The rate of annual yield increases for major staple crops must more than double relative to current levels in order to feed a predicted global population of 9 billion by 2050. Controlled ...hybridization and selective breeding have been used for centuries to adapt plant and animal species for human use. However, achieving higher, sustainable rates of improvement in yields in various species will require renewed genetic interventions and dramatic improvement of agricultural practices. Genomic prediction of breeding values has the potential to improve selection, reduce costs and provide a platform that unifies breeding approaches, biological discovery, and tools and methods. Here we compare and contrast some animal and plant breeding approaches to make a case for bringing the two together through the application of genomic selection. We propose a strategy for the use of genomic selection as a unifying approach to deliver innovative 'step changes' in the rate of genetic gain at scale.
Advancements in genotyping are rapidly decreasing marker costs and increasing genome coverage. This is facilitating the use of marker-assisted selection (MAS) in plant breeding. Commonly employed MAS ...strategies, however, are not well suited for agronomically important complex traits, requiring extra time for field-based phenotyping to identify agronomically superior lines. Genomic selection (GS) is an emerging alternative to MAS that uses all marker information to calculate genomic estimated breeding values (GEBVs) for complex traits. Selections are made directly on GEBV without further phenotyping. We developed an analytical framework to (i) compare gains from MAS and GS for complex traits and (ii) provide a plant breeding context for interpreting results from studies on GEBV accuracy. We designed MAS and GS breeding strategies with equal budgets for a high-investment maize (Zea mays L.) program and a low-investment winter wheat (Triticum aestivum L.) program. Results indicate that GS can outperform MAS on a per-year basis even at low GEBV accuracies. Using a previously reported GEBV accuracy of 0.53 for net merit in dairy cattle, expected annual gain from GS exceeded that of MAS by about threefold for maize and twofold for winter wheat. We conclude that if moderate selection accuracies can be achieved, GS could dramatically accelerate genetic gain through its shorter breeding cycle.
El mejoramiento de plantas es un proceso lento. Desarrollar nuevas variedades de cultivos como arveja necesita de una década o más, usando la metodología tradicional. Un sistema llamado Speed ...Breeding fue desarrollado en diferentes cultivos. Incluye el crecimiento de plantas en cámaras de cultivos o invernaderos, usando luz artificial con fotoperiodos inductivos, temperatura y humedad controlada y cosecha anticipada de granos. El objetivo del trabajo fue desarrollar un sistema de Speed Breeding para arveja. Se utilizó un sistema hidropónico, con fotoperiodo de 22 horas, antigiberelina Flurprimidol y cosecha anticipada de granos (24 días después de antesis). Se evaluaron diferentes variedades que fueron comparadas con los mismos materiales evaluados a campo, obteniéndose reducciones de altura dentro del 52 y 63%, días a floración entre 46 y 57 días (mientras que los mismos materiales a campo florecieron entre 91 y 96 días) y eficiencias entre el 51 y el 93%, siendo las variedades semiafilas las que presentaron un mayor valor. Luego, el mismo sistema fue evaluado sobre dos poblaciones segregantes durante dos generaciones. Obteniendo eficiencias entre 74% y 78%, días a floración entre 41 y 47 días y disminuyendo la altura de la planta entre 52% y 63%. Se evaluaron hibridaciones entre variedades. Se tuvieron resultados alentadores, permitiendo desarrollar un sistema integral de mejora incluyendo hibridación y conducción de materiales segregantes. Este sistema permitió aumentar la eficiencia de los programas significativamente, reduciendo el espacio necesario (266 plantas/m2), reduciendo considerablemente costos y labores, obteniendo 5 generaciones por año de arvejas.
Nuevas tecnologías y disciplinas como son la bioinformática, la secuenciación de última generación y la genómica funcional están permitiendo obtener una amplia y creciente gama de marcadores ...moleculares de genes de interés agronómico en trigo. Sin embargo, los tiempos biológicos de avance en el mejoramiento convencional limitan considerablemente la velocidad con que la aplicación de estos conocimientos llega a materiales mejorados. En este sentido, existe la necesidad de contar con herramientas para favorecer el avance genético y la selección asistida por marcadores en lapsos de tiempos menores que los obtenidos por el mejoramiento convencional. La técnica de speed breeding (mejoramiento acelerado) aporta soluciones para esta problemática. En la EEA Marcos Juárez, sede del programa nacional de mejoramiento de trigo de INTA, se construyó una plataforma de speed breeding de bajo presupuesto que se está usando para: a) acortar significativamente los tiempos necesarios para la estabilización de poblaciones segregantes; b) enriquecer líneas estabilizadas con alelos favorables de genes de interés agronómico; y c) dar respuesta a necesidades específicas del programa, como la introgresión de caracteres de difícil visualización a campo. El objetivo de esta disertación es transmitir nuestra experiencia en la temática a otros grupos de trabajo que estén interesados en empezar a utilizarla.
In recent years, genome editing, using a system called CRISPR (clustered regularly interspaced short palindromic repeats) has raised incredible new possibilities for citrus improvement. CRISPR is ...being used to make small changes in the DNA sequence of citrus trees, resulting in specifically targeted mutations. Major advances in the ability to decipher the genetic blueprint of any living organism, including citrus, have been made possible by the development of new genome-sequencing technologies and powerful computers. Many commercially important citrus types have been or are in the process of being sequenced. Peer reviewed through UF/IFAS Citrus Research and Education Center; published in Citrus Industry Magazine.
A substantial increase in grain yield potential is required, along with better use of water and fertilizer, to ensure food security and environmental protection in future decades. For improvements in ...photosynthetic capacity to result in additional wheat yield, extra assimilates must be partitioned to developing spikes and grains and/or potential grain weight increased to accommodate the extra assimilates. At the same time, improvement in dry matter partitioning to spikes should ensure that it does not increase stem or root lodging. It is therefore crucial that improvements in structural and reproductive aspects of growth accompany increases in photosynthesis to enhance the net agronomic benefits of genetic modifications. In this article, six complementary approaches are proposed, namely: (i) optimizing developmental pattern to maximize spike fertility and grain number, (ii) optimizing spike growth to maximize grain number and dry matter harvest index, (iii) improving spike fertility through desensitizing floret abortion to environmental cues, (iv) improving potential grain size and grain filling, and (v) improving lodging resistance. Since many of the traits tackled in these approaches interact strongly, an integrative modelling approach is also proposed, to (vi) identify any trade-offs between key traits, hence to define target ideotypes in quantitative terms. The potential for genetic dissection of key traits via quantitative trait loci analysis is discussed for the efficient deployment of existing variation in breeding programmes. These proposals should maximize returns in food production from investments in increased crop biomass by increasing spike fertility, grain number per unit area and harvest index whilst optimizing the trade-offs with potential grain weight and lodging resistance.
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