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Breeding wheat with enhanced levels of grain zinc (Zn) and iron (Fe) is a cost-effective, sustainable solution to malnutrition problems. Modern wheat varieties have limited variation in grain Zn and Fe, but large-scale screening has identified high levels of Zn and Fe in wild relatives and progenitors of cultivated wheat. The most promising sources of high Zn and Fe are einkorn (Triticum monococcum), wild emmer (T. dicoccoides), diploid progenitors of hexaploid wheat (such as Aegilops tauschii), T. spelta, T. polonicum, and landraces of T. aestivum. This study evaluate the effects of translocations from rye and different Aegilops species in a “Pavon-76” wheat genetic background and utilized in the wheat biofortification breeding program at CIMMYT that uses diverse genetic resources, including landraces, recreated synthetic hexaploids, T. spelta and pre-breeding lines. Four translocations were identified that resulted significantly higher Zn content in “Pavon 76” genetic background than the check varieties, and they had increased levels of grain Fe as well-compared to “Pavon 76.” These lines were also included in the breeding program aimed to develop advanced high Zn breeding lines. Advanced lines derived from diverse crosses were screened under Zn-enriched soil conditions in Mexico during the 2017 and 2018 seasons. The Zn content of the grain was ranging from 35 to 69 mg/kg during 2017 and 38 to 72 mg/kg during 2018. Meanwhile grain Fe ranged from 30 to 43 mg/kg during 2017 and 32 to 52 mg/kg during 2018. A highly significant positive correlation was found between Zn and Fe (r = 0.54; P < 0.001) content of the breeding lines, therefore it was possible to breed for both properties in parallel. Yield testing of the advanced lines showed that 15% (2017) and 24% (2018) of the lines achieved 95–110% yield potential of the commercial checks and also had 12 mg/kg advantage in the Zn content suggesting that greater genetic gains and farmer-preferred wheat varieties were developed and deployed. A decade of research and breeding efforts led to the selection of “best-bet” breeding lines and the release of eight biofortified wheat varieties in target regions of South Asia and in Mexico.
Dengcai Liu (2018)
In recent years, wheat yield per hectare appears to have reached a plateau, leading to concerns for future food security with an increasing world population. Since its invention, synthetic hexaploid wheat (SHW) has been shown to be an effective genetic resource for transferring agronomically important genes from wild relatives to common wheat. It provides new sources for yield potential, drought tolerance, disease resistance, and nutrient-use efficiency when bred conventionally with modern wheat varieties. SHW is becoming more and more important for modern wheat breeding. Here, we review the current status of SHW generation, study, and application, with a particular focus on its contribution to wheat breeding. We also briefly introduce the most recent progress in our understanding of the molecular mechanisms for growth vigor in SHW. Advances in new technologies have made the complete wheat reference genome available, which offers a promising future for the study and applications of SHW in wheat improvement that are essential to meet global food demand.
Tesis (Maestría en Ciencias, especialista en Genética).- Colegio de Postgraduados, 2015.
La enfermedad Septoria tritici blotch ocasionada por Zymoseptoria tritici es una de las principales enfermedades del trigo y puede causar grandes pérdidas en el rendimiento de su producción mundial. El control de la enfermedad ha sido una tarea ardua que incluye distintas técnicas, pero la resistencia genética del huésped es un elemento fundamental para su control eficaz. En la presente investigación se identificaron los marcadores moleculares ligados a la resistencia a Septoria tritici blotch mediante el mapeo de QTL de una población con 193 líneas recombinantes puras. Los padres de la población son una línea con origen en Marruecos llamada NASMA susceptible y una línea con origen en CIMMYT llamada RPB709.71/COC resistente a la enfermedad. Utilizando los marcadores moleculares de Secuencias Simples Repetidas y los Polimorfismos de un Solo Nucleótido se identificaron tres QTL en los cromosomas; 3 BL, 5 AL y 7 AS, ligados a la resistencia a Septoria tritici blotch en la fase adulta estables en cuatro ambientes de campo; en Toluca y en el Rancho Bóximo, Jiquipilco, en el Estado de México en los ciclos de evaluación 2010 y 2011. Estos resultados son de gran importancia debido a que la mayoría de las investigaciones para la resistencia a la enfermedad se realizan en la fase de plántula en invernadero y se conoce poco de la resistencia en la fase adulta en campo. _______________ ABSTRACT: Septoria tritici blotch disease caused by Zymoseptoria tritici is one of the major diseases of wheat and can cause large losses in yield of its global production. The disease control has been an arduous task involving different techniques, but the genetic resistance of the host is a key element for effective control. In this project we identified molecular markers linked to resistance to Septoria tritici blotch by QTL mapping using a population of 193 recombinant inbred lines. The parents of the population were a susceptible line from Morocco called NASMA and a disease resistant line from CIMMYT called RPB709.71/COC. Using the molecular marker technologies, Simple Sequence Repeats and Single Nucleotide Polymorphisms we found three QTL on chromosomes 3BL, 5AL and 7AS linked to resistance to Septoria tritici blotch in the adult-plant stage consistent across four different field environments in Toluca and in Bóximo, Jiquipilco, in the State of Mexico in 2010 and 2011. These results are of great importance because previous research for this disease resistance was mainly performed at the seedling stage in the greenhouse. Little is known about the resistance at adult-plant stage in the field.
JOSE LUIS GARCIA FRANCO (2013)
Tesis (Maestría en Ciencias, especialista en Botánica).- Colegio de Postgraduados, 2013.
Phalaris minor Retz. (“alpistillo”) es considerada como una maleza importante en el cultivo de trigo en la región del Bajío Mexicano, que ha desarrollado resistencia a herbicidas inhibidores de la Acetil Coenzima A Carboxilasa (ACCasa). Se ha consignado que más de la mitad de la población de Phalaris spp. comúnmente escapa del control manual a causa de la similitud morfológica con el cultivo de trigo. El objetivo de la presente investigación fue determinar si existen diferencias morfológicas y fenológicas entre biotipos resistentes y susceptible de P. minor a los herbicidas, y cultivares de trigo. Se realizaron experimentos en Montecillo, México en condición de no competencia. Se emplearon cuatro biotipos de alpistillo resistentes y uno susceptible, además, las variedades de trigo Cortazar y Nana para compararlas con los biotipos de la maleza en la fase vegetativa. Las semillas se pusieron a germinar en cajas Petri en condiciones de laboratorio y se trasplantaron a macetas de 3 L de capacidad que contenían como sustrato una mezcla (1:1) de tierra de monte y arena. Se registraron los atributos morfológicos y fenológicos de las plantas durante su ciclo biológico. Los datos se analizaron independientemente mediante las técnicas de componentes principales y análisis discriminante. Los resultados mostraron que existen diferencias morfológicas entre los biotipos de alpistillo, lo cual sugiere que la resistencia se desarrolló en forma independiente en los biotipos y que no fue una población resistente inicial de la cual ocurriera la dispersión. Se mostró que existe una separación estadística entre los biotipos de alpistillo y las variedades de trigo, por lo que es factible diferenciarlos en estado de plántula. En cuanto a la fenología de alpistillo, existe una separación de biotipos; de los resistentes, tres presentaron un ciclo biológico más corto que el susceptible, por lo que la dispersión de sus semillas podría tener mayor éxito. _______________ MORPHOLOGICAL CHARACTERIZATION AND PHENOLOGY OF RESISTANTS AND SUSCEPTIBLE Phalaris minor RETZ. BIOTYPES TO ACCase INHIBITORS. ABSTRACT: Phalaris minor Retz. ("Little-seed canary grass") is considered an important weed of the wheat crop in the Bajio Mexicano region, which has developed resistance to herbicides inhibitors of acetyl coenzyme A carboxylase (ACCase). Has been recorded that more than half of the population of Phalaris spp. commonly escapes to manual control because of the morphological similarity with wheat. The aim of this investigation was to determine whether morphological and phenological differences exist between resistant and susceptible biotypes of P. minor to herbicides, and wheat cultivars. Experiments were conducted in Montecillo, Mexico in a not competition condition at a greenhouse. We used four resistant biotypes and a susceptible one, also, the wheat cultivars Cortazar and Nana to compare weed biotypes in the vegetative stage. The seeds were germinated in Petri dishes in laboratory and transplanted into pots of 3 L capacity containing as a substrate a mixture (1:1) of forest soil and sand. Were recorded morphological and physiological attributes of plants during their life cycle. Data was analyzed independently using the techniques of principal components and discriminant analysis. The results showed that there are morphological differences between alpistillo biotypes, this suggests that resistance evolved in an independent way in the biotypes and it was not from an initial resistant population that the dispersal occurred. It showed that there is a statistical separation between alpistillo biotypes and wheat cultivars, making it possible to distinguish them visually at seedling stage. Regarding the phenology of alpistillo biotypes, exist a statistical separation; from resistant, three had a biological cycle shorter than the susceptible, so the seed dispersal may be more successful.
The cyst nematode heterodera filipjevi is a plant parasite causing substantial yield loss in wheat. Resistant cultivars are the preferred method of controlling cyst nematodes. Association mapping is a powerful approach to detect associations between phenotypic variation and genetic polymorphisms; in this way favorable traits such as resistance to pathogens can be located. Therefore, a genome-wide association study of 161 winter wheat accessions was performed with a 90k iselect single nucleotide polymorphism (snp) chip. Population structure analysis grouped into two major subgroups and first principal component accounted 6.16% for phenotypic diversity. The genome-wide linkage disequilibrium across wheat was 3 cm. Eleven quantitative trait loci (qtls) on chromosomes 1al, 2as, 2bl, 3al, 3bl, 4as, 4al, 5bl, and 7bl were identified using a mixed linear model false discovery rate of p < 0.01 that explained 43% of total genetic variation. This is the first report of qtls conferring resistance to h. filipjevi in wheat. Eight qtls on chromosomes 1al, 2as, 2bl, 3al, 4al, and 5bl were linked to putative genes known to be involved in plant−pathogen interactions. Two other qtls on 3bl and one qtl on 7bl linked to putative genes known to be involved in abiotic stress.
Monica Mezzalama (2013)
Este documento tiene como propósito proporcionar lineamientos generales que promueven el desplazamiento seguro del germoplasma desde y hasta las oficinas del CIMMYT. Los presentes lineamientos contienen mucha información de “sentido común” que resulta útil y fácil de consultar. La sección relativa a los requisitos de cada país será actualizada cada año y también se agregarán nuevas fuentes de información y referencias.
Wheat is planted through the broadcast method on 7.8 million ha and irrigated through low-efficiency flood basin irrigation methods. With decreased water availability, there is a need to adopt water use efficient planting techniques. The current paper uses two-year trials data set as well as farmer survey data to demonstrate benefits of ridge-furrow planting wheat and farmer perception regarding the technology in Pakistan. During 2014–15 and 2015–16, ridge-furrow planting of wheat was compared with farmer practice of planting on flat surface through broadcasting at 162 sites located in 15 districts of Pakistan. In a survey, 134 farmers shared their experiences about ridge-furrow planting. Data collected from field trials and demonstrations showed that better tillering and crop growth contributed towards 12% higher wheat grain yield with ridge-furrow planting in comparison with the farmer practice of flat planting in all 15 districts during both years. Furrow-irrigated ridge planting of wheat helped farmers in saving of 30–35% water in comparison with farmer practice. Farmers adopting ridge-furrow wheat planting earned USD 100.63 per hectare more profit than nonadopter farmers. Adoption of this technology on one million hectare can help in saving 1 million acre foot of water and produce additional 0.36 million tons of wheat per year.
Matthew Paul Reynolds (2012)
Most introductions addressing cereal breeding begin with the Green Revolution. This one is no exception. While this Foreword is certainly not an attempt to write the history of crop physiology and breeding for abiotic stress or give credits, a few landmarks should be noticed on the long road arriving at this important publication. Since the new generation of researchers is not in the habit of reading anything older than three years, I am obliged to provide a brief perspective, having age to my advantage. Looking back at the road will point you to the way ahead. The Green Revolution which consisted of a large increase in cereal grain yield took place in wheat and rice towards the mid-Twentieth Century. It was driven by wheat and rice breeders who sought to reduce plant height in order to reduce lodging and thus also allow for increased nitrogen fertilization. The "Green Revolution" in sorghum (which was not defined as such when it took place) was also driven by a reduction in plant height and took place several decades earlier. It was not directed at increasing yield but rather towards achieving a "combine height" dwarf sorghum that could be harvested mechanically. The bonus of these modifications was an increase in grain yield potential.