Posts Tagged ‘Triticum aestivum’

Characterization of dense and erect panicle 1 gene (tadep1) located on common wheat group 5 chromosomes and development of allele-specific markers

Posted by Carelia Juarez on , in Journal Articles

Published in Acta Agronomica Sinica 39 (4) : 589-598, 2013

Liu Ya-Nan, Xia Xian-Chun and He Zhong-Hu

Dense and erect panicle 1 (OsDep1) gene is an important QTL controlling yield associated traits such as panicle length, erect type, and grain density in rice. In the present study, full-length genomic DNA sequences of TaDep1 on common wheat group 5 chromosomes were cloned by homologous cloning approach based on the sequences of rice OsDep1.TaDep1 has five exons and four introns, similar to that of rice OsDep1. The coding sequences of TaDep1-A1TaDep1-B1, and TaDep1-D1 were 918, 888, and 900 bp, encoding polypepetides of 305, 295, and 299 amino acids, respectively. Five allelic variants on TaDep1-A1 locus, four on TaDep1-B1 locus, and two on TaDep1-D1 locus were identified. Three pairs ofcomplementary dominant markers and one codominant marker were developed based on the sequence polymorphisms presented in allelic variants of TaDep1-A1 and TaDep1-B1. The codominant marker dep19, which can accurately discriminate the allelic variants of TaDep1-B1c from those of TaDep1-B1a, TaDep1-B1b,and TaDep1-B1d, was developed from a 30 bp InDel of different allelic variants at the fifth exon of TaDep1-B1. No significant association was found among the yield associated traits such as thousand-kernel weight, plant height, panicle length, spikelet number and spikelet spacing in 406 cultivars, indicating that these genes have no significant effect on the yield-related traits in current Chinese wheat cultivars.

Genetics of resistance to yellow rust in PBW343 × Kenya Kudu recombinant inbred line population and mapping of a new resistance gene YrKK

Posted by Carelia Juarez on , in Journal Articles

Published in Molecular Breeding, 2013

Zaifeng Li, Sukhwinder Singh, Ravi P. Singh, Eric E. López-Vera and  Julio Huerta-Espino

Yellow or stripe rust, caused by Puccinia striiformis f. sp. tritici, is an important disease of common wheat (Triticum aestivum L.) worldwide. A recombinant inbred line (RIL) population, derived from the cross PBW343 × Kenya Kudu, was phenotyped for yellow rust reaction in the field at the CIMMYT research station near Toluca, Mexico, during 2010 and 2011. Segregation results indicated the presence of a race-specific resistance gene, temporarily designated as YrKK, in Kenya Kudu that conferred immunity to adult plants in field trials, despite conferring only slight reductions in seedling reactions in greenhouse tests with three Mexican pathotypes. A minimum of four minor genes having additive effects also segregated in the population and were likely derived from both parents. A total of 635 simple sequence repeat (SSR) primers were screened for polymorphism surveys on the parents, and resistant (YrKK-possessing RILs) and susceptible (YrKK-lacking RILs) bulks identified four polymorphic markers. These markers were located on the short arm of chromosome 2B. Genotypingof the entire RIL population identified Xgwm148 and Xwmc474 as the most closely linked proximal and distal flanking SSR markers, with respective genetic distances of 3.6 and 1.8 cM from YrKK. Four yellow rust resistance genes (Yr27Yr31Yr41, and YrP81) are located on chromosome 2BS; however, their specificity to pathogen pathotypes and host reactions in seedling and adult plants indicate that YrKK is a new resistance gene.

QTL for yield, yield components and canopy temperature depression in wheat under late sown field conditions

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica, 2013

R. Esten Mason, Dirk B. Hays, Suchismita Mondal, Amir M. H. Ibrahim and Bhoja R. Basnet

A wheat (Triticum aestivum L.) recombinant inbred line (RIL) population was used to identify quantitative trait loci (QTL) associated with yield, yield components, and canopy temperaturedepression (CTD) under field conditions. The RIL population, consisting of 118 lines derived from a cross between the stress tolerant cultivar ‘Halberd’ and heat stress sensitive cultivar ‘Karl92’, was grown under optimal and late sown conditions to impose heat stress. Yield and yield components including biomass, spikes m−2, thousand kernel weight, kernel weight and kernel number per spike, as well as single kernel characteristics were determined. In addition, CTD was measured during both moderate (32–33 °C) and extreme heat stress (36–37 °C) during grain-filling. Yield traits showed moderate to high heritability across environments with a large percentage of the variance explained by genetic effects. Composite interval mapping detected 25 stable QTL for the 15 traits measured, with the amount of phenotypic variation explained by individual QTL ranging from 3.5 to 27.1 %. Two QTL for both yield and CTD were co-localized on chromosomes 3BL and 5DL and were independent of phenological QTL. At both loci, the allele from Halberd was associated with both higher yield and a cooler crop canopy. The QTL on 3BL was also pleiotropic for biomass, spikes m−2, and heat susceptibility index. This region as well as other QTL identified in this study may serve as potential targets for fine mapping and marker assisted selection for improving yield potential and stress adaptation of wheat.

Distribucion de fracciones de proteina y su contribucion a las caracteristicas de calidad de trigo

Posted by Carelia Juarez on , in Journal Articles

Published in Revista Fitotecnia Mexicana 36 (2) : 137-145, 2013

Nayelli Hernández Espinosa, Gabriel Posadas Romano, Fausto Cervantes López, Héctor I. González Santoyo, Amalio Santacruz Varela, Ignacio Benítez Riquelme y Roberto J. Peña Bautista

Las características visco-elásticas del gluten del trigo (Triticum aestivum L.) están definidas por la composición de las gliadinas, las  gluteninas de alto (G-APM) y bajo (G-BPM) peso molecular y por la  distribución de sus principales fracciones, la monomérica (rica en  gliadina, PM), la polimérica soluble (rica en glutenina soluble, PPS)  y la polimérica insoluble (rica en glutenina insoluble, PPI). Con el  objetivo de examinar la relación e influencia de estas fracciones sobre las características reológicas de calidad de procesamiento, se evaluaron 117 líneas de trigo procedentes de seis poblaciones contrastantes en calidad, cultivadas bajo riego en Sonora, México (ciclo 2005-2006). La variedad ‘Avocet’ fue el progenitor materno común en cada una de las seis poblaciones. Se consideraron dos variantes en la composición de gluteninas en los loci Glu-A1, Glu-B1, Glu-D1, y tres en el locus Glu-B3.Las medias generales de las proporciones de las tres fracciones fueron de 42 %, 20.4 % y 37.5 % para PM, PPS y PPI, respectivamente. La distribución de fracciones fue distinta entre las seis poblaciones. El análisis estadístico mostró valores de predicción mayores a 30 % de las fracciones proteicas y del contenido de proteína, para estimar variables de calidad del mixógrafo, de fuerza de masa, y de fuerza del gluten medida con el alveógrafo. La magnitud del efecto de las fracciones sobre las características de calidad varió entre las poblaciones de trigo evaluadas. La fracción PM mostró correlaciones significativas con características de extensibilidad de la masa (Sedim-SDS; AlvP/L), mientras que la fracción PPI correlacionó con las variables de fuerza de gluten (MIXTD, %Tq/min y AlvW). La determinación de la distribución de fracciones proteicas, de la composición de G-APM y G-BPM, aunada a pruebas de elaboración rápida en laboratorio (proteína y Sedim-SDS), constituyen una importante herramienta para selección por calidad en el fitomejoramiento del trigo.

Identification and characterization of international Fusarium head blight screening nurseries of wheat at CIMMYT, Mexico

Posted by Carelia Juarez on , in Journal Articles

Published in European Journal of Plant Pathology 136 (1) : 123-134, 2013

Xinyao He, Pawan K. Singh, Etienne Duveiller, Norbert Schlang, Susanne Dreisigacker and Ravi P. Singh

Fusarium head blight (FHB) is a major threat to wheat production globally, causing not only yield losses but also food and feed contamination. FHB research began at the International Maize and Wheat Improvement Center (CIMMYT) in the early 1980’s, and since then, large-scale FHB screening has been conducted to identify and incorporate new resistance genes into elite CIMMYT germplasm. Promising lines with good FHB resistance were regularly compiled as a Fusarium Head Blight Screening Nursery (FHBSN) and distributed worldwide. The first FHBSN was assembled in 1985, and the most recent two were the 13th and 14th FHBSN that were released in 2011 and 2012, respectively. Candidate lines for a FHBSN came mainly from different CIMMYT wheat breeding programs and were tested for three consecutive years before being included in an FHBSN. FHBSN screening was conducted under strictly standardized field conditions at El Batán, where CIMMYT headquarters is located, using artificial inoculation of F. graminearum strains, whose aggressiveness and DON chemotypes had been previously identified. FHB index was scored at 31 days after inoculation for all lines and DON concentration was measured only for elite lines in their 2nd and 3rd year of evaluation. Haplotyping is a new tool for genetic characterization of FHBSN entries and helps to identify new resistance sources with novel resistance genes and to better target crosses toward diversifying and/or pyramiding resistance. The 13th FHBSN was taken as an example in this paper to show the procedure and strategy for the development of new FHB resistant lines.

Contribucion de combinaciones de gluteninas a las caracteristicas del gluten en poblaciones recombinantes de trigo. Contribution of combinations of glutenins to the gluten characteristics of wheat recombinant populations

Posted by Carelia Juarez on , in Journal Articles

Published in Revista Fitotecnia Mexicana 36 (1) : 45-51, 2013

Nayelli Hernández Espinosa, Gabriel Posadas Romano, Fausto Cervantes López, Héctor I. González Santoyo, Amalio Santacruz Varela, Ignacio Benítez Riquelme y Roberto J. Peña Bautista

Las características visco-elásticas del gluten, la fuerza y extensibilidad de las masas de panificación, y consecuentemente la calidad panadera del trigo harinero (Triticum aestivum L.), son mayormente influenciadas por combinaciones de sub-unidades alélicas de gluteninas. Para determinar el efecto de diferentes combinaciones de gluteninas sobre las características visco-elásticas de la masa, se analizaron 201 líneas procedentes de poblaciones recombinantes resultantes de seis cruzamientos entre la variedad ‘Avocet’ como progenitor materno común y las líneas experimentales ‘Attila’, ‘Pastor’, ‘Amadina’, ‘Parula’, ‘Tonichi’ y ‘Pavón’. El material genético fue cultivado bajo riego en Cd. Obregón, Sonora, México. Se analizó la composición de gluteninas de alto (G-APM) y bajo (G-BPM) peso molecular y se estimó el efecto de cada variante alélica de los loci Glu-A1, Glu-B1 y Glu-D1 y de sus combinaciones alélicas, sobre las características reológicas de la masa medidas con mixógrafo y alveógrafo. Dentro del locus Glu-A1 la presencia del alelo 1 se relacionó con mayor fuerza de gluten; en Glu-B1 los alelos 7+8 y 17+18 produjeron efectos similares en las variables de calidad, y en el locus Glu-D1 el alelo 5+10 indujo mayor fuerza y extensibilidad. En las seis poblaciones se encontraron 12 combinaciones alélicas de gluteninas entre los loci Glu-A1, Glu-B1 y Glu-D1. Las combinaciones alélicas 2*, 17+18, 2+12; 2*, 7+8, 2+12; y 2*, 17+18, 5+10  mostraron la mayor influencia positiva sobre las características asociadas con fuerza y extensibilidad de masa, en comparación con el resto de combinaciones.



QTL Mapping for Adult-Plant Resistance to Stripe Rust in a Common Wheat RIL Population Derived from Chuanmai 32/Chuanyu 12

Posted by Carelia Juarez on , in Journal Articles

Published in Journal of Integrative Agriculture 11 (11) : 1775-1782, 2012

Wu Ling, Xia Xian-Chun, Zheng You-liang, Zhang Zheng-yu, Zhu Hua-zhong, Liu Yong-jian, Yang En-nian, Li Shi-zhao and He Zhonghu

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a devastating wheat disease worldwide. The Chinese wheat cultivar Chuanmai 32 has shown stable resistance to stripe rust for 10 yr in Sichuan Province, a hotspot for stripe rust epidemics. The objective of the present study was to map quantitative trait loci (QTL) for adult-plant resistance (APR) to stripe rust in a population of 140 recombinant inbred lines (RILs) derived from Chuanmai 32/Chuanyu 12. Field trials were conducted in Chengdu and Yaan, Sichuan, from 2005 to 2008, providing stripe rust reaction data for 6 environments. 797 simple sequence repeat (SSR) markers were screened for association with stripe rust reaction, initially through bulked segregant analysis (BSA). Based on the mean disease values averaged across environments, the broad-sense heritability of maximum disease severity (MDS) was 0.75. Two QTLs for stripe rust resistance were detected by composite interval mapping (CIM). They were designated QYr.caas-3BL and QYr.caas-3BS and explained from 6.6 to 20.1%, respectively, of the phenotypic variance across environments. QYr.caas-3BL came from Chuanmai 32; QYr.caas-3BS with lower effect was from the susceptible parent Chuanyu 12. Both QTLs appear to be new.

Mapping of Quantitative Trait Loci for Adult Plant Resistance to Stripe Rust in German Wheat Cultivar Ibis

Posted by Carelia Juarez on , in Journal Articles

Published in Journal of Integrative Agriculture 11 (4) : 528-536, 2012

Bin Bai,  Yan Ren, Xian-chun Xia,  Jiu-yuan Du,  Gang Zhou,  Ling Wu,  Hua-zhong Zhu,  He Zhonghu and  Cheng-she Wang

The German wheat cultivar Ibis has excellent adult plant resistance (APR) to stripe rust in Gansu, a hotspot for stripe rust in China. To elucidate the genetic basis of APR to stripe rust in Ibis, 237 F3 lines derived from the cross Ibis/Huixianhong were evaluated at Tianshui, Gansu, in the 2008–2009 and 2009–2010 cropping seasons, and at Chengdu, Sichuan Province, China, in the 2009–2010 cropping season. Inoculations were conducted with a mixture of several prevalent Pst races in both locations. Maximum disease severity (MDS) data showed a continuous distribution of response, indicating quantitative nature of resistance to stripe rust in Ibis. The broad-sense heritability of MDS was 0.75 based on the mean values averaged across three environments. A total of 723 simple sequence repeat (SSR) markers were used to map the QTL for APR by inclusive composite interval mapping (ICIM). QTLs mapping to chromosomes 2BS and 6BS, designated as QYr.caas-2BS.1 and QYr.caas-6BS.1, respectively, explained 4.1–40.7% of the phenotypic variance in MDS across environments. The major effect QTL QYr.caas-2BS.1, flanked by Xgwm148 and Xwmc360, was consistently detected at all three sites as well as the averaged data over three environments, accounting for 40.7, 24.2, 5.2 and 29.9% of phenotypic variance, respectively. The molecular markers closely linked to this QTL have potential for use in marker-assisted selection and gene pyramiding to improve the durability of stripe rust resistance in wheat breeding.

Pyramiding adult-plant powdery mildew resistance QTLs in bread wheat

Posted by Carelia Juarez on , in Journal Articles

Published in Crop and Pasture Science 63 (7) : 606-611, 2012

B. Bai, Z. H. He, M. A. Asad , C. X. Lan, Y. Zhang, X. C. Xia, J. Yan, X. M. Chen and C. S. Wang

Pyramiding of quantitative trait loci (QTLs) can be an effective approach for developing durable resistance to powdery mildew in wheat (Triticum aestivum L.). The Chinese wheat cultivars Bainong 64 and Lumai 21, with outstanding agronomic traits, possess four and three QTLs, respectively, for adult-plant resistance (APR) to powdery mildew. To achieve optimal durable resistance, 21 F6 lines combining two–five powdery mildew APR QTLs were developed from the cross Bainong 64/Lumai 21 using a modified pedigree selection. These lines were planted in a randomised complete block design with two replicates in Beijing during the 2009–10 and 2010–11 cropping seasons, and were evaluated for powdery mildew response using the highly virulent Blumeria graminis f. sp. tritici isolate E20. Based on the phenotypic data of both maximum disease severity (MDS) and area under the disease progress curve (AUDPC), analysis of variance indicated that there were highly significant effects of QTL combinations on reducing powdery mildew MDS and AUDPC. Six pyramided QTL combinations possessing QPm.caas1A and QPm.caas4DL in common along with one or more of the others expressed better APR to powdery mildew than the more resistant parent, Bainong 64. Thus, pyramiding these two QTLs with one or more of QPm.caas2BS, QPm.caas2BL, and QPm.caas2DL from Lumai 21 could be a desirable strategy to breed cultivars with high levels of durable resistance to powdery mildew. Experienced breeders with a good knowledge of minor genes can achieve APR by phenotypic selection, and selection by molecular markers will still require uniform field testing for powdery mildew and disease phenotype to validate the resistance. These results provided very useful information for pyramiding APR QTLs in wheat breeding programs.

Performance of biofortified spring wheat genotypes in target environments for grain zinc and iron concentrations

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research 137 : 261-267, 2012

G. Velu, R.P. Singh, J. Huerta-Espino, R.J. Peña, B. Arun, A. Mahendru-Singh, M. Yaqub Mujahid, V.S. Sohu, G.S. Mavi, J. Crossa, G. Alvarado, A.K. Joshi and W.H. Pfeiffer

Genetic biofortification to improve zinc (Zn) and iron (Fe) concentrations in bread wheat (Triticum aestivum L.) could reduce micronutrient malnutrition-related problems in the developing world. A breeding program on wheat was started to enhance Zn and Fe concentrations and other essential traits needed in a successful commercial variety. The first set of advanced lines derived from crosses of high yielding wheats with genetic resources possessing high Zn and Fe such as Triticum spelta, landraces and synthetic wheat based on Triticum dicoccon were tested at nine locations in South Asia and Mexico for Zn and Fe concentration, grain yield and other traits. Analyses of variance across locations revealed significant genotypic, environmental and genotype × environment (G × E) effects for grain Zn and Fe concentrations and grain yield. Variances associated with environmental effects were larger than the genotypic and G × E effects for all three traits, suggesting that environmental effects have relatively greater influence. Although G × E interaction was significant, high heritabilities were observed for Zn and Fe concentrations at individual sites and across environments, reflecting non-crossover type of interaction. This trend was confirmed by the high genetic correlations between locations that showed similar ranking of entries across locations, indicating that it is possible to select the best adapted entries with high Zn and Fe concentration. Pooled data across locations showed increments of 28% and 25% over the checks for Zn and Fe. A considerable number of entries exceeded intermediate to full breeding target Zn concentrations, indicating that it is possible to develop Zn-biofortified varieties with competitive yields and other farmer preferred agronomic traits. The positive and moderately high correlation between Zn and Fe concentration suggest good prospects of simultaneous improvement for both micronutrients.