Posts Tagged ‘Triticum aestivum’

Association of staygreen trait with canopy temperature depression and yield traits under terminal heat stress in wheat (Triticum aestivum L.)

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica, 2012

Maya Kumari, R. N. Pudake, V. P. Singh and Arun K. Joshi

The presence or absence of the staygreen trait was screened for 3 consecutive years in 963 wheat lines from various sources, including Indian and CIMMYT germplasm. Staygreen was assessed at the late dough stage by visual scoring (0–9 scale) and the leaf area under greenness (LAUG) measurement. Around 5.5 % of the lines were staygreen, 10.5 % were moderately staygreen, and the remaining lines showed little or no expression of the trait. One hundred lines showing diversity for the staygreen trait were sown under three different sowing dates (timely, late and very late) for 3 consecutive years in three replications to determine the association of staygreen with heat tolerance. There was a decline in yield, biomass, grain filling duration (GFD) and 1,000 grain weight (TGW) under late and very late sowing conditions owing to terminal stress at anthesis and later stages. However, the decline was relatively less in staygreen genotypes compared to the non-staygreen (NSG) ones. The correlation study showed that LAUG and canopy temperature depression (CTD) were strongly correlated. LAUG and CTD were also significantly associated with grain yield, GFD and biomass. To further confirm the association of the staygreen trait with terminal heat stress, individual F2-derived F7 progenies from the cross of the ‘staygreen’ lines with NSG were evaluated for yield and yield traits at the three sowing dates. In each cross, the staygreen progenies showed a significantly smaller decline in yield and TGW under heat stress than the NSG progenies. These results appear to suggest an association between the staygreen trait and terminal heat stress and, thereby, that the staygreen trait could be used as a morphological marker in wheat to screen for heat tolerance.

Identification of QTL associated with durable adult plant resistance to stem rust race Ug99 in wheat cultivar ‘Pavon 76’

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica, 2012

P. N. Njau, S. Bhavani, J. Huerta-Espino, B. Keller and R. P. Singh

Stem rust of wheat, caused by Puccinia graminis f. sp. tritici, was under control worldwide for over 30 years by utilizing genetic resistance. The emergence of stem rust in 1998 in eastern Africa in form of race Ug99 and its evolving variants with virulence to many resistance genes were recognized as potential threats to wheat production. In this study we identified genomic regions contributing to putatively durable, adult plant resistance (APR) to wheat stem rust. A recombinant inbred line (RIL) population of 298 lines was previously developed at CIMMYT from a cross between ‘Avocet S’ and ‘Pavon 76’. Pavon 76 has been described to carry APR to stem rust. Avocet S carries the race-specific resistance gene Sr26. A subset of RILs without Sr26 segregated for APR to stem rust race Ug99 when evaluated in Kenya for three years. Single year and joint year analysis by inclusive composite interval mapping using 450 DArT markers identified five quantitative trait loci (QTL) that contributed to the resistance of wheat to stem rust race Ug99. Three of these, including QSr.cim-3B, which probably represents the Sr2 gene, were contributed by Pavon 76 whereas the remaining two QTL were contributed by Avocet S. QSr.cim-3B, or putatively Sr2, on chromosome arm 3BS explained 32 % of the phenotypic variation while the additional QTL in Pavon contributed 24 and 20 %, respectively. Two QTL from Avocet S explained 8 and 6 % of phenotypic variance, respectively. A combination of APR QTL from the two parents resulted in transgressive segregants expressing higher levels of resistance than Pavon 76. Our results indicate that it is possible to accumulate several minor resistance genes each with a small to intermediate effect resulting in a variety that exhibits negligible disease levels even under high stem rust pressure.

 

Exploring the possibility of obtaining terminal heat tolerance in a doubled haploid population of spring wheat (Triticum aestivum L.) in the eastern Gangetic plains of India

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research 135: 1-9, 2012

Chhavi Tiwari, Hugh Wallwork, Ram Dhari, B. Arun, V.K. Mishra and Arun K. Joshi

High temperature during grain filling stage causes significant yield losses to wheat in south Asia and many other parts of the world. One hundred and forty doubled haploid (DH) wheat lines (including parents), derived from the cross Berkut (heat susceptible) × Krichauff (heat tolerant), were grown in six environments comprising two dates of sowing in three consecutive years (2007–2008, 2008–2009, and 2009–2010) at Banaras Hindu University, Varanasi, India. The objective was to assess DH lines for heat tolerance and to identify superior lines under hot humid environments of the eastern Gangetic plains (EGP) of India. Considerable variation was observed for grain yield (GY), thousand grain weight (TGW), grain fill duration (GFD), and canopy temperature (CT). Likewise, considerable variation was also observed for heat susceptibility index (HSI) of GY, TGW, and GFD. The DH lines were grouped into four categories based on the HSI and around 5–10% lines were categorized as heat tolerant. A few lines yielded significantly more than the better parent and possessed good expression of other traits. The most promising 20 lines have been listed as sources of heat tolerance, with 3 lines better yielding than the superior parent Krichauff. The results demonstrated that it is possible to obtain lines that perform better for yield and yield related traits in heat stressed environments of the EGP of India.

Contribución de los loci Glu-B1, Glu-D1 y Glu-B3 a la calidad de la masa del trigo harinero

Posted by Carelia Juarez on , in Journal Articles

Published in Revista Fitotecnia Mexicana  35 (2): 135-142, 2012

Eliel Martínez Cruz, Eduardo Espitia Rangel, Héctor E. Villaseñor Mir y Roberto J. Peña Bautista

En esta investigación, se identificaron combinaciones y variantes alélicas de gluteninas de alto y bajo peso molecular (GAPM y GBPM), y se evaluó su efecto en las características reológicas de la masa de trigos harineros (Triticum aestivum L.). Se usaron los progenitores ?Bacanora T88? y ?Salamanca S75? y como progenie derivada de su cruza consistente en 98 líneas recombinantes obtenidas por descendencia de una sola semilla de F2 a F6. Los 100 genotipos fueron sembrados en Celaya, Guanajuato, México, durante el ciclo primavera-verano 2008. Las variables evaluadas fueron: tiempo de amasado, estabilidad al amasado, tolerancia al sobreamasado, fuerza general de la masa y la relación tenacidad/extensibilidad. Se identificaron las GAPM y GBPM en geles de poliacrilamida en presencia de dodecil sulfato de sodio. Se encontró que los loci Glu-B1, Glu-D1 y Glu-B3 afectaron las propiedades de fuerza y extensibilidad de la masa. La combinación de los alelos 2*, 7+9, 5+10, c, g, b presentó gluten fuerte y excelente extensibilidad apto para la panificación, mientras que la combinación alélica 2*, 7+9, 2+12, c, g, b condicionó gluten débil y extensible útil en la fabricación de galletas y tortillas. Las combinaciones 2*, 7+9, 2+12 c, j, b y 2*, 7+8, 2+12 c, j, b se asociaron con menor fuerza y mayor extensibilidad de la masa, respectivamente. Las variantes alélicas de GAPM 7+8, 7+9 y 5+10 de los loci Glu-B1 y Glu-D1 se clasificaron como de gluten fuerte; mientras que 2+12 se asoció con gluten medio fuerte. El alelo j de GBPM del locus Glu-B3 presentó los valores más altos para la relación tenacidad/extensibilidad y los menores para fuerza, contrario a la variante g. Lo anterior muestra que mediante la selección de progenitores y la recombinación de sus alelos se pueden obtener genotipos de trigo harinero con calidad específica de la masa.

 

QTL mapping of adult-plant resistance to stripe rust in Chinese wheat cultivar Chuanyu 16

Posted by Carelia Juarez on , in Journal Articles

Published in Journal of Agricultural Science 4 (3): 57-70, 2012

Ling Wu, Youliang Zheng, Xianchun Xia, Yunliang Peng, Huazhong Zhu, Yongjian Liu, Yu Wu, Shizhao Li, Zhonghu He

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is a serious wheat fungal disease, causing significant annual yield losses worldwide. The Chinese wheat cultivar Chuanyu 16 has shown good adult-plant resistance (APR) to stripe rust in Sichuan province, a hotspot for stripe rust epidemics. Chuanyu 16 was crossed with Chuanyu 12 and Chuanmai 32. Two populations, each with 140 recombinant inbred lines (RILs), were developed by single-seed descent, and used for quantitative trait locus (QTL) mapping. Field trials were conducted in Chengdu and Yaan from 2005 to 2008, providing stripe rust reaction data for six environments. Seven hundred and thirty one simple sequence repeat (SSR) markers were screened for association with stripe rust reaction, initially through bulked segregant analysis (BSA). Three QTLs for stripe rust resistance derived from Chuanyu 16 were detected in the first cross. They were detected by inclusive composite interval mapping (ICIM) and designated QYr.caas-1BL.1, QYr.caas-1BL.2 and QYr.caas-2AS. They explained 6.0 – 12.8%, 4.5 – 5.8% and 14.9 – 43.0%, respectively, of the phenotypic variance across environments. One digenic epistatic QTL between QYr.caas-1BL.2 and QYr.caas-2AS explained 4.3 – 10.4% of the phenotypic variance. QYr.caas-2AS was also detected in Chuanmai 32/Chuanyu 16, explaining 27.9 – 57.2% of the phenotypic variance across six environments. This QTL showed a major effect against stripe rust in Chuanyu 16, and was located in a similar position to Yr17. Specific markers indicated the presence of a segment from chromosome 2N of Triticum ventricosum that carries Yr17. Despite the lack of evidence for Yr17 in Chuanyu 16 based on pedigree, and inconsistencies in stripe rust response relative to a near-isogenic reference stock with the gene, we concluded that QYr.caas-2AS is Yr17. QYr.caas-1BL.1 and QYr.caas-1BL.2 showed minor effects for APR against stripe rust. QYr.caas-1BL.1 is probably a new gene for APR to stripe rust.

Genomic characterization of drought tolerance-related traits in spring wheat

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica 186 (1): 265-276, 2012

Sundeep Kumar, Sunish Kumar Sehgal, Uttam Kumar, P. V. Vara Prasad, Arun Kumar Joshi and Bikram Singh Gill

Drought tolerance was investigated in ‘C306’, one of the most drought tolerant wheat cultivars bred in India in the 1960’s. An intervarietal mapping population of recombinant inbred lines of the cross ‘C306’ × ‘HUW206’ was evaluated for drought tolerance components, namely potential quantum efficiency of photosystem (PS) II (Fv/Fm), chlorophyll content (Chl), flag leaf temperature (Lt), and grain yield per plant (Gyp) under stress. Three independent experiments were conducted under well-watered and water-stressed conditions in greenhouses and growth chambers at Kansas State University (USA). Five hundred and sixty microsatellite markers covering the entire genome were screened for polymorphism between the parents. A QTL (QLt.ksu-1D) for Lt (low flag leaf temperature under stress) on the short arm of chromosome 1D between markers Xbarc271 and Xgwm337 at LOD 3.5 explained 37% of the phenotypic variation. A QTL for Fv/Fm (QF v /F m .ksu-3B) and Chl (QChl.ksu-3B) controlling quantum efficiency of PS II and chlorophyll content under stress were co-localized on chromosome 3B in the marker interval Xbarc68-Xbarc101 and explained 35-40% of the phenotypic variation for each trait. A QTL (QGyp.ksu-4A) for Gyp on chromosome 4A at a LOD value of 3.2 explained 16.3% of the phenotypic variation. Inconsistent QTLs were observed for Fv/Fm on chromosomes 3A, 6A, 2B, 4B, and 4D; for Chl on 3A, 6A, 2B and 4B; and for Lt on 1A, 3A 6A, 3B and 5B. The identified QTLs give a first glimpse of the genetics of drought tolerance in C306 and need to be validated in field experiments using the marker-phenotype linkages reported here.

Genetic dissection of grain yield and physical grain quality in bread wheat (Triticum aestivum L.) under water-limited environments

Posted by Carelia Juarez on , in Journal Articles

Published in Theoretical and Applied Genetics 125 (2): 255-271, 2012

Dion Bennett, Ali Izanloo, Matthew Reynolds, Haydn Kuchel, Peter Langridge and Thorsten Schnurbusch

In the water-limited bread wheat production environment of southern Australia, large advances in grain yield have previously been achieved through the introduction and improved understanding of agronomic traits controlled by major genes, such as the semi-dwarf plant stature and photoperiod insensitivity. However, more recent yield increases have been achieved through incremental genetic advances, of which, breeders and researchers do not fully understand the underlying mechanism(s). A doubled haploid population was utilised, derived from a cross between RAC875, a relatively drought-tolerant breeders’ line and Kukri, a locally adapted variety more intolerant of drought. Experiments were performed in 16 environments over four seasons in southern Australia, to physiologically dissect grain yield and to detect quantitative trait loci (QTL) for these traits. Two stage multi-environment trial analysis identified three main clusters of experiments (forming distinctive environments, ENVs), each with a distinctive growing season rainfall patterns. Kernels per square metre were positively correlated with grain yield and influenced by kernels per spikelet, a measure of fertility. QTL analysis detected nine loci for grain yield across these ENVs, individually accounting for between 3 and 18% of genetic variance within their respective ENVs, with the RAC875 allele conferring increased grain yield at seven of these loci. These loci were partially dissected by the detection of co-located QTL for other traits, namely kernels per square metre. While most loci for grain yield have previously been reported, their deployment and effect within local germplasm are now better understood. A number of novel loci can be further exploited to aid breeders’ efforts in improving grain yield in the southern Australian environment.

 

Genetic differentiation of the wheat leaf rust fungus Puccinia triticina in Europe

Posted by Carelia Juarez on , in Journal Articles

Published in Plant Pathology, 2012

J. A. Kolmer, A. Hanzalova, H. Goyeau, R. Bayles and A. Morgounov

The objective of this study was to determine whether genetically differentiated groups of Puccinia triticina are present in Europe. In total, 133 isolates of P. triticina collected from western Europe, central Europe and Turkey were tested for virulence on 20 lines of wheat with single leaf rust resistance genes, and for molecular genotypes with 23 simple sequence repeat (SSR) markers. After removal of isolates with identical virulence and SSR genotype within countries, 121 isolates were retained for further analysis. Isolates were grouped based on SSR genotypes using a Bayesian approach and a genetic distance method. Both methods optimally placed the isolates into eight European (EU) groups of P. triticina SSR genotypes. Seven of the groups had virulence characteristics of isolates collected from common hexaploid wheat, and one of the groups had virulence characteristics of isolates from tetraploid durum wheat. There was a significant correlation between the SSR genotypes and virulence phenotypes of the isolates. All EU groups had observed values of heterozygosity greater than expected and significant fixation values, which indicated the clonal reproduction of urediniospores in the overall population. Linkage disequilibria for SSR genotypes were high across the entire population and within countries. The overall values of RST and FST were lower when isolates were grouped by country, which indicated the migration of isolates within Europe. The European population of P. triticina had higher levels of genetic differentiation compared to other continental populations.

 

Improved winter wheat genotypes for Central and West Asia

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica, 2012

R. C. Sharma, S. Rajaram, S. Alikulov , Z. Ziyaev, S. Hazratkulova , M. Khodarahami , S. M. Nazeri, S. Belen, Z. Khalikulov, M. Mosaad, Y. Kaya, M. Keser, Z. Eshonova,  A. Kokhmetova, M. G. Ahmedov, M. R. Jalal Kamali  and A. I. Morgounov

High grain yield and resistance to stripe (yellow) rust are the most important traits for successful adoption of winter wheat varieties in Central and West Asia. This study was conducted to determine the stripe rust response and agronomic performance of a set of breeding lines recently developed by the International Winter Wheat Improvement Program (IWWIP). Replicated field studies were conducted in 2010 and 2011 using 38 experimental lines, one regional check (Konya) and one local check. Stripe rust scores were recorded at Karshi, Uzbekistan, and Karaj and Mashhad, Iran, in 2010. Grain yield was recorded at two sites each in Uzbekistan (Karshi and Kibray) and Iran (Karaj and Mashhad) and one site in Turkey (Eskisehir). The test lines showed variation for stripe rust severity, grain yield, 1,000-kernel weight, days to heading and plant height. Several stripe rust resistant genotypes were either higher yielding or equal to the local checks at different sites. Based on stripe rust resistance and yield performance in 2010, a set of 16 genotypes was selected and evaluated in 2011. All 16 were resistant at Almaty, Kazakhstan, and Dushanbe, Tajikistan, in 2011, whereas 9 of the 16 were resistant at Terter, Azerbaijan. The genotypes ‘TCI-02-138, ‘Solh’, ‘CMSS97M00541S’, ‘TCI -2-88(A)’ and ‘TCI-02-88(C)’ were consistently resistant to stripe across all sites in both years. Several lines showed high grain yields and superior agronomic performance across four sites in Uzbekistan and one site in Tajikistan. One genotype has been released in Uzbekistan and another in Tajikistan.

 

Characterization of a cell wall invertase gene TaCwi-A1 on common wheat chromosome 2A and development of functional markers

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Published in Molecular Breeding 29(1): 43-52, 2012

Dongyun Ma, Jun Yan, Zhonghu He, Ling Wu and Xianchun Xia

Cell wall invertase (CWI) is a critical enzyme for sink tissue development and carbon partition, and has a high association with kernel weight. Characterization of Cwi genes and development of functional markers are of importance for marker-assisted selection in wheat breeding. In the present study, the full-length genomic DNA sequence of a Cwi gene located on wheat chromosome 2A, designated TaCwiA1, was characterized by in silico cloning and experimental validation. TaCwiA1 comprises seven exons and six introns, with 3,676 bp in total, and an open reading frame (ORF) of 1,767 bp. A pair of complementary dominant markers, CWI21 and CWI22, was developed based on allelic variations at the TaCwiA1 locus. A 404-bp PCR fragment was amplified by CWI21 in varieties with lower kernel weights, whereas a 402-bp fragment was generated by CWI22 in the varieties with higher kernel weights. The markers CWI21 and CWI22 were located on chromosome 2AL using a F2:3 population from a cross Doumai/Shi 4185, and a set of Chinese Spring nullisomic–tetrasomic lines. They were linked to the SSR locus Xbarc152AL with a genetic distance of 10.9 cM. QTL analysis indicated that TaCwiA1 could explain 4.8% of phenotypic variance for kernel weight over 2 years. Two sets of Chinese landraces and two sets of commercial wheat varieties were used to validate the association of CWI21 and CWI22 with kernel weight. The results indicated that the functional markers CWI21 and CWI22 were closely related to kernel weight and could be used in wheat breeding for improving grain yield.