Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Effect of Ug99 Race of Stem Rust (Puccinia Graminis F.Sp. Tritici) on Growth and Yield of Barley (Hordeum Vulgare L.) in Kenya  [cached]
Edward K. Mwando,Isaiah M. Tabu,Daniel O. Otaye,Peter N. Njau
Journal of Agricultural Science , 2012, DOI: 10.5539/jas.v4n5p161
Abstract: Barley stem rust caused by Puccinia graminis f.sp. tritici Eriks. & E. Henn, was previously contained through the use of genetic resistance resulting from genes such as rpg1 but, in 1999 and 2001 a new race Ug99 or TTKSK with virulence to stem rust resistant cultivars carrying resistance gene rpg1, was detected in Uganda and Kenya, respectively. The new variants of Ug99 like PTKST, TTKSF, TTKST and TTTSK with virulence to genes Sr21, Sr24, and Sr36 of wheat have been detected implying that the race Ug99 is evolving. The experiment was carried out at the Kenya Agricultural Research Institute (KARI) Njoro for two seasons (2008 and 2009) to find out the effect of the new race of Ug99 on the growth and yield of barley. The genotypes included three Kenyan commercial cultivars (Nguzo, Sabini and Karne), two (1512-5 and 1385-13) new introductions from the Kenya malting company and 15 introductions from ICARDA selection. The genotypes were screened for their level of resistance to stem rust disease in the field where each cultivar was sown in plots of 3m length at spacing of 20 cm, at seed rate of 125 kg ha-1 . The same set was sown as control under fungicides application of tebuconazole (folicur) at 0.75 L ha-1 , 3 times in the season starting at stem elongation stage (Zadoks et al., 1974) at an interval of 21 days. The experimental design was randomized complete block design (RCBD) in split plot arrangement with the main plots as the 20 barley cultivars, while the subplots consisted of fungicide (protected and unprotected), replicated three times. Susceptible wheat cultivars, Chozi was planted perpendicular to test plots in the middle of the 1-m pathways on both sides of experimental plots to serve as spreader. Genotype 1512-5 showed the highest severity of (93%) in season 1, while Sabini had the highest severity of 30% in the second season. Nguzo had the lowest disease severity of 16% and 5% in season 1 and 2, respectively. The highest dry matter loss of 41.1 and 43.1% was observed in ICARDA-07 and ICARDA-09 in season 1 and 2, respectively. The highest and lowest loss of 67.3% and 17.8% in leaf area was recorded on Sabini and 1385-13 in season 1 respectively. Irrespective of season, higher chlorophyll index was noted in treated plots than in untreated ones. Genotypes ICARDA-14 and ICARDA-13 had the highest (45.8%) and lowest (8.7%) reduction in number of effective tillers in season 1. The new race Ug99 (TTKS) of stem rust caused severe loss on the susceptible genotypes. The highest yield loss of 53.8% was observed in ICARDA-08 while the lowest loss of 6.9% w
Agronomic Factors on Selected Hulless Barley Genotypes  [PDF]
Hamid Reza Balouchi,Zeinalabedin Tahmasbi Sarvestani,Seyed Ali Mohammad Modarres Sanavy
Journal of Agronomy , 2005,
Abstract: Yield and yield components evaluation of different hulless barley (Hordeum vulgare L.) genotypes with objective determination of the best plant density and nitrogen fertilizer rate is necessary for obtaining maximum quality and quantity yield. In the first year, for these propose twenty genotypes were evaluated in aspect of quality and quantity yield. In second experiment, ten best genotypes selected from the first experiment were evaluated for agronomic factors such as plant density and N fertilizer rate application. Both experiments were conducted in Research Farm of Tarbiat Modarres University, College of Agriculture, Tehran, Iran during 2001-2003 growing season. The experimental designs of first and second experiments were Randomized Complete Block and Split-Split-Plot laid out in Randomized Complete Block designs, respectively, with three replications and a total of ten genotypes (as main plot), 2 levels of nitrogen fertilizer (90 and 120 kg nitrogen ha-1 as subplot) and 3 plant densities (300, 400 and 500 plants m-2 as sub sub-plot). The results showed that a significant difference between genotypes and plant density interaction in grain yield and harvest index. The highest grain yield, spike number m-2 and grain number spike-1 were produced by ALLSO`S`/C103902-2 genotype under 500 plant m-2. FICC2595 Genotype showed the highest thousand-kernel weight (46 g) and FICC1570 genotype produced the highest spike number m-2 (958 spike m-2). The mean comparison of protein yield in different plant density m-2 showed that 500 plants m-2 treatment produced the highest protein yield (58.48 g m-2).
Quantitative and Qualitative Stem Rust Resistance Factors in Barley Are Associated with Transcriptional Suppression of Defense Regulons  [PDF]
Matthew J. Moscou,Nick Lauter ,Brian Steffenson,Roger P. Wise
PLOS Genetics , 2011, DOI: 10.1371/journal.pgen.1002208
Abstract: Stem rust (Puccinia graminis f. sp. tritici; Pgt) is a devastating fungal disease of wheat and barley. Pgt race TTKSK (isolate Ug99) is a serious threat to these Triticeae grain crops because resistance is rare. In barley, the complex Rpg-TTKSK locus on chromosome 5H is presently the only known source of qualitative resistance to this aggressive Pgt race. Segregation for resistance observed on seedlings of the Q21861 × SM89010 (QSM) doubled-haploid (DH) population was found to be predominantly qualitative, with little of the remaining variance explained by loci other than Rpg-TTKSK. In contrast, analysis of adult QSM DH plants infected by field inoculum of Pgt race TTKSK in Njoro, Kenya, revealed several additional quantitative trait loci that contribute to resistance. To molecularly characterize these loci, Barley1 GeneChips were used to measure the expression of 22,792 genes in the QSM population after inoculation with Pgt race TTKSK or mock-inoculation. Comparison of expression Quantitative Trait Loci (eQTL) between treatments revealed an inoculation-dependent expression polymorphism implicating Actin depolymerizing factor3 (within the Rpg-TTKSK locus) as a candidate susceptibility gene. In parallel, we identified a chromosome 2H trans-eQTL hotspot that co-segregates with an enhancer of Rpg-TTKSK-mediated, adult plant resistance discovered through the Njoro field trials. Our genome-wide eQTL studies demonstrate that transcript accumulation of 25% of barley genes is altered following challenge by Pgt race TTKSK, but that few of these genes are regulated by the qualitative Rpg-TTKSK on chromosome 5H. It is instead the chromosome 2H trans-eQTL hotspot that orchestrates the largest inoculation-specific responses, where enhanced resistance is associated with transcriptional suppression of hundreds of genes scattered throughout the genome. Hence, the present study associates the early suppression of genes expressed in this host–pathogen interaction with enhancement of R-gene mediated resistance.
Postulation of genes for stem rust resistance in selected wheat lines from Nepal  [cached]
Indian Phytopathology , 2012,
Abstract: Fifty five wheat lines / cultivars were seedling evaluated against eight pathotypes of stem rust (Pueeinia graminis f. sp. tritiei). Seven 5r genes (5r2, 5r5, 5r7b, 5rBa, 5r9b, 5r11 and 5(31) were characterized in fifty one lines/ cultivars singly or in combination with each other. Resistance to stem rust in 24 lines was largely dependent on 5r31 followed by 5r2, 5r11, 5r9b, 5rBa, 5r5 and 5r7b either singly or in combina
Effect of host genotypes and specific pathotypes of stem rust on Sr-gene expression in five bread wheats  [cached]
Indian Phytopathology , 2012,
Abstract: Expression pattern of Sr-genes in five bread wheat cultivars viz., HD 2135, HD 2160, HD 2189, HD 2285 and Vaishali to different stem rust pathotypes 21(9G5), 40-1(62G29-1) and 117A(36G2) and host genetic background was studied. In cvs. HD 2135, HD 2160 and HD 2285, the gene Sr30 expressed in a recessive manner to pathotype 40- 1(62G29-1), but did not express to pathotypes 21(9G5) and 117A(36G2) at temperature 19-28°C. This may be due to complex interaction between host genotype and pathotype. In Agra Local (AL) background, genes Sr5, Sr7b, Sr8a, Sr9b, SrlO and Srll expressed in a dominant manner, while Sr30 expressed in a recessive manner to above 3 pathotypes.
Characterization of soybean genotypes for Asian soybean rust reaction
Araujo, Milena Moura de;Vello, Natal Antonio;
Crop Breeding and Applied Biotechnology , 2010, DOI: 10.1590/S1984-70332010000300003
Abstract: our objective was to characterize soybean experimental lines for asian soybean rust reaction. in the 2004/2005 growing season, three experiments were conducted with middle-cycle and three with late-cycle genotypes, designed in randomized blocks with four replications. twelve experimental lines and two cultivars of each cycle were used. in each experiment the plant management differs as follows: three applications of carbendazim or three of flutriafol or without applications. the experimental lines with high yield, low notes to the symptoms and resistance to lodging, were selected and tested again in the 2005/2006 growing season. genotypes with high severity and yield were considered tolerant to rust and the low severity and high yield ones as moderately resistant. among the medium-cycle genotypes, there was moderate resistance to rust in one line and tolerance in five. among the late-cycle genotypes, the six lines showed moderate resistance. the line usp 97-08135 is more tolerant to rust.
Screening Wheat and Barley Genotypes for Salinity Resistance  [PDF]
Talal Thalji,Ghalib Shalaldeh
Journal of Agronomy , 2007,
Abstract: To screen wheat and barley genotypes for salinity resistant, 10 bread wheat, 12 durum wheat and 11 barley genotypes were planted under saline conditions. Salinity was ranged (20.6-21.9 and 4.5-5.5 dS m-1) for both soil and water, respectively. Wheat genotypes Jumaizah, Bin-bashair and Snap and barley genotypes Acsad 176, line 5 and Rum showed high biological yield Performance. Genotypes: Jumaizah, Bin-bashair, Snap, Cham3 and Cham6 and barley genotypes: line3, line2 and line5 showed high seed yield performance. However wheat genotypes Behowth1 exhibited the highest straw yield performance compared to other wheat genotypes. Germination percentage has a strong positive correlation with seed yield (0.75) and straw yield (0.41). Negative association between heading and physiological maturity periods with seed yield (-0.29) for each was obtained. Concerning wheat and barley genotypes nitrogen (N) content at the three leaf stage was negatively correlated (-0.19) with seed yield compared to the elongation stage, while, Potassium (K) and K/Na ratio showed a strong positive correlation at the tree leaf stage (0.21 and 0.22), respectively. In wheat genotypes Potassium (K) content, (K/Na) and Sodium (Na) have showed a strong positive correlation with seed yield in wheat genotypes (0.26, 0.29 and 0.30), respectively whereas, chloride (CL) showed a strong negative correlation (-0.26) with the seed yield. In barley genotypes, P and K have a strong negative correlation with the biological yield (-0.42 and -0.39), respectively and with the straw yield (-0.47 and -0.49), respectively at the three leaf stage. Sodium (Na) (-0.39) has the same trend like P and K but at the elongation stage. It is clear that leaf analysis at the 3-leaf stage is more indicative to reveal salinity resistance in both wheat and barley genotypes compared to the advanced growth stages. K/Na ratio could be used as selection criteria for salinity resistance because it is highly correlated with biological, seed and straw yields in both wheat and barley genotypes. Bread wheat genotypes: Jumaizah and Cham6, durum wheat genotypes: Bin-bashair, Cham3 and Snap and barley genotypes: Line5, Accsad176 and Rum are selected as salinity resistant genotypes.
Selección de genotipos de avena para la identificación de razas de roya del tallo Selection of oat genotypes for the identification of stem rust races  [cached]
Luis Antonio Mariscal Amaro,Julio Huerta Espino,Héctor Eduardo Villase?or Mir,Santos Gerardo Leyva Mir
Revista mexicana de ciencias agrícolas , 2011,
Abstract: La identificación de razas fisiológicas de Puccinia graminis f. sp. avenae al usar diferenciales, es importante en los programas de mejoramiento genético de avena, para obtener genotipos resistentes a roya del tallo y conocer la evolución y dispersión regional del patógeno. En 2008-2009 en los invernaderos del CIMMYT, El Batán, México, se probaron 50 aislamientos monopustulares de P. graminis f. sp. avenae en 24 genotipos de avena (Avena sativa L.), con el objetivo de determinar la diversidad del patógeno en muestras recolectadas en seis estados de México y conocer si estos genotipos podían ser utilizados como plantas diferenciales. Los genotipos Avemex, Obsidiana, Papigochi, Diamante, Rarámuri, Chihuahua y el Progenitor 7, expresaron diferentes tipos de infección y se pueden usar como diferenciales para estudiar la diversidad del patógeno y la prevalencia de razas. Al usar estas diferenciales se encontraron 24 razas diferentes del patógeno. Esto permite concluir que existe gran variabilidad genética del hongo en las regiones muestreadas. Se observó que ante los aislamientos probados las variedades Agata, Avena desnuda, Menonita y Saia, mostraron el mayor nivel de resistencia; y los progenitores 11, 12 y 13, y las variedades 12, 14, 27, 28, 36, 43 y 44 tuvieron buen nivel de resistencia, por lo que pueden ser utilizados como progenitores en futuros planes de cruzamientos. Identification of physiological races of Puccinia graminis f. sp. avenae using differentials, is important in oat's genetic improvement programs, in order to obtain resistance to stem rust and learn about evolution and regional spread of the pathogen. In 2008-2009, in greenhouses of CIMMYT, El Batan, Mexico, 50 monopustule isolates of P. graminis f. sp. avenae were tested in 24 genotypes of oat (Avena sativa L.), in order to determine the pathogen diversity in samples collected in six states of Mexico and see if these genotypes could be used as differential plants. Genotypes Avemex, Obsidiana, Papigochi, Diamante, Raramuri, Chihuahua and Progenitor 7, expressed different types of infection and can be used as differentials to study pathogen diversity and races prevalence. Using these differentials, 24 different races of the pathogen were found. This leads to the conclusion that there is great genetic variability of the fungus in the sampled regions. Against isolates tested, it was noted that Agata, Avena desnuda, Menonita and Saia varieties, showed the highest resistance level and progenitors 11, 12 and 13 and varieties 12, 14, 27, 28, 36, 43 and 44 had good resistance level, so they ca
Prueba de similitud en genes con resistencia a roya del tallo en genotipos de avena Test of similarity in genes with resistance to stem rust in oat genotypes  [cached]
Luis Antonio Mariscal Amaro,Julio Huerta Espino,Héctor Eduardo Villase?or Mir,Santos Gerardo Leyva Mir
Revista mexicana de ciencias agrícolas , 2010,
Abstract: La roya del tallo causada por Puccinia graminis Pers. f. sp. Avenae, es considerada el factor biótico que más afecta al cultivo de avena (Avena sativa L.), disminuyendo el rendimiento y peso de grano en variedades susceptibles, en 75% y 60%, respectivamente. La estrategia que más ha apoyado al control de esta enfermedad es el uso de variedades resistentes, requiriéndose constantemente de fuentes de resistencia. La forma cómo opera la resistencia y los genes que están confiriéndola en el germoplasma de avena se desconoce; de tal modo, que es necesario hacer más estudios sobre número y similitud de genes así como de su forma de acción. El objetivo del estudio fue determinar la similitud y el número de genes de resistencia en planta adulta y plántula, en familias F3 de cruzas entre seis progenitores de avena, moderadamente resistentes a roya del tallo; por su importancia para los programas de mejoramiento como fuentes de resistencia, mediante el análisis de las progenies derivadas de las cruzas entre ellos desde 2006 a 2009. En estado de plántula en invernadero, los progenitores por separado tuvieron lecturas de 0, ";", y 1, indicando su resistencia ante el aislamiento PgaMex99.13. Las familias F3 de todas las cruzas no segregaron familias susceptibles, indicando que estos seis progenitores poseen un gen en común confiriendo resistencia contra el aislamiento probado. En campo, aún con inoculaciones del mismo aislamiento, las familias en todas las cruzas mostraron diferentes niveles de infección, algunos mayores a 60% indicando la incidencia de otras razas distintas a la inoculada, para las cuales el gen de resistencia en común en los progenitores no fue efectivo. The stem rust caused by Puccinia graminis Pers. f. sp. Avenae is considered the biotic factor that affects the most to oat cultivation (Avena sativa L.), decreasing yield and grain weight in susceptible varieties, in 75% and 60%, respectively. The strategy that has supported control of this disease is the use of resistant varieties, constantly requiring of resistance sources. The way resistance works, and the genes that give it to oat germoplasm, is still unknown; then is necessary to make more studies about number and similarity of genes as well as in their activity. The aim of the study was to determine similarity and number of resistance genes in mature plant and seedlings, in families F3 of crosses between oat parents, moderately resistant to stem rust; due their importance for the programs of improvement as resistance sources, by means of analysis of the derived progenies of cross between the
Sources of stem rust resistance in Ethiopian tetraploid wheat accessions
N Beteselassie, C Fininsa, A Badebo
African Crop Science Journal , 2007,
Abstract: Stem or black rust of wheat caused by the fungus Puccinia graminis f. sp. tritici Ericks and Henn (Pgt) is an important disease on wheat worldwide. Pgt is an obligate biotroph, heteroceous in its life cycle and heterothallic in mating type. Seedlings of 41 emmer (Triticum dicoccum), 56 durum (T. durum) wheat accessions were tested for their response to stem rust (Puccinia graminis f. sp. trictici) infection under greenhouse condition at Kulumsa Agricultural Research Center, Ethiopia. The test included screening of accessions and multipatotype testing to postulate sr genes. Vigorous screening of accessions was conducted using ten stem rust races, namely TKM/J, SKM/J, TTM/J, STM/J, TTL/K, TKR/J, TKM/J, TTM/H, SKM/J and JKM/G and, 33 stem rust differential lines. Flor’s gene-for-gene theory was applied to postulate Sr genes in the tested accessions. Eighteen emmer and 6 durum accessions were found to be good sources of resistance to stem rust infection. In addition, the presence of Sr 7b, 8b, 9a, 9b, 10, 14, 24, 27, 28, 29, 30, 31, 32 and Tt-3 + 10 genes was postulated in 16 selected emmer and 5 durum wheat accessions. Hence, efforts to exploit these valuable Sr genes in Ethiopian cultivated tetraploid wheats could be rewarding to get stem rust resistant varieties and boost wheat production.
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.