2015 BGRI Poster Abstracts

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Displaying 231 - 240 of 415

Reactions of spring wheat genotypes in crossing block nursery to stem, leaf, and stripe rust

Rusts (Puccinia spp.) are the most significant disease affecting wheat yield and quality in Turkey. Knowing the resistance status of wheat genotypes in crossing program is an important issue for breeding programs. The aim of the study was to determine of the resistance of the 106 wheat genotypes consisting of Crossing Block Spring Wheat (CBSW) nursery developed by the International Winter Wheat Improved Project (IWWIP). For this purpose, adult plant and seedling test were conducted for yellow rust while only seedling test were conducted for leaf and stem rust. Evaluations were carried out at the research facilities of CRIFC at İkizce and Yenimahalle in Ankara in the 2014 season. For adult plant reactions; the genotypes were inoculated with local Pst populations (virulent on Yr2,6,7,8,9,25,27,Sd,Su,Avs). Stripe rust development on each entry were scored using the modified Cobb scale when the susceptible check Little Club had reached 80S infection severity in June, 2014. Coefficients of infections were calculated and values below 20 were considered to be resistant. For seedling test; the seedling was inoculated with local Pgt (avirulent on Sr24, Sr26, Sr27, and Sr31), Pt (avirulent on Lr9, Lr19, Lr24, and Lr28) and Pst populations. Stripe, leaf and stem rust development on each entry were scored after 14 days with 0-4 and 0-9 scale for leaf-stem rust and yellow rust, respectively. In seedling stage, thirty nine (37%), 47 (44%), and 20 (19%) genotypes were resistant to local Pgt, Pt, and Pst populations, respectively. In adult plant test, 46 (43%) genotypes were resistant to Pst.  The resistance genotypes to stem, leaf, and stripe rust were determined with this research.

 

Primary Author: Mert, The Central Research Institute for Field Crops, Turkey

Keywords: Turkey, stem rust, stripe rust, leaf rust

Responses of some Turkish winter durum wheat genotypes in preliminary yield trials to stem, leaf and stripe rusts

Durum wheat is second important crop after bread wheat and it was grown as spring and winter type in Turkey. Rusts are the most important diseases limiting durum wheat production in Turkey. The aim of the study was determining of the resistance of the 232 Turkish winter durum wheat genotypes in preliminary yield trials developed by the Central Research Institute for Field Crops (CRIFC) to rusts.  For this purpose, adult plant and seedling test were conducted for yellow rust while only seedling test were conducted for leaf and stem rust. Evaluations were carried out at the research facilities of CRIFC at İkizce and Yenimahalle in Ankara in the 2014 season. For adult plant reactions; the genotypes were inoculated with local Pst populations (virulent on Yr2,6,7,8,9,25,27,Sd,Su,Avs). Stripe rust development on each entry were scored using the modified Cobb scale when the susceptible check cv. Little Club had reached 80S infection severity in June, 2014. Coefficients of infections were calculated and values below 20 were considered to be resistant. For seedling test; the seedling was inoculated with local Pgt (avirulent on Sr24, Sr26, Sr27, and Sr31), Pt (avirulent on Lr9, Lr19, Lr24, and Lr28) and Pst populations. Stripe, leaf and stem rust development on each entry were scored after 14 days with 0-4 and 0-9 scale for leaf-stem rust and yellow rust, respectively. In seedling stage, 141(65%), 41(18%), and 114 (49%) genotypes were resistant to local Pgt, Pt, and Pst populations, respectively. In adult plant test, 21 (9%) genotypes were resistant to Pst.  The resistance genotypes to stem, leaf, and stripe rust were determined with this research.

Primary Author: Mert, Central Research Institute for Field Crops, Turkey

Keywords: Turkey, durum wheat

The reactions of winter wheat stem rust resistance sources to stem, leaf and stripe rusts in 2014

Stem rust still remains an important threat to wheat with new races such as Ug99. In 2012 main season, some genotypes developed by Central Research Institute for Field Crops were sent to Kenya for screening to Ug99 and WWSRRN (winter wheat stem rust resistance nursery) was organized with resistant genotypes according to result. Addition to Ug99, the resistances to local stem rust, leaf rust and yellow rust races are important.  The aim of this study was  to determine reactions of 99 genotypes in WWSRRN  to local rust population in the seedling stage (for PSt, Pgt and Pt) and adult plant stage (for Pst and Pgt) at the research facilities of CRIFC in Ankara and Kastamonu (stem rust) during 2014 season. For adult plant test; the genotypes were inoculated with local Pst populations (virulent on Yr2,6,7,8,9,25,27,Sd,Su,Avs) and local Pgt populations (avirulent on Sr24, Sr26, Sr27, and Sr31). Stripe and stem rust development on each entry were scored using the modified Cobb scale when the susceptible check Little Club had reached 80S infection severity in June and August 2014, respectively. Coefficients of infections were calculated and values below 20 were considered to be resistant. For seedling test; the seedling was inoculated with local Pgt, Pt (avirulent on Lr9, Lr19, Lr24, and Lr28) and Pst populations. Stripe, leaf and stem rust development on each entry were scored after 14 days with 0-4 and 0-9 scale for leaf-stem rust and yellow rust, respectively. Thirty seven (37%) (seedling) genotypes and 39 (39%) (adult stage)  genotypes were resistant to local Pgt, 35 (35%) (seedling) were resistant to the local Pt, and 55 (56%) (seedling) and 59 (60%) (adult stage) genotypes were resistant to the local Pst populations. The resistance sources to stem, leaf, and stripe rust were determined with this research.

 

Primary Author: Mert, The Central Research Institute for Field Crops, Turkey

Keywords: Turkey, winter wheat

Molecular-genetic dissection of rice nonhost resistance to wheat stem rust

Rust diseases remain a significant threat to the production of most cereals including wheat. New sources of resistance are continually sought by breeders to combat the emergence of new pathogen races. Rice is atypical in that it is an intensively grown cereal with no known rust pathogen. The resistance of rice to cereal rust diseases is referred to as nonhost resistance (NHR), a resistance mechanism that has only recently become genetically tractable. In this report, the mechanisms of rice NHR to wheat stem rust and other cereal rust diseases are explored and the potential for transferring this durable disease resistance to wheat is considered. Approaches being undertaken for the molecular-genetic dissection of rice NHR to rust are described.

Primary Author: Michael Ayliffe, CSIRO Plant Industry, Australia

Keywords:

Cytogenetic manipulation to enhance the utility of alien resistance genes

Although many wild relatives in the Triticeae tribe have been exploited to transfer stem rust resistance genes to wheat, the derived germplasms have often not been immediately useful in wheat breeding programs. Too frequently, large chromosome segments surrounding desirable genes also harbor deleterious genes that result in unacceptable yield or quality. Recombination between chromosomes of wheat and chromosomes of distant relatives is very rare due to genetic restrictions on chromosome pairing in polyploid wheat. However, chromosome pairing can be manipulated by utilizing mutant stocks that relax this tight genetic control. The ph1b mutant produced by E.R. Sears over 30 years ago is an invaluable chromosome engineering tool, readily employed in the age of high-throughput molecular genetics. Shortened translocations have already been produced for stem rust resistance genes Sr26 and SrR using ph1b-induced homoeologous recombination. We are currently using induced-homoeologous recombination to reduce the sizes of alien chromosome segments surrounding TTKSK-effective genes Sr32, Sr37, Sr39, Sr40, Sr43, Sr47, SrTt3, Sr2S#1 and SrAeg5 to eliminate linkage drag putatively associated with these genes. Additional TTKSK-effective genes Sr44, SrHv6, SrAsp5, and SrAse3 were first targeted for development of compensating translocation stocks and then for shortening the size of each alien segment. Population development is also underway to characterize several potentially new sources of resistance.

Primary Author: Mike Pumphrey, Department of Crop and Soil Sciences, Washington State University, USA

Keywords:

Stocking the Breeder’s Toolbox: An update on the status of resistance to stem rust in wheat

The number of designated stem rust resistance genes has increased by ~10 over the past four years. Translocations involving several broadly-effective alien resistance genes with limited or no previous agricultural deployment were enginneered to reduce the likelihood of linkage drag, and the foundations of adult plant resistance were established. This progress resulted from international collaboration, increased global coordination, and critical financial support. By buidling on these initial accomplishments and improving genetic and genomic resources over the next four years we expect to achieve: 1. more than 10 additional formally designated stem rust resistance genes conferring resistance to Ug99-complex races, 2. robust/diagnostic DNA marker haplotypes identified for most sources of resistance, 3. multiple linkage blocks of two or more resistance genes to enhance gene pyramiding efforts, and 4. knowledge of numerous additional sources of resistance complelely or partially identified. Never before have so many resources and supporting tools been available to combat the wheat rusts. It is an opportune time for the international community to strategically deploy and responsibly steward our genetic resources for durable control of wheat stem rust.

Primary Author: Mike Pumphrey, Department of Crop and Soil Sciences, Washington State University, USA

Keywords:

Pathogenic diversity in Puccinia striiformis f. sp. tritici isolates from Pakistan

225 Puccinia striiformis f.sp. tritici isolates collected from wheat growing areas of Pakistan during 2013-2016 were analyzed using 18 near isogenic yellow rust differentials. Seventy eight races were identified among collection in which 20 were common (n > 2). Rest of the races were very rare and encountered only once (n=1). Races 574212, 574232, 474232, 474233, 574213 and 434232 were most frequent (n> 15). Pathogenic diversity analysis of the collection reveal high diversity (H =3.57) of the P. striiformis population of pakistan. On the basis of phenotypic response to yellow rust genes, the most frequent races could be grouped into 5 diverse groups. Distinct grouping was also observed in rarely encountered isolates. Most of the races were highly complex and 80% isolates had complexity ranging from 8 to 11. Virulence frequency for Yr6, Yr7, Yr8, Yr17, Yr27, Yr43 & YrExp2 remained above 80% while that of Yr1, Yr9 and Yr44 remained over 40%. Partial virulence was detected for Yr5, while virulence to Yr10, Yr15, YrSP was found in < 4% isolates. Paper discuss spatial and temporal distribution of P. striiformis races in Pakistan.

Primary Author: Mirza, Crop Diseases Research Institute, PARC Substation, Murree Pakistan

Keywords:

Wheat rust status and its implications in Pakistan

Detailed rust surveillance of wheat growing areas in Pakistan was conducted from 2011 to 2014. Information about varietal distribution, growth stage, and rust incidence and severity was collected at 950 locations, and rust samples collected from these locations were subjected to race analysis. Yellow rust showed increasing incidence of high to moderate severity. Commercial cultivars released during 1991 to 2011 showed MS to S reactions. Twenty eight races were identified, most with wide virulence ranges. The frequencies of virulence to Yr1, Yr6, Yr7, Yr8, Yr9, Yr17, Yr27, Yr43, Yr44 and YrExp2 all exceeded 50%. Leaf rust also showed increasing incidence, mainly due to cultivation of the susceptible cv. Sehr-06. Fourteen races were identified. The frequencies of virulence to Lr1, Lr2c, Lr3a, Lr16, Lr26, Lr3c, Lr17a, Lr30, LrB, Lr10, Lr14a, Lr14b and Lr21 exceeded 50%. Virulences to Lr2, Lr9, Lr24, Lr18 and Lr19 were not detected and frequencies of virulence to Lr11 and Lr20 were low. Current and old commercial cultivars showed MS to S reactions. In 2011 and 2014 stem rust incidence was sporadic, but in 2013 it was present at 33 of 232 locations in Sindh, Punjab, Khyber Pakhtunkhwa and Baluchistan. Race RRTTF was identified in all samples.

Primary Author: Mirza, Crop Diseases Research Institute, Pakistan Agricultural Research Council, Pakistan

Keywords: Pakistan, surveillance

Marker assisted backcross breeding for incorporation of rust resistance in Indian wheat varieties

Breeding rust resistant cultivars using conventional methods is time-consuming, complex and slow, but molecular markers offer a rapid alternative for developing cultivars with improved disease resistance. Three wheat cultivars, DBW88, DBW107, and DBW110, from different production zones were used as recipients for incorporation of resistance genes using a marker-assisted backcross (MAB) breeding approach. Leaf rust resistance gene Lr32 is being incorporated into all the three varieties, stripe rust resistance gene Yr15 is being incorporated into DBW88 and DBW107, and stem rust resistance gene Sr26 is being added to variety DBW110. Lines PBW703 (Yr15), FLW15 (Lr32) and Avocet (Sr26) were used as donors. Six cross combinations viz., DBW88/PBW703, DBW107/PBW703, DBW88/FLW15, DBW107/FLW15, DBW110/FLW15 and DBW110/Sr26 were made at Karnal during 2015-16 and the crosses were grown at IIWBR-RS, Dalang Maidan for backcrossing. BC1F1 plants were raised at Karnal during 2016-17. Both foreground and background selections were practiced in each combination. SSR markers gwm264 and barc135 were used for foreground selection of Lr32, marker barc8 was used for selection of Yr15, and markers Sr26#43 and BE518379 were used to detect presence and absence of Sr26. From 90 to 127 polymorphic SSR markers chosen for each cross from an initial set of 800 screened on the parents are being used for background selection.

Primary Author: Mishra, ICAR Indian Institute of Wheat and Barley Research, Karnal

Keywords: rusts

Variation in Leaf Tip Necrosis and its effect on yield traits in wheat

Four leaf rust adult plant resistance genes (Lr34, Lr46, Lr67 and Lr68) are known to be associated with leaf tip necrosis (LTN). LTN caused by these genes is different from each other at phenotypic level. LTN associated with APR genes Lr34, Lr46 and Lr67 has been designated as Ltn1, Ltn2 and Ltn3. Seventy-seven CIMMYT genotypes were selected to find out the association between genotypic and phenotypic variability for LTN and its association with yield traits; 1000 grain weight, grain yield, leaf area and percentage of leaf tip necrosis in the flag leaf of main tiller. All the genotypes were screened for the presence of 3 APR genes with linked markers, csLV34 for Lr34; Xwmc44 and Xgwm259 for Lr46 and Xcfd71 for Lr67. The genotypes were grouped into 5 classes; only Lr34, only Lr46, only Lr67, Lr34+L46+Lr67 and genotypes lacking all three genes. Molecular analysis revealed that 7 genotype with Lr34 only, 6 with Lr46 only, 7 with Lr67 only, 13 with all the 3 genes, and 28 without any Lr gene. Phenotypic data of LTN percentage was compared and it was noted that maximum LTN % was observed for Lr67 (7.811%) followed by Lr46 (7.348%) and Lr34 (6.47%). Surprisingly, presence of all three genes reduced the LTN% (4.7055%) as compared with absence of all three genes (6.011%). It was also observed that the three genes simultaneously reduced 1000 grain weight and plot yield. All three genes increased leaf area highly significantly both when they are alone or together (34.7 to 44.7 cm2) in comparison to those genotypes (24.7 cm2) which lacks these Lr genes and also reduced 1000-grain weight and plot yield but non-significantly.

Primary Author: Mishra, Institute of Agricultural Sciences, Banaras Hindu University, India-221005

Keywords: Lr34

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