive X-ray analysis (EDX). Plants were grown in 0 or 1·7 m m Si-amended nutrient solutions, and root and hypocotyl samples were collected at different times after inoculation with P. ultimum . By 48 h after infection, striking differences in the expression of defence reactions were observed between Si-amended and Si-free cucumber plants. Treatment of plants with Si markedly stimulated the accumulation of an electron-dense, phenolic-like material in infected host tissues, and significantly increased the percentage of cells filled with this material. Fungal hyphae colonizing occluded host cells were seriously damaged, and were often reduced to empty hyphal shells. Additionally, Si-treated cucumber plants responded to P. ultimum infection by forming electron-dense layers along primary and secondary cell walls, as well as over pit membranes of xylem vessels. EDX analysis failed to reveal the presence of silica deposits in P. ultimum -infected plants grown in Si-supplemented media. Our results suggest that a relationship exists between Si treatment, resistance to P. ultimum attack, and expression of plant defence mechanisms.

Microsatellite tagging of the leaf rust resistance gene Lr16 on wheat chromosome 2BSc

Leaf rust, caused by Puccinia triticina, is one of the most damaging diseases of wheat worldwide. Lr16 is a widely deployed leaf rust resistance gene effective at the seedling stage. Although virulence to Lr16 exists in the Canadian P. triticina population, Lr16 provides a level of partial resistance in the field. The primary objective of this study was to identify markers linked to Lr16 that are suitable for marker-assisted selection (MAS). Lr16 was tagged with microsatellite markers on the distal end of chromosome 2BS in three mapping populations. Seven microsatellite loci mapped within 10 cM of Lr16, with the map distances varying among populations. Xwmc764 was the closest microsatellite locus to Lr16, and mapped 1, 9, and 3 cM away in the RL4452/AC Domain, BW278/AC Foremost, and HY644/McKenzie mapping populations, respectively. Lr16 was the terminal locus mapped in all three populations. Xwmc764, Xgwm210, and Xwmc661 were the most suitable markers for selection of Lr16 because they had simple PCR profiles, numerous alleles, high polymorphism information content (PIC), and were tightly linked to Lr16. Twenty-eight spring wheat lines were evaluated for leaf rust reaction with the P. triticina virulence phenotypes MBDS, MBRJ, and MGBJ, and analyzed with five microsatellite markers tightly linked to Lr16. There was good agreement between leaf rust infection type (IT) data and the microsatellite allele data. Microsatellite markers were useful for postulating Lr16 in wheat lines with multiple leaf rust resistance genes.

Unity hard red spring wheat

Unity is a hard red spring wheat that meets the end-use quality specifications of the Canada Western Red Spring class. Unity is the first spring wheat cultivar registered in Canada that contains the antibiosis resistance gene Sm1, which produces a product that reduces the palatability of developing seeds to wheat midge larvae (Sitodiplosis mosellana Gehin). Unity is a partial backcross derivative of McKenzie, using Clark as the donor of the Sm1 gene for midge resistance. Unity was found to be adapted to the eastern wheat growing regions of the Canadian prairies as represented in the Central Bread Wheat Cooperative Registration Test in 2004, 2005 and 2006. For registration testing, the performance of Unity was estimated using the varietal blend Unity VB, which consisted of 90% Unity and 10% Waskada. In comparison to the check cultivars (Katepwa, McKenzie, CDC Teal, AC Barrie, and Superb), Unity was the highest yielding cultivar overall; although not significant, Unity was 5% higher yielding than McKenzie. ...

Superb hard red spring wheat

Superb is a hard red spring wheat (Triticum aestivum L.) adapted to the wheat-growing regions of the Canadian prairies, and meets the end-use quality specifications of the Canada Western Hard Red Spring wheat class. Superb was evaluated in the Central Bread Wheat Cooperative Registration Test in 1997, 1998 and 1999. Superb yielded significantly more than the cultivars Neepawa, Roblin, AC Majestic, and 5500HR and slightly more than McKenzie. Superb was resistant to leaf and stem rust. Its disease reaction was “intermediate” to loose smut and common root rot, and moderately resistant to common bunt. Leaf spot reaction of Superb was similar to the checks and its reaction to Fusarium head blight was intermediate. Key words: Triticum aestivum L., Canada Western Hard Red, hard red spring wheat, cultivar description, yield, pre-harvest sprouting tolerance, disease resistance

Snowbird hard white spring wheat

Snowbird is a hard white spring wheat (Triticum aestivum L.) that meets the end-use quality and kernel visual distinguishability specifications of the Canada Western Hard White Spring Wheat class. Snowbird was evaluated in the Central Bread Wheat Cooperative Test in 1998, 1999 and 2000, and was found to be adapted to the wheat-growing regions of the Canadian prairies. Snowbird yielded more than the check cultivars Neepawa, Roblin, AC Majestic, McKenzie, Harvest, and AC Barrie but less than McKenzie. Snowbird is resistant to the prevalent races of leaf rust and moderately resistant to stem rust, loose smut and common root rot. Snowbird and Roblin exhibited similar levels of resistance to tanspot, Septoria tritici, and Septoria nodorum while its reaction to Fusarium head blight was similar to that of AC Barrie. Snowbird has similar grain and flour protein content as other check cultivars but had 1% less protein compared to Roblin. Key words: Triticum aestivum L., Canada Western Hard White, hard white spring...

Common bunt resistance gene Bt10 located on wheat chromosome 6D

Knowledge of the chromosomal location of disease resistance genes assists in their identification and classification. The determination of the chromosomal location in wheat of the common bunt (Tilletia tritici and T. laevis) resistance gene Bt10 was the goal of this study. Doubled haploid lines were developed from a cross between bunt susceptible Glenlea and bunt resistant AC Taber carrying Bt10. The doubled haploid lines were inoculated with T. tritici race T19, grown in a growth room and rated for bunt near maturity. A series of 50 wheat microsatellite markers were tested on DNA of the individual lines. The population segregated 1:1 for bunt reaction with clear separation between resistant and susceptible classes. A trait related DNA polymorphism generated by gwm469 located in chromosome 6D fit a 1:1 segregation. Combined segregation of bunt resistance and the gwm469 polymorphism differed significantly from a 1:1: 1:1 ratio with a preponderance of parental types confirming linkage of gwm469 with Bt10. T...

Waskada hard red spring wheat

Waskada is a hard red spring wheat that meets the end-use quality specifications of the Canada Western Red Spring wheat class. Waskada was found to be adapted to the wheat growing regions of the Canadian prairies based on data from the Central Bread Wheat Cooperative Registration Test in 2004, 2005 and 2006. In comparison with the check cultivars (Katepwa, McKenzie, CDC Teal, AC Barrie, and Superb), the grain yield of Waskada was similar to that of the best check in Manitoba and in Saskatchewan. Waskada matures 1 d later than AC Barrie and 1 d earlier than Superb. Waskada had similar height and lodging characteristics as Katepwa and McKenzie. The test weight of Waskada was 1.3 kg hL-1 higher than McKenzie, the best check. Waskada demonstrated moderate resistance to leaf rust but very good resistance to stem rust. Resistance to common bunt and loose smut was good, being similar to the more resistant checks Superb and Katepwa, respectively. Resistance to Fusarium head blight was better than the best check i...

A major quantitative trait locus conferring adult plant partial resistance to crown rust in oat

BackgroundCrown rust, caused by Puccinia coronata f. sp. avenae, is the most important disease of oat worldwide. Adult plant resistance (APR), based upon partial resistance, has proven to be a durable rust management strategy in other cereal rust pathosystems. The crown rust APR in the oat line MN841801 has been effective for more than 30 years. The genetic basis of this APR was studied under field conditions in three recombinant inbred line (RIL) populations: 1) AC Assiniboia/MN841801, 2) AC Medallion/MN841801, and 3) Makuru/MN841801. The populations were evaluated for crown rust resistance with the crown rust isolate CR251 (race BRBB) in multiple environments. The 6 K oat and 90 K wheat Illumina Infinium single nucleotide polymorphism (SNP) arrays were used for genotyping the AC Assiniboia/MN841801 population. KASP assays were designed for selected SNPs and genotyped on the other two populations.ResultsThis study reports a high density genetic linkage map constructed with oat and wheat SNP markers in the AC Assiniboia/MN841801 RIL population. Most wheat SNPs were monomorphic in the oat population. However the polymorphic wheat SNPs could be scored accurately and integrated well into the linkage map. A major quantitative trait locus (QTL) on oat chromosome 14D, designated QPc.crc-14D, explained up to 76% of the APR phenotypic variance. This QTL is flanked by two SNP markers, GMI_GBS_90753 and GMI_ES14_c1439_83. QPc.crc-14D was validated in the populations AC Medallion/MN841801 and Makuru/MN841801.ConclusionsWe report the first APR QTL in oat with a large and consistent effect. QPc.crc-14D was statistically significant in all environments tested in each of the three oat populations. QPc.crc-14D is a suitable candidate for use in marker-assisted breeding and also an excellent target for map-based cloning. This is also the first study to use the 90 K wheat Infinium SNP array on oat for marker development and comparative mapping. The Infinium SNP array is a useful tool for saturating oat maps with markers. Synteny with wheat suggests that QPc.crc-14D is orthologous with the stripe rust APR gene Yr16 in wheat.

Burnside extra strong hard red spring wheat

Burnside is a hard, red, spring wheat (Triticum aestivum L.) that meets the end-use quality specifications of the Canada Western Extra Strong wheat class. Burnside was evaluated in the Canada Western Extra Strong Wheat Cooperative Test in 2000, 2001, and 2002. In comparison with CWES cultivars Glenlea, Bluesky, AC Corinne, and CDC Walrus, Burnside had higher grain yields than Bluesky and AC Corinne, was similar to Glenlea and lower yielding than CDC Walrus. Burnside had maturity similar to Bluesky and was earlier maturing than Glenlea, AC Corinne, and CDC Walrus. Burnside is resistant to moderately resistant to prevalent races of leaf and stem rust and resistant to loose smut. End-use quality tests showed that Burnside had significantly higher grain protein content than the check cultivars.Key words: Triticum aestivum L., Canada Western Extra Strong, hard red extra strong spring wheat, cultivar description, yield, disease resistance