Molecular breeding

About: Molecular breeding is a research topic. Over the lifetime, 2120 publications have been published within this topic receiving 56908 citations.

Genomics-based breeding in forest trees: are we there yet?

Abstract: Efforts to develop genetic marker based approaches to breeding forest trees began in the late 1980s. Approaches based on first generation of markers, allozymes, were not feasible due to the very limited number of markers (<50). The first DNA-based markers, RFLPs, brought more hope as moderately dense genetic maps could be constructed to scan the genome and map quantitative trait loci (QTLs). This approach was quite effective toward mapping QTLs in many forest tree species but the approach could not be brought to application in tree breeding due to low levels of linkage disequilibrium (LD) in forest tree breeding populations and recombination between flanking markers and QTLs with each generation. The next generation of DNA markers based of the polymerase chain reaction (PCR), RAPD, AFLP and SSR, did not solve the LD and recombination problem, even though more markers were available and throughput increased. The situation began to change in the early 2000s with the availability of automated DNA sequencing technology and single nucleotide polymorphism (SNP) genetic markers. Now association studies could be performed where SNPs within candidate genes controlling complex traits could be identified and thus “solving” or minimizing the LD and recombination limitation. This approach to complex trait dissection has been widely applied in forest trees and the early approach of QTL mapping in segregating populations has been mostly abandoned. The association genetic approach has been used to find candidate gene SNPs associated to a broad array of quantitative traits of interest (wood properties, growth, abiotic stresses and disease resistance). However, like QTL mapping before, individual SNP x trait associations only account for a small proportion of the variation (generally less than 2-3% of the total phenotypic variance) and the total variation explained by all markers is generally less than 50%. In human genetics, this situation is called the “missing heritability” and there has been great debate over whether this problem can ever be solved in complex trait dissection in humans. In a few agricultural systems however, notably dairy cattle, researchers are now accounting for nearly all the heritable variation. Efforts to realize genomics-based breeding in conifer tree improvement in the US have culminated under a collaborative research project funded by the USDA. The Conifer Translational Genomics Network Coordinated Agricultural Project (CTGN CAP) has successfully brought genomics-based breeding to application in the four major cooperative forest tree breeding programs in the US. The project has completed the basic research on allele discovery of economic traits in conifers, conducted the translational research, and provided education and training to tree breeders to realize this goal during the four-year project period (2007 to 2011). Genomics-based breeding can now be applied to the production of over 1.3 billion loblolly pine, slash pine and Douglas-fir seedlings planted annually in the US. The CTGN CAP obtained high-density single nucleotide polymorphic (SNP) genotypes (over 7000 SNPs) on nearly 10,000 loblolly pine, slash pine, and Douglas-fir trees from the breeding cooperatives. These data were used to estimate molecular breeding values that can now be used to make selections as an alternative to breeding values based on mature traits that can take many years to the time of evaluation and can be expensive to measure in field tests. The CTGN CAP was the first to apply the advanced Illumina Infininium SNP-genotyping technology that is now being used in the breeding of most major crops such as corn, wheat, tomato, potato, and many more. The CTGN CAP culminates a long-term investment by the USDA in this team of researchers and their work on the technological advancement of tree breeding in the US. USDA’s efforts began more than 20 years ago with funding of a series of grants under the National Research Initiative Plant Genome Program and continued under the CSREES IFAFS and AFRI programs. Recently, NIFA has awarded a grant to members of this team to conduct full genome sequencing in loblolly pine, sugar pine, and Douglas-fir. The full genome sequence will soon allow tree breeders to practice genomics-based breeding using genetic variation from the entire genome (genomic selection), and thus minimizing or even eliminating the missing heritability problem in forest trees. The partnership between USDA research programs and this team of researchers has resulted in a modernization of tree breeding technology in the US that will secure US competitiveness in the production of forest products.

Molecular Plant Breeding: Principle, Method And Application

Abstract: Molecular plant breeding: principle, method and application , Molecular plant breeding: principle, method and application , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Use of Modern Molecular Biology and Biotechnology Tools to Improve the Quality Value of Oilseed Brassicas

Abstract: Technological advancement has changed the future of plants, if we are talking about the use and applications of molecular marker systems. Different types of methods and use of molecular markers have been developed, which have geared advancements in sequencing technologies for crop improvement. These methods are now being applied to a range of crops and have good potential particularly for oilseed crops in terms of both overall food and non-food yield and the nutritional and technical quality of the oils. In this context, the targets include increasing overall oil yield and its quality, which covers a range of parameters. This chapter introduces some recent techniques in molecular markers and their recent applications in plant breeding, with special reference to oilseed brassicas. The progress made in molecular plant breeding, genomic selection and genome editing—such as marker-assisted selection, next-generation sequencing and transgenesis—has contributed to a more comprehensive understanding of molecular breeding techniques and provided deeper insights into the diversity of techniques available and, most importantly, their efficient utilization in oleiferous crops. Genotyping by sequencing and association mapping based on next-generation sequencing technologies have facilitated the identification of novel genetic markers. Use of informational RNA technology and Targeting Induced Local Lesions in Genomes (TILLING) techniques have opened the gateway for deciphering complex and unstructured populations. Remarkable progress in producing such oils in commercial crops by utilizing novel techniques has been made in recent years, with several varieties being released or at advanced stages of development.

Introduction to Classical Genetics and Plant Breeding

Abstract: During the last century genetics has played a pivotal role in improving our understanding of many aspects of biology. The principles underlying heredity were first established in plants and the main practical beneficiary of these discoveries was agriculture, notably plant breeding. The purpose of this chapter is to highlight some of the key concepts that lay the genetical foundations for plant breeding. The significance and power of Mendelian genetics is presented as a fundamental foundation for plant breeding. In addition, the relationship between Mendelian genetics and the biometrical approach to continuous variation is explored from the perspective of providing a genetical foundation for manipulating quantitative traits in breeding programmes. The genetical principles of plant breeding are described in relation to the species breeding system. The application of genetic marker technology to enhance the efficiency of plant breeding is considered. The advent of DNA technology to improve the speed, precision and scale of plant breeding is outlined. Keywords: Mendelian; continuous variation; inbreeders; outbreeders; mutation; polymorphic; mapping; population

Method for cultivating rice breeding material with broad spectrum and lasting spike blast resistance

Abstract: The invention discloses a method for cultivating a breeding material with broad spectrum and lasting spike blast resistance, belonging to the technical field of rice molecular breeding. The method is characterized in that with a parent of conventional rice or hybrid rice with large production extension area and excellent comprehensive characters as a recurrent parent, broad-spectrum anti-disease genes, Pigm and Pi54, are polymerized in the breeding material through continuous backcross and convergent cross and with combination of marker-assisted selection; meanwhile, representative strains are selected for performing artificial inoculation identification of spike blast, natural inducedidentification in rice blast serious areas and basic agronomic character evaluation during a total growth period, and an advanced line with excellent spike blast resistance is obtained. The agronomic characters of the advanced line bred through the method are similar to or consistent with those of the recurrent parent, and the broad spectrum and lasting resistance to spike blast is enhanced obviously.