Races Of Leaf Rust Research Articles

‘Savoy’, an Adapted Soft Red Winter Wheat Cultivar for Georgia and the Southeast Regions of the United States

Soft red winter wheat (SRWW) (Triticum aestivum L.) is a major crop in Georgia and the southeastern region of the United States. Despite a decrease of wheat acreages in this region, about 100,000 ha were grown to SRWW in Georgia in 2015. To capture and maximize regional market value of wheat, the new released cultivars must have high yield potential, excellent resistance levels to predominant diseases and insects, and good quality. Therefore, the major goal of the SRWW breeding program at the University of Georgia (UGA) is to develop and release SRWW cultivars adapted to the southeastern wheat region with high yield, quality, and pest resistance. ‘Savoy’ (Reg. No. CV‐1135, PI 676043) is a SRWW cultivar developed by the small grains breeding program at UGA in cooperation with the SUNGRAINS and released by the UGA College of Agricultural and Environmental Sciences in 2015. Savoy was subsequently licensed to CPS DYNA‐GRO Seed Company. Savoy was released because it is widely adapted to Georgia and the US Southeast. It has high grain yield, good resistance to races of leaf rust and stripe rust predominant in Georgia and the Southeast. Savoy possesses the H13 gene that confers resistance to predominant biotypes of Hessian fly in Georgia and the Southeast. It has good resistance to powdery mildew and Soil‐borne wheat mosaic virus. Savoy is moderately susceptible to Fusarium head blight, or scab. It also has high grain volume weight and acceptable SRWW milling and baking quality.

AAC Penhold Canada Prairie Spring Red Wheat

AAC Penhold, an awned hard red spring wheat (Triticum aestivum L.) cultivar, yielded significantly more grain than check cultivar 5700PR while maturing 2 d earlier and was 7.5 cm shorter in stature. The seed size was significantly larger than 5700PR and 5701PR, with a test weight significantly heavier than both checks. AAC Penhold expressed resistance to prevalent races of leaf rust and common bunt and moderate resistance to Fusarium head blight and stem rust. AAC Penhold had higher grain and flour protein than the checks and improved Hagberg falling number, amylograph viscosity, and water absorption. AAC Penhold is eligible for grades of the Canada Prairie Spring Red wheat market class.

Assessment of genetic diversity of coffee leaf rust pathogen Hemileia vastatrix using SRAP markers

AbstractCoffee leaf rust caused by the fungus Hemileia vastatrix (Berk and Br.) is a major disease occurring in coffee plantations. Although the rust fungus exists in different physiological races, the genetic difference between them is meagrely understood. In this study, genetic diversity of 14 identified and two unidentified leaf rust races was determined by sequence‐related amplified polymorphism (SRAP) markers. Of 48 SRAP primer pairs tested, 35 primers are polymorphic and generated 347 distinct scorable fragments. The number of fragments ranged from 4 to 18 with a mean of 9.97 fragments per primer combination. Of the total 347 amplified fragments, 185 fragments (53.31%) are polymorphic with an average of 5.41 fragments per primer combination. The average resolving power (Rp) and the average polymorphism information content (PIC) of the 35 SRAP primer combinations were 13.60 and 0.356, respectively. Of 35 SRAP primer pairs, 15 primer pairs were more informative and generated 25 unique fragments, which are useful for race discrimination. The study demonstrated the existence of genetic variability among various leaf rust races and this information will be helpful in coffee breeding programmes.

Molecular Cytogenetic Characterization of two Triticum-Secale-Thinopyrum Trigeneric Hybrids Exhibiting Superior Resistance to Fusarium Head Blight, Leaf Rust, and Stem Rust Race Ug99.

Fusarium head blight (FHB), leaf rust, and stem rust are the most destructive fungal diseases in current world wheat production. The diploid wheatgrass, Thinopyrum elongatum (Host) Dewey (2n = 2x = 14, EE) is an excellent source of disease resistance genes. Two new Triticum–Secale–Thinopyrum trigeneric hybrids were derived from a cross between a hexaploid triticale (X Triticosecale Wittmack, 2n = 6x = 42, AABBRR) and a hexaploid Triticum trititrigia (2n = 6x = 42, AABBEE), were produced and analyzed using genomic in situ hybridization and molecular markers. The results indicated that line RE21 contained 14 A-chromosomes, 14 B-chromosomes, three pairs of R-chromosomes (4R, 6R, and 7R), and four pairs of E-chromosomes (1E, 2E, 3E, and 5E) for a total chromosome number of 2n = 42. Line RE62 contained 14 A-chromosomes, 14 B-chromosomes, six pairs of R-chromosomes, and one pair of translocation chromosomes between chromosome 5R and 5E, for a total chromosome number of 2n = 42. At the seedling and adult growth stages under greenhouse conditions, line RE21 showed high levels of resistance to FHB, leaf rust, and stem rust race Ug99, and line RE62 was highly resistant to leaf rust and stem rust race Ug99. These two lines (RE21 and RE62) display superior disease resistance characteristics and have the potential to be utilized as valuable germplasm sources for future wheat improvement.

‘GA 03564‐12E6’: A High‐Yielding Soft Red Winter Wheat Cultivar Adapted to Georgia and the Southeastern Regions of the United States

Soft red winter wheat (SRWW) (Triticum aestivum L.) is a major crop in the southeastern region of the United States and in Georgia. Although wheat acreages have been decreasing in Georgia and the SE region in recent years, more than 100,000 ha were grown to SRWW in 2015. Newly released cultivars must have high yield potential, excellent resistance levels to predominant diseases and insects, and good quality to capture and maximize regional market value. One objective of the SRWW breeding program at the University of Georgia (UGA) is to develop and release SRWW cultivars adapted to the SE wheat region with high yield, quality, and pest resistance. ‘GA 03564‐12E6’ (Reg. No. CV‐1122, PI 677366) SRWW was developed by the UGA small grains breeding program and the SUNGRAINS cooperative and released by the UGA College of Agricultural and Environmental Sciences and licensed to Limagrain Cereal Seeds as L11544 in 2015. GA 03564‐12E6 was released primarily for its wide adaptation to the SE region with high grain yield, excellent Hessian fly resistance, and excellent grain volume weight. Additionally, GA 03564‐12E6 has good resistance to races of leaf rust and stripe rust predominant in Georgia and the SE United States. It has good resistance to powdery mildew (caused by Blumeria graminis f. sp. tritici) and Soil‐borne wheat mosaic virus and has acceptable SRWW milling and baking quality. However, it is susceptible to Fusarium head blight (FHB) or scab [caused by Fusarium graminearum Schwabe; teleomorph Gibberella zeae (Schwein.) Petch].

Identification of microsatellites linked to Lr47

Leaf rust resistance gene Lr47 is located within a interstitial segment of Triticum speltoides Taush. 7S chromosome translocated to the short arm of chromosome 7A of bread wheat. This gene is resistant against currently predominant races of leaf rust from Argentina. The objectives of this study were to identify microsatellites linked to this source of resistance as a potential tool to introgress this source of resistance. Isogenic lines with and without Lr47 developed from 10 cultivars/breeding lines as well as 10 microsatellites previously mapped in 7AS chromosome were used in this study. Microsatellite gwm 60 was the only marker that co-segregated completely linked to Lr47 . These data indicate that gwm 60 could be a valuable marker to introgress Lr47 in wheat germplasm.

AAC NRG097 Canada Western Special Purpose Spring Wheat

AAC NRG097, a hard red spring wheat (Triticum aestivum L.), was developed at the Swift Current Research and Development Centre of Agriculture and Agri-Food Canada, in Swift Current, SK. AAC NRG097 has grain yield and time to maturity within the range of the checks, a semidwarf stature, and heavier seed mass than the checks. It expressed resistance to prevalent races of both leaf rust and common bunt, while expressing an intermediate level of resistance to Fusarium head blight. It received registration no. 7567 from the Variety Registration Office, Plant Production Division, Canadian Food Inspection Agency (CFIA) on 24 July 2014. AAC NRG097 was granted Plant Breeders’ Rights Certificate no. 5089 by the Plant Breeders’ Rights Office, CFIA on 7 Aug. 2015. It is eligible for grades of Canada Western Special Purpose.

AAC Ryley Canada Prairie Spring Red Wheat

AAC Ryley is an awned semidwarf hard red spring wheat (Triticum aestivum L.) that yielded significantly more grain than check cultivar 5700PR while maturing 1.9 d earlier and growing 5 cm taller. The seed size was significantly larger than 5700PR and 5701PR but the test weight was significantly lower than both checks. AAC Ryley expressed resistance to prevalent races of leaf rust, stem rust, and common bunt. AAC Ryley expressed intermediate resistance to loose smut and moderate susceptibility to Fusarium head blight. AAC Ryley is eligible for grades of Canada Prairie Spring Red wheat.

CDC Precision Durum Wheat

CDC Precision durum wheat is adapted to the durum production area of the Canadian prairies. This conventional height durum wheat cultivar combines high grain yield potential with high grain pigment and low grain cadmium. CDC Precision is resistant to prevalent races of leaf, stem and stripe rust, and common bunt and expresses end-use quality suitable for the Canada Western Amber Durum (CWAD) class.

AAC Brandon Hard Red Spring Wheat

AAC Brandon hard red spring wheat (Triticum aestivum L.) has grain yield and time to maturity within the range of the check cultivars: Katepwa, Laura, Lillian, Carberry, and CDC Kernen. AAC Brandon has an awned spike, a low lodging score indicative of strong straw, and a short plant stature typical of a semidwarf. AAC Brandon expressed resistance to prevalent races of leaf, stem, and stripe rust, and moderate resistance to fusarium head blight and loose smut. Compared with the five Canada Western Red Spring check cultivars, AAC Brandon has improved flour yield and lower flower ash. AAC Brandon is eligible for grades of Canada Western Red Spring.

CDC Alloy durum wheat

CDC Alloy durum wheat is adapted to the durum production area of the Canadian prairies. This conventional height durum wheat cultivar combines high grain yield potential with high grain pigment and protein concentrations and low grain cadmium. CDC Alloy is resistant to prevalent races of leaf, stem and stripe rust, and common bunt and expresses end-use quality suitable for the Canada Western Amber Durum (CWAD) class.

CDC Dynamic durum wheat

CDC Dynamic durum wheat is adapted to the durum production area of the Canadian prairies. This conventional height durum wheat cultivar combines high grain yield potential and protein concentration with high grain pigment and low grain cadmium. CDC Dynamic is resistant to prevalent races of leaf, stem, and stripe rust, and common bunt and expresses end-use quality suitable for the Canada Western Amber Durum (CWAD) class.

Wheat mutant MNR220 delays haustoria formation during leaf rust pathogenesis at the seedling stage

This study reports further characterization of the defence mechanism of an EMS-induced mutant (MNR220) that displays enhanced resistance to leaf rust, stem rust, stripe rust and powdery mildew diseases. The broad-spectrum resistance of the mutant was characterized by a microscopy study and additional race screenings of two rust pathogens. The mutant displayed less disease severity in response to all the races tested, when compared with the wild-type. The microscopy study of the pathogenesis of a leaf rust race PBJJG on the mutant revealed that the resistance was first evident at the pre-haustorial stage; formation of haustoria was significantly delayed or inhibited in the mutant compared with the wild-type. The mutant displayed microscopic level of cell death even in the absence of any pathogens. These findings suggest that MNR220 mediates a spontaneous cell death that delays the infection process by delaying haustoria formation of the pathogen.

Adult plant resistance to Puccinia triticina in a geographically diverse collection of Aegilops tauschii

Despite extensive genetics and breeding research, effective control of leaf rust caused by Puccinia triticina Eriks. and an important foliar disease of wheat, has not been achieved. This is mainly due to the widespread use of race-specific seedling resistance genes, which are rapidly overcome by new virulent races. There is increased emphasis now on the use of race-nonspecific adult plant resistance (APR) genes for durable control of leaf rust. The objective of this study was the evaluation of Aegilops tauschii Coss. (the D-genome donor of bread wheat) for APR, previously known to be a rich source of seedling resistance genes to leaf rust. A geographically diverse collection of A. tauschii maintained by the Wheat Genetics Resource Center was evaluated for APR in the field with a leaf rust composite culture of predominant races. Out of a total of 371 A. tauschii accessions, 50 with low to moderate levels of disease severity were subsequently tested at the seedling stage in the greenhouse with four races and one composite culture of leaf rust. Nine accessions displayed moderate resistance to one or more races of leaf rust at the seedling stage. The remaining 41 seedling-susceptible accessions are potential sources of new APR genes. Accessions from Afghanistan only displayed APR whereas both seedling resistance and APR were common in the Caspian Sea region (Iran and Azerbaijan). The APR in these newly identified A. tauschii accessions will be further characterized for novelty, effectiveness, and race-specificity.

AAC Elie hard red spring wheat

AAC Elie hard red spring wheat (Triticum aestivum L.) has grain yield and time to maturity within the range of the checks. AAC Elie has an awned spike, a low lodging score indicative of strong straw, and a short plant stature typical of a semidwarf. These traits were comparable to the check Carberry. AAC Elie expressed resistance to prevalent races of leaf and stem rust, and intermediate resistance to fusarium head blight, yellow rust, common bunt, and loose smut. Compared with the five Canada Western Red Spring checks, AAC Elie has improved flour yield, and lower flower ash. AAC Elie is eligible for grades of Canada Western Red Spring.

AAC Proclaim general purpose spring wheat

Randhawa, H. S., Graf, R. J., Fox, S. L. and Sadasivaiah, R. S. 2015. AAC Proclaim general purpose spring wheat. Can. J. Plant Sci. 95: 1265–1269. AAC Proclaim is a soft red spring wheat cultivar eligible for the Canada Western General Purpose (CWGP) wheat class. Evaluated in 18 trials grown over 2 yr in the General Purpose Wheat Cooperative Registration trial, AAC Proclaim yielded significantly lower than the CWGP checks, AC Andrew and Pasteur, and was 1 and 5 d earlier maturing, respectively. AAC Proclaim was significantly taller than the checks, but had similar straw strength. Test weight was higher than the checks and kernel mass was similar to AC Andrew. Based on visual assessments and deoxynivalenol testing over 3 yr, AAC Proclaim was rated as resistant to Fusarium head blight. It also expressed resistance to the prevalent races of leaf rust and moderate resistance to the prevalent races of stem rust and loose smut. AAC Proclaim showed susceptibility to infection by stripe rust and common bunt.

Molecular Markers Identification of Leaf Rust Resistant Genes Lr19, Lr21, Lr24, Lr47 and Lr51 in Selected Egyptian Wheat Cultivars

Leaf rust, caused by Puccinia triticina is a common and widespread disease of bread wheat (Triticum aestivum L.), in Egypt. Host resistance is the most economical, effective and ecologically sustainable method for controlling the disease. Molecular markers help to determine leaf rust resistance genes (Lr genes) that may be present in a large group of wheat germplasm. The objective of this study was to evaluate and detect leaf rust resistance genes in Egyptian wheat cultivars. Ten out of fifteen cultivars were resistance to leaf rust disease in four locations i.e., Dakahlia, Kafr el-Sheikh, Beheira and Sharqia during seasons 2011/2012 and 2012/2013. As for, using specific SSR primers proved that Lr19 was present in five cultivars i.e., Sakha-95, Gemmeiza-9, Gemmeiza-10, Misr-1 and Misr-2. Lr21. Lr24, Lr47, and Lr51 were detected in all tested cultivars. These genes should be taken into consideration in wheat breeding programs for successful rust resistance. Furthermore these materials can be used as a parent for plant breeders to add new effective resistance genes to their breeding materials because of the dynamic change of leaf rust races which can breakdown the resistance.

CDC Carbide durum wheat

Pozniak, C. J. and Clarke, J. M. 2015. CDC Carbide durum wheat. Can. J. Plant Sci. 95: 1007–1012. CDC Carbide durum wheat is adapted to the durum production area of the Canadian prairies. This conventional-height durum wheat cultivar combines high grain yield potential with high grain pigment and protein concentrations, and low grain cadmium. CDC Carbide carries the Sm1 gene conferring resistance to the Orange Wheat Blossom Midge [Sitodiplosis modellana (Gehin)]. CDC Carbide is resistant to prevalent races of leaf, stem and stripe rust, and common bunt, and expresses end-use quality suitable for the Canada Western Amber Durum class.

AAC Innova general purpose spring wheat

Randhawa, H. S. Graf, R. J. and Sadasivaiah, R. S. 2015. AAC Innova general purpose spring wheat. Can. J. Plant Sci. 95: 787–791. AAC Innova is a high-yielding spring wheat cultivar eligible for the Canada Western General Purpose (CWGP) wheat class. Based on 32 site-years of testing over 3 yr in the General Purpose Wheat Cooperative Registration trial (2008–2010), AAC Innova yielded 4% higher than AC Andrew and was 1 d later in maturity. Compared with AC Andrew, AAC Innova had similar test weight and the soft white kernels were slightly larger. AAC Innova was resistant to the prevalent races of leaf rust and was resistant to moderately resistant to stem rust and leaf spotting diseases. It was susceptible to common bunt, loose smut and Fusarium head blight.

A QTL on chromosome 5BL in wheat enhances leaf rust resistance of Lr46

Combinations of effective leaf rust resistance genes that condition resistance to many leaf rust races are key to the development of wheat cultivars with long-lasting resistance to leaf rust caused by Puccinia triticina. A population of F6 recombinant inbred lines (RILs) derived from the cross ‘Thatcher*3/Americano 25e’ was evaluated for segregation of adult plant leaf rust resistance in three field plot tests and in a greenhouse test. A genetic map was constructed with 243 diversity array technology markers. Significant effects for reduction in leaf rust severity were found on chromosomes 1BL and 5BL. The sequence-tagged site marker csLV46, closely linked to Lr46, mapped to the logarithm of odds peak on chromosome 1BL, indicating that the RILs were likely segregating for this adult plant resistance gene. Lines with csLV46 had an average leaf rust severity of 35 % in the four tests. RILs with the resistance on chromosome 5BL designated as QLr.cdl-5BL had an average leaf rust severity of 47 %. RILs with both csLV46 and QLr.cdl-5BL had an average leaf rust severity of 22 %, close to the Thatcher*2/Americano 25e parental line. Lines that lacked both csLV46 and QLr-5BL had an average severity of 56 %. The QLr.cdl-5BL region enhanced the leaf resistance conditioned by Lr46 in an additive manner.