Posts Tagged ‘Triticum aestivum’

Evaluation of advance wheat lines for agronomic traits in rainfed environment

Posted by Carelia Juarez on , in Journal Articles

Published in Pakistan Journal Agricultural Research 27 (279-88, 2014.

Sohail, M.; Hussain, I.; Din, R.;Tanveer, S.K.; Qamar, M.; Abbas, S.H.

Wheat under rainfed conditions of Pothwar region of Pakistan is usually exposed to limited soil moisture during early growth period and high temperature stress during reproductive growth stage. Better yield under stressful environment is the main objective while evaluating genotypes for rainfed ecologies. A field study was conducted at National Agricultural Research Centre (NARC), Islamabad, Pakistan to evaluate the agronomic traits of three advance lines (NR-397, NR-379 and NR-400) in comparison to released variety (NARC-09) under rainfed conditions during crop season 2010-2011. Crop was sown on normal (November 15) and late (December 15) planting times to create variable growing conditions especially during reproductive growth period. The adverse effect of the late planting was significant (P<0.05) on grain yield of the crop. Late planting produced 29% lower grain yield than normal planting. Genotypes also showed significant variation (P<0.05) regarding grain yield production under both normal and late sowing dates. Under more stressful growing conditions (late planting), minimum grain yield reduction was noticed in line NR-397 (19%) followed by NARC-09 (20%), NR-400 (30%) and NR-379 (35%). Late planting conditions also signi- -2 ficantly reduced days to maturity, spikes m and 1000-grain weight in all genotypes as compared to normal sowing; however, the reduction in these parameters were significantly less (P<0.05) in wheat lines NR-397 and NARC-09 as compared to other two genotypes. Results showed that comparatively higher grain yields of lines NR-397 and NARC-09 were correlated to their better leaf chlorophyll retention and maintenance of low canopy temperature during grain filling periods particularly under late planting conditions. Findings of this study have indications that wheat sowing up to November 15 is more appropriate time and advance lines NR- 397 and NARC-09 have the genetic potential to tolerate adverse rainfed growing conditions under agro-ecological conditions of Pothwar region, Pakistan.

Temperature adaptation in Australasian populations of Puccinia striiformis f. sp. tritici.

Posted by Carelia Juarez on , in Journal Articles

Published in Plant Pathology 63 (3572-580, 2014

Loladze, A.; Druml, T.; Wellings, C.R.

Stripe rust, caused by Puccinia striiformis f. sp. tritici, is one of the major fungal pathogens of wheat. A new pathotype was introduced to Australia in 2002 and several derivative pathotypes were detected in subsequent seasons. It has been suggested that the severity of stripe rust outbreaks in Australia since 2002 could be as a result of traits other than virulence in the pathogen population. This study was conducted to investigate the hypothesis that the stripe rust pathogen population dominant in Australia since 2002 was better adapted to warm temperature conditions compared to previous pathogen populations. Sixteen pathotypes were selected to examine the influence of two contrasting temperature regimes during the 24 h incubation (10°C and 15°C) and the subsequent post-inoculation (17°C and 23°C) periods on latent period and infection efficiency on four susceptible wheat cultivars. In addition, the effect of two contrasting incubation temperatures on urediniospore germination was examined. The results indicated that pathotypes of P. striiformis f. sp. tritici detected after 2002 did not show evidence of adaptation to high temperatures, which suggests that other factors contributed to the observed increased aggressiveness.

Resistance of slow mildewing genes to stripe rust and leaf rust in common wheat

Posted by Carelia Juarez on , in Journal Articles

Published in Acta Agronomica Sinica 40(9) : 1157-1564, 2014

Liu Jin-Dong; Chen Xin-Min; He Zhonghu; Wu Ling; Bai Bin; Li Zai-Feng; Xia Xian-Chun

Pyramiding quantitative trait loci (QTLs) is an effective method to improve resistance to powdery mildew, stripe rust, and leaf rust in common wheat. We have developed 21 lines (F6) carrying 2-5 slow mildewing QTLs by crossing slow powdery mildew cultivars Bainong 64 and Lumai 21 possessing four and three slow mildewing QTLs, respectively. These Flines were evaluated in the field in Pianxian, Sichuan and Tianshui, Gansu for stripe rust resistance and in Baoding, Hebei and Zhoukou, Henan for leaf rust resistance during the 2012-2013 cropping season. According to the maximum disease severities (MDS) and the area under the disease progress curve (AUDPC), QTLs QPm.caas-4DLQPm.caas-6BS and QPm.caas-2BL were highly resistant to stripe rust (P < 0.01), which explained 16.9%, 14.1%, and 17.3% of phenotypic variance, respectively. Locus QPm.caas-4DL also showed high resistance to leaf rust (P < 0.01) with phenotypic contribution of 35.3%. Lines that pyramided five (QPm.caas-1A/QPm.caas-4DLQPm.caas-2DL/QPm.caas-2BS/QPm.caas-2BL) and four (QPm.caas-1A/QPm.caas-4DL/QPm.caas-2BS/QPm.caas-2BL) QTLs exhibited higher resistance to both stripe and leaf rust compared with their parents. This result indicates that the combination of QPm.caas-4DL (from Bainong 64), QPm.caas-2BS and QPm.caas-2BL (Lumai 21) has a marked effect on improving adult resistance to powdery mildew, stripe rust and leaf rust, and the more QTLs are pyramided, the stronger slow disease resistance can be achieved. In breeding practice, the combination of 4-5 slow mildewing or rusting QTLs can result in durable resistance to multiple diseases.

QTL characterization of resistance to leaf rust and stripe rust in the spring wheat line Francolin#1

Posted by Carelia Juarez on , in Journal Articles

Published in Molecular Breeding, 2014

Caixia Lan;Rosewarne, G.M.; Singh, R.P.; Herrera-Foessel, S.A.; Huerta-Espino, J.; Basnet, B.R.; Yelun Zhang; Ennian Yang.

Growing resistant wheat varieties is a key method of controlling two important wheat diseases, leaf rust and stripe rust. We analyzed quantitative trait loci (QTL) to investigate adult plant resistance (APR) to these rusts, using 141 F5 RILs derived from the cross ‘Avocet-YrA/Francolin#1’. Phenotyping of leaf rust resistance was conducted during two seasons at Ciudad Obregon, Mexico, whereas stripe rust was evaluated for two seasons in Toluca, Mexico, and one season in Chengdu, China. The genetic map was constructed with 581 markers, including diversity arrays technology and simple sequence repeat. Significant loci for reducing leaf rust severity were designated QLr.cim1BLQLr.cim3BS.1QLr.cim3DC, and QLr.cim7DS. The six QTL that reduced stripe rust severity were designated QYr.cim1BLQYr.cim2BSQYr.cim2DSQYr.cim3BS.2QYr.cim5AL, andQYr.cim6AL. All loci were conferred by Francolin#1, with the exception of QYr.cim2DSQYr.cim5AL, and QYr.cim6AL, which were derived from Avocet-YrA. Closely linked markers indicated that the 1BL locus was the pleiotropic APR gene Lr46/Yr29QYr.cim2BS was a seedling resistance gene designated as YrF that conferred intermediate seedling reactions and moderate resistance at the adult plant stage in both Mexican and Chinese environments. Significant additive interactions were detected between the six QTL for stripe rust, but not between the four QTL for leaf rust. Furthermore, we detected two new APR loci for leaf rust in common wheat: QLr.cim3BS.1 andQLr.cim7DS.

Variation at glutenin subunit loci, single kernel characterization and evaluation of grain protein in East African bread wheat varieties

Posted by Carelia Juarez on , in Journal Articles

Published in Euphytica, 2014

Macharia, G.K.; Peña Bautista, R.J.; Simsek, S.; Anderson, J.A.

Wheat breeding programs worldwide aim at developing cultivars that meet end user quality attributes demanded by producers, processors, and consumers. Selecting from breeding populations created from well characterized parental germplasm provides the best opportunity of identifying cultivars that combine the best alleles and grain phenotypes for the desired technological applications. In this study, 216 bread wheat lines associated with Ethiopian and Kenyan breeding programs including a few founder lines were profiled for high molecular weight glutenin subunits and low molecular weight glutenin subunits by SDS-PAGE. Additionally, total crude protein, relative puroindoline content by SDS-PAGE, kernel diameter, kernel weight and kernel hardness by SKCS were determined. Extensive allelic variation at the glutenin subunit loci was found, with GluB1 and GluB3 having highest diversity across subpopulations. Relative to wild type cultivar ‘Alpowa-1-soft’, the founder line BW21 had the lowest puroindoline content. The frequencies of soft and very soft wheat classes were lowest in the Ethiopian subpopulation and highest among the Kenyan lines. Accordingly, 12 lines considered to have optimal combinations of glutenin subunit alleles and kernel characteristics were highlighted and recommended for cultivar improvement.

Progress towards genetics and breeding for minor genes based resistance to Ug99 and other rusts in CIMMYT high yielding spring wheat

Posted by Carelia Juarez on , in Journal Articles

Published in Journal of Integrative Agriculture 13 (2) : 255-261, 2014

Singh, R.P.; Herrera-Foessel, S.; Huerta-Espino, J.; Sukhwinder Singh; Bhavani, S.; Caixia Lan;Basnet, B.R.

Wheat rusts continue to cause significant losses worldwide despite major efforts given to their genetic control. This is due to frequent evolution and selection of virulence in pathogen overcoming the deployed race-specific resistance genes. Although the life of effective race-specific resistance genes can be prolonged by using gene combinations, an alternative approach being implemented at CIMMYT is to deploy varieties that posses adult plant resistance (APR) based on combinations of minor, slow rusting genes. When present alone, the APR genes do not confer adequate resistance especially under high disease pressure; however, combinations of 4 or 5 minor genes usually result in “near-immunity” or a high level of resistance. Although only a few APR genes are catalogued, various APR QTL are now known and could lead to further characterization of additional genes. Four characterized genes have pleiotropic effects in conferring partial APR to all three rusts and powdery mildew, thus simplifying the task of breeding wheat varieties that are resistant to multiple diseases. Significant progress was made recently in developing high-yielding wheat germplasm that possesses high levels of APR to all three rusts by implementing a Mexico-Kenya shuttle breeding scheme. Parents with APR to Ug99 were hybridized with high yielding parents that had adequate to high levels of APR to leaf rust and yellow rust. Segregating populations and advanced lines from these crosses were selected under high rust pressures in Mexico (leaf rust and yellow rust) and Kenya (Ug99 stem rust and yellow rust) to identify high yielding progenies that possess high to adequate APR to all three rusts. International distribution of these high yielding wheats is underway through CIMMYT international yield trials and screening nurseries. It is expected that several wheat varieties with APR to three rusts will be released and grown in various countries in the near-future that will allow determining the durability of resistance.

QTL mapping for adult plant resistance to powdery mildew in Italian wheat cv. Strampelli

Posted by Carelia Juarez on , in Journal Articles

Published in Journal of Integrative Agriculture 12 (5) : 756-764, 2013

Muhammad Azeem Asad; Bin Bai; Cai-Xia Lan; Jun Yan; Xian-chun Xia; Yong Zhang; He Zhonghu

The Italian wheat cv. Strampelli displays high resistance to powdery mildew caused by Blumeria graminis f. sp. tritici. The objective of this study was to map quantitative trait loci (QTLs) for resistance to powdery mildew in a population of 249 F2:3 lines from Strampelli/Huixianhong. Adult plant powdery mildew tests were conducted over 2 yr in Beijing and 1 yr in Anyang and simple sequence repeat (SSR) markers were used for genotyping. QTLs Qpm.caas-3BS, Qpm.caas-5BL.1, and Qpm.caas-7DS were consistent across environments whereas, Qpm.caas-2BS.1 found in two environments, explained 0.4–1.6, 5.5–6.9, 27.1–34.5, and 1.0–3.5% of the phenotypic variation respectively. Qpm.caas-7DS corresponded to the genomic location of Pm38/Lr34/Yr18. Qpm.caas-4BL was identified in Anyang 2010 and Beijing 2011, accounting for 1.9–3.5% of phenotypic variation. Qpm.caas-2BS.1 and Qpm.caas-5BL.1 contributed by Strampelli andQpm.caas-3BS by Huixianhong, seem to be new QTL for powdery mildew resistance. Qpm.caas-4BL, Qpm.caas-5BL.3, and Qpm.caas-7DS contributed by Strampelli appeared to be in the same genomic regions as those mapped previously for stripe rust resistance in the same population, indicating that these loci conferred resistance to both stripe rust and powdery mildew. Strampelli could be a valuable genetic resource for improving durable resistance to both powdery mildew and stripe rust in wheat.

Synthetic Hexaploids: Harnessing species of the primary gene pool for wheat improvement

Posted by Carelia Juarez on , in Journal Articles

Published in Plant Breeding Reviews 37 : 35-122, 2013

Ogbonnaya, F.C.;Abdalla, O.; Mujeeb-Kazi, A.; Kazi, A.G.; Xu, S.S.; Gosman, N.; Lagudah, E.S.; Bonnett, D.G.; Sorrells, M.E.; Tsujimoto, H.

Incorporation of genetic diversity into elite wheat (Triticum aestivum L., 2n¼6x¼42, AABBDD) cultivars has long been recognized as a means of improving wheat productivity and securing global wheat supply. Synthetic hexaploid wheat (SHW) genotypes recreated from its two progenitor species, the tetraploid, Triticum turgidum (2n¼4x¼28, AABB) and its diploid wild relative, Aegilops tauschii (2n¼2x¼14, DD) are a useful resource of new genes for hexaploid wheat improvement. These include many productivity traits such as abiotic (drought, heat, salinity/sodicity, and waterlogging) and biotic (rusts, septoria, barley yellow dwarf virus (BYDV), crownrot, tanspot, spot blotch, nematodes,powderymildew, and fusarium head blight) stress resistance/tolerances as well as novel grain quality traits. Numerous SHWs have been produced globally by various institutions including CIMMYT-Mexico, ICARDA-Syria, Department of Primary Industries (DPI), Victoria-Australia, IPK-Germany, Kyoto University-Japan, and USDAARS. This review examines the varied aspects in the utilization of synthetics for wheat improvement including the traits and genes identified, mapped, and transferred to common wheat. It has also been demonstrated that synthetic backcross- derived lines (SBLs, i.e., when SHW is crossed to adapted local bread varieties) show significant yield increases and thus, enhanced yield performance across a diverse range of environments, demonstrating their potential for improving wheat productivity worldwide. This is particularly evident in moisture limited environments. The use of SBLs, advanced backcross QTL analysis, chromosome introgression lines, and whole genome association mapping is contributing to the elucidation of the genetic architecture of some of the traits. The contribution of transgressive segregation to enhanced phenotypes and the mechanisms including its genetic and physiological basis are yet to be elucidated. Understanding these would further enhance the utility of SBLs. Considerable progress has beenmade in the identification of useful quantitative trait loci (QTL) and genes; however the transfer of such rich genetic diversity into elite wheat cultivars is still quite limited. Gaps still exist in data cataloging; and access to such information could serve as an important community resource. Future production of new SHWshould extend to under-exploited AB genome tetraploids such as T. turgidum ssp. carthlicum, T. turgidum ssp. dicoccum, and T. turgidum ssp. dicoccoides and identifying gaps in the Ae. tauschii germplasm used for existing SHW. Identifying geographical areas where the progenitor species of the existing SHW were collected would assist in guiding future collection missions. The recent advances in molecular technologies with whole genome sequencing becoming affordable will provide researchers with opportunities for more detailed analysis of traits and the deployment of more efficient strategies in the use of the unique exotic alleles derived from SHW for common wheat improvement. Thus, the contribution of SHW and the derived SBLs to wheat cropping systems worldwide is likely to grow in significance. However, these potential benefits are only realizable if phenotyping is equally extensive and effective.

Quantitative trait loci of stripe rust resistance in wheat

Posted by Carelia Juarez on , in Journal Articles

Published in Theoretical and Applied Genetics 126 (10) : 2427-2449, 2013

Rosewarne, G.M.; Herrera-Foessel, S.A.; Singh, R.P.; Huerta-Espino, J.; Lan Caixia; He Zhonghu

Over thirty publications during the last 10 years have identified more than 140 QTLs for stripe rust resistance in wheat. It is likely that many of these QTLs are identical genes that have been spread through plant breeding into diverse backgrounds through phenotypic selection under stripe rust epidemics. Allelism testing can be used to differentiate genes in similar locations but in different genetic backgrounds; however, this is problematic for QTL studies where multiple loci segregate from any one parent. This review utilizes consensus maps to illustrate important genomic regions that have had effects against stripe rust in wheat, and although this methodology cannot distinguish alleles from closely linked genes, it does highlight the extent of genetic diversity for this trait and identifies the most valuable loci and the parents possessing them for utilization in breeding programs. With the advent of cheaper, high throughput genotyping technologies, it is envisioned that there will be many more publications in the near future describing ever more QTLs. This review sets the scene for the coming influx of data and will quickly enable researchers to identify new loci in their given populations.

Molecular mapping of high temperature tolerance in bread wheat adapted to the Eastern Gangetic Plain region of India

Posted by Carelia Juarez on , in Journal Articles

Published in Field Crops Research, 2013

Tiwari, C.; Wallwork, H.; Kumar, U.; Dhari, R.; Arun, B.; Mishra, V.K.; Reynolds, M.P.; Joshi, A.K.

The inheritance of tolerance to high temperature stress during the grain filling period was investigated via a QTL analysis based on 138 doubled haploid progeny of a cross between the wheat cultivars Berkut and Krichauff. Performance data were collected from three seasons, in each of which the material was planted both at the conventional time and a month later. A heat sensitivity index (HSI) was also used to monitor the effect of high temperature on grain yield, thousand grain weight, grain filling duration and canopy temperature. Using composite interval mapping, seven stable QTL were identified for HSI of traits, mapping to chromosomes 1D, 6B, 2D and 7A. Three of the QTL related to HSI of grain filling duration, two to thousand grain weight and one each to grain yield and canopy temperature. A region of chromosome 1D harbored a QTL determining HSI of both thousand grain weight and canopy temperature. The QTL analysis for the direct traits GY, TGW, GFD and CT led to detection of 22 QTLs spread over to 17 chromosomal regions. Of these 13 QTLs were shown under normal sown, while 9 under the heat stress. A QTL for TGW on chromosome 6B under normal sown co-located with HSI(TGW) QTL QHTgw.bhu-6BL. QTL × environment interactions were not observed for any of the grain filling duration associated loci.