Identifying Novel Disease Resistance and Drought Tolerance Genes in a Synthetic NAM Population


Book Description

Wheat was domesticated approximately 10,000 years ago when the tetraploid grass Triticum turgidum (AABB) is thought to have hybridized with the diploid grass Aegilops tauschii Coss. (DD), resulting in hexaploid wheat Triticum aestivum (AABBDD). Most research confirms the D-genome was the last genome to be introduced, is the least diverse, and tends to have fewer known markers. This distinct lack of diversity has hindered breeders and geneticists; diversity could lead to higher yields, better end-use quality, and increased tolerance to biotic and abiotic stress. Synthetic wheat is a tool that can be used to incorporate genetic diversity and provide disease resistance genes not found in common germplasm. Synthetic wheat is made by recreating the hybridization that led to T. aestivum using different subspecies of both T. durum and Ae. tauschii. The result is a primary synthetic hexaploid wheat (AABBDD) that has diverse alleles and trait combinations, and can be readily crossed into adapted germplasm. In addition to being a source of novel disease resistance genes, synthetic wheat lines are also known to have more diverse root systems. The objective of this dissertation was to evaluate a synthetic nested association mapping population, the D-genome Nested Association Mapping Population (DNAM) for novel abiotic and biotic stress tolerance genes. Multiple projects involved screening selections of the DNAM population for resistance to stripe rust (Puccinia striiformis), Fusarium crown rot (Fusarium culmorum and Fusarium pseudograminearum), and cereal cyst nematode (Heterodera avenae and Heterodera filipjevi). One novel gene was found to confer resistance to both H. filipjevi and avenae cereal cyst nematodes. Moderate resistance to fusarium crown rot was also detected, but is contributed both from the recurrent parent of the population as well as by several A. tauschii donor parents. A subset of the DNAM was also used for a three-year, nine environment drought study. A genome-wide association study (GWAS) revealed three quantitative trait loci (QTL) for grain protein concentration and quality across all nine environments, and nine QTL contributing to those same traits within individual environments.




Genetically Engineered Crops


Book Description

Genetically engineered (GE) crops were first introduced commercially in the 1990s. After two decades of production, some groups and individuals remain critical of the technology based on their concerns about possible adverse effects on human health, the environment, and ethical considerations. At the same time, others are concerned that the technology is not reaching its potential to improve human health and the environment because of stringent regulations and reduced public funding to develop products offering more benefits to society. While the debate about these and other questions related to the genetic engineering techniques of the first 20 years goes on, emerging genetic-engineering technologies are adding new complexities to the conversation. Genetically Engineered Crops builds on previous related Academies reports published between 1987 and 2010 by undertaking a retrospective examination of the purported positive and adverse effects of GE crops and to anticipate what emerging genetic-engineering technologies hold for the future. This report indicates where there are uncertainties about the economic, agronomic, health, safety, or other impacts of GE crops and food, and makes recommendations to fill gaps in safety assessments, increase regulatory clarity, and improve innovations in and access to GE technology.







The World Wheat Book


Book Description

This work is a comprehensive history of wheat across all its main areas of production. New techniques such as in vitro culture now enable the development of a greater level of understanding of the genetics of wheat.




Rice Improvement


Book Description

This book is open access under a CC BY 4.0 license. By 2050, human population is expected to reach 9.7 billion. The demand for increased food production needs to be met from ever reducing resources of land, water and other environmental constraints. Rice remains the staple food source for a majority of the global populations, but especially in Asia where ninety percent of rice is grown and consumed. Climate change continues to impose abiotic and biotic stresses that curtail rice quality and yields. Researchers have been challenged to provide innovative solutions to maintain, or even increase, rice production. Amongst them, the ‘green super rice’ breeding strategy has been successful for leading the development and release of multiple abiotic and biotic stress tolerant rice varieties. Recent advances in plant molecular biology and biotechnologies have led to the identification of stress responsive genes and signaling pathways, which open up new paradigms to augment rice productivity. Accordingly, transcription factors, protein kinases and enzymes for generating protective metabolites and proteins all contribute to an intricate network of events that guard and maintain cellular integrity. In addition, various quantitative trait loci associated with elevated stress tolerance have been cloned, resulting in the detection of novel genes for biotic and abiotic stress resistance. Mechanistic understanding of the genetic basis of traits, such as N and P use, is allowing rice researchers to engineer nutrient-efficient rice varieties, which would result in higher yields with lower inputs. Likewise, the research in micronutrients biosynthesis opens doors to genetic engineering of metabolic pathways to enhance micronutrients production. With third generation sequencing techniques on the horizon, exciting progress can be expected to vastly improve molecular markers for gene-trait associations forecast with increasing accuracy. This book emphasizes on the areas of rice science that attempt to overcome the foremost limitations in rice production. Our intention is to highlight research advances in the fields of physiology, molecular breeding and genetics, with a special focus on increasing productivity, improving biotic and abiotic stress tolerance and nutritional quality of rice.




Biotic and Abiotic Stress Tolerance in Plants


Book Description

This book highlights some of the most important biochemical, physiological and molecular aspects of plant stress, together with the latest updates. It is divided into 14 chapters, written by eminent experts from around the globe and highlighting the effects of plant stress (biotic and abiotic) on the photosynthetic apparatus, metabolites, programmed cell death, germination etc. In turn, the role of beneficial elements, glutathione-S-transferase, phosphite and nitric oxide in the adaptive response of plants under stress and as a stimulator of better plant performance is also discussed. A dedicated chapter addresses research advances in connection with Capsicum, a commercially important plant, and stress tolerance, from classical breeding to the recent use of large-scale transcriptome and genome sequencing technologies. The book also explores the significance of the liliputians of the plant kingdom (Bryophytes) as biomonitors/bioindicators, and general and specialized bioinformatics resources that can benefit anyone working in the field of plant stress biology. Given the information compiled here, the book will offer a valuable guide for students and researchers of plant molecular biology and stress physiology alike.




Broadening the Genetic Base of Grain Cereals


Book Description

This book offers comprehensive coverage of important grain cereals including their origin and distribution, crop gene pool, level of diversity, production constraints, traits of importance for genetic base widening, crop improvement methodologies, genome mapping, genomics for breeding, and future strategies. The chapters, contributed by eminent crop researchers from around the world, provide rare insights into the crop-specific constraints and prospects drawing from their substantial experience. As such, the book offers an essential source of information for grain cereals scientists, teachers, students, policy planners and developmental experts alike. Grain cereals, which comprise rice, wheat, maize, barley, oats, sorghum and millets, are members of the grass family. These crops are vital to human nutrition, thanks to their roles as staple food crops in different parts of the globe. Some of them are rich sources of carbohydrates, which provide energy, while others are important sources of minerals, vitamins and proteins, in addition to their medicinal properties. In most cereals, the existing variability among elite germplasm has been exploited to attain a desirable level of productivity. However, to make further breakthroughs in enhancing yield and improving stability in future crop cultivars, new sources of genes/alleles need to be identified in wild/weedy species and incorporated into the cultivated varieties. Though there have been many publications on various aspects of grain cereal improvement in the recent past, to date this essential information has remained scattered among different periodicals.







The Sorghum Genome


Book Description

This book provides insights into the current state of sorghum genomics. It particularly focuses on the tools and strategies employed in genome sequencing and analysis, public and private genomic resources and how all this information is leading to direct outcomes for plant breeders. The advent of affordable whole genome sequencing in combination with existing cereal functional genomics data has enabled the leveraging of the significant novel diversity available in sorghum, the genome of which was fully sequenced in 2009, providing an unmatched resource for the genetic improvement of sorghum and other grass species. Cultivated grain sorghum is a food and feed cereal crop adapted to hot and dry climates, and is a staple for 500 million of the world’s poorest people. Globally, sorghum is also an important source of animal feed and forage, an emerging biofuel crop and model for C4 grasses, particularly genetically complex sugarcane.




Stress Signaling in Plants: Genomics and Proteomics Perspective, Volume 1


Book Description

Plant diseases, extreme weather caused by climate change, drought and an increase in metals in soil are amongst the major limiting factors of crop production worldwide. They devastate not only food supply but also the economy of a nation. Keeping in view of the global food scarcity, there is, an urgent need to develop crop plants with increased stress tolerance so as to meet the global food demands and to preserve the quality of our planet. In order to do this, it is necessary to understand how plants react and adapt to stress from the genomic and proteomic perspective. Plants adapt to stress conditions by activation of cascades of molecular mechanisms, which result in alterations in gene expression and synthesis of protective proteins/compounds. From the perception of the stimulus to transduction of the signal, followed by an appropriate response, the plants employ a complex network of primary and secondary messenger molecules. Cell signaling is the component of a complex system of communication that directs basic cellular activities and synchronizes cell actions. Cells exercise a large number of noticeably distinct signaling pathways to regulate their activity. In order to contend with different environmental adversities plants have developed a series of mechanisms at the physiological, cellular and molecular level. This two volume set takes an in-depth look at the Stress Signaling in Plants from a uniquely genomic and proteomics perspective. Stress Signaling in Plants offers a comprehensive treatise on the Chapter, covering all of the signaling pathways and mechanisms that have been researched so far. Each chapter provides in-depth explanation of what we currently know of a particular aspect of stress signaling and where we are headed. All authors have currently agreed and abstracts have been complied for the first volume, due out midway through 2012. We aim to have the second volume out at the beginning of 2013.​