Author: Belayneh Admassu
Publisher:
ISBN: 9783869552934
Category :
Languages : en
Pages : 99

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Book Description

Author: Belayneh Admassu Yimer
Publisher: Cuvillier Verlag
ISBN: 3736932936
Category : Science
Languages : en
Pages : 110

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Book Description
As a result of a recent spread of a new and highly virulent race of Puccinia graminis f. sp. tritici called Ug99, stem rust is becoming a serious threat to wheat production in Ethiopia and other east African countries. Therefore, there is an urgent need to analyse the virulence spectrum of Pgt populations in Ethiopia. Wheat stem rust samples were collected in 2006 and 2007 in Arsi, Bale, Shewa and the Northwest regions of Ethiopia to determine the virulence diversity and race distribution in P. graminis f. sp. tritici populations. Stem rust incidence was high in Arsi, Bale and East Shewa. In Northwest Ethiopia, and North and West Shewa, stem rust was prevalent at low levels. A total of 152 isolates was analyzed and 22 races were identified. Races TTKSR (Ug99), TTHSR and RRTTR were predominant with frequencies of 26.6, 17.7 and 11.1%, respectively. These races were also detected in all regions. It turned out that the highly virulent race designated as Ug99 was present throughout the country and dominated in all regions except Northwest Ethiopia. A variant of Ug99, which is virulent against Sr24 was not detected in this study. Four stem rust resistance genes (Sr13, Sr30, Sr36 and SrTmp) were found to confer resistance to most of the races prevalent in Ethiopia. With the exception of Sr30, which is not effective to Ug99, the other three genes can be used in breeding for resistance to stem rust in Ethiopia.

Author: Jemanesh Kifetew Haile
Publisher: Cuvillier Verlag
ISBN: 3736943253
Category : Science
Languages : en
Pages : 134

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Book Description
Ethiopia is the second largest wheat producer in the sub-Saharan Africa. The country is rich in genetic resources of tetraploid wheat and has suitable environments for wheat production. However, the country is a net importer of wheat particularly durum wheat (hard wheat). The demand for durum wheat is continuously increasing because of the new emerging food processing industries. But the productivity of wheat in Ethiopia is low due to biotic and abiotic stresses. Among the biotic factors, diseases particularly stem rust play a significant role in yield reduction. As a result of a recent spread of a new and highly virulent race of Puccinia graminis f. sp. tritici (Pgt), Ug99, stem rust is becoming a serious threat to wheat production in Ethiopia as well as in other East African and wheat producing countries. Therefore, it is important to identify new resistance sources and to apply marker assisted selection for sustainable and efficient control stem rust. The aims of the studies included in this thesis were (i) identification of QTL and test for epistatic effects in a segregating population for resistance to stem rust, (ii) identification of stem rust resistance (Sr) genes that are present in durum wheat (Triticum durum Desf.) varieties that were released in Ethiopia during the period 1966–2009 and tetraploid wheat landraces using linked/diagnostic molecular markers and (iii) Evaluation of genetic diversity and relationship pattern within and among these tetraploid wheat landraces and improved varieties based on SSR/STS markers including those linked with reported stem rust resistance genes and QTL. Across all the three experiments, our study demonstrates that there exist potential germplasm and strategies to combat the threat posed by Ug99 and its derivatives. These results provide useful information to wheat breeders in Ethiopia and other national and international programs, regarding the use of available landraces and released varieties for the enhancement of the genetic base of wheat germplsm. Particularly it will give an alarm for Ethiopian wheat breeders to broaden the genetic base of the varieties that will be released in the future since most of the varieties released for the last five decades have a narrow genetic base. In addition, our research provides a base of knowledge for future QTL and gene mapping conferring resistance to stem rust and the use of the linked markers in marker assisted selection.

Author: Alan P. Roelfs
Publisher: CIMMYT
ISBN: 9789686127478
Category : Technology & Engineering
Languages : en
Pages : 92

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Author: Sewalem Amogne Mebrate
Publisher: Cuvillier Verlag
ISBN: 3867279829
Category :
Languages : en
Pages : 96

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Author: William Rodgers Bushnell
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 576

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Book Description
Origins, specificity, structure, and physiology; Evolution at the center of origin; Taxonomy of the cereal rust fungi; Specificity; The formae speciales; Race specificity and methods of study; Genetics of the pathogen: host association; Histology and molecular biology of host: parasite; Virulence frequency dynamics of cereal rust fungi; The rust fungus; Controlled infection by Puccinia graminis f.sp. tritici under artificial conditions; Developmental ultrastructure of hyphae and spores; Development and physical of teliospores; Obligate parasitism and axenic culture; The host parsite interface; The rusted host; Effects of rust on plant development in relation to the translocation of inorganic and organic solutes.

Author: P. Narayanasamy
Publisher: CRC Press
ISBN: 1040094848
Category : Science
Languages : en
Pages : 595

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Book Description
This book provides comprehensive knowledge of the methods of detection and identification of phyllosphere microbial pathogens and the management of different kinds of diseases caused by them in various crops. Interactions between pathogens and host plants result in the induction of defense responses expressed via molecular signals, from initiation of infection to systemic progression of pathogen invasion in susceptible plants and contrasting signals in resistant plants, leading to inhibition of pathogen development through activation of preinfectional and postinfectional defense responses. These are critically discussed. The author describes the intricate and complex competitive activities of the pathogens and host plants in a molecular warfare that the host plant must win to break the link in the pathogens' life cycle, allowing the development of disease management strategies based on the principles of exclusion, eradication, and immunization. Integration of strategies concerning the development of cultivars resistant to pathogens through breeding and biotechnological techniques, application of biotic and abiotic inducers of resistance to pathogens, and use of disease-free seeds and propagules that are complementary to each other along with effective cultural practices are emphasized. This book presents information gathered through an extensive literature search to help researchers and graduate students in agricultural sciences identify research gaps and successfully complete their research projects.

Author: Mahesh Rao
Publisher: Frontiers Media SA
ISBN: 2832549632
Category : Science
Languages : en
Pages : 197

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Book Description
Crop Wild Relatives (CWRs) are a key asset for agrobiodiversity, sustainable agriculture and food security overall. CRWs might contain genes for useful traits such as nutritional quality, resistance to pests and diseases, resource efficiency, and adaptability to extreme weather conditions. Their inherent genetic diversity together with the associated diversity of microbiota is a vast resource for developing more productive, nutritious, and resilient crop varieties and for diversifying farming systems. Despite their value, a wide range of CWRs are threatened and face pressures, e.g., from intensive agriculture, urbanization, pollution, and the effects of climate change. At the same time, their conservation and deployment in breeding remain still scarce. As a consequence, knowledge is lacking about the diversity that exists and precisely how that diversity may be used for crop improvement and in farming.

Author: Jon Michael Prescott
Publisher:
ISBN:
Category : Puccinia graminis
Languages : en
Pages : 158

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Book Description

Author: Matthew P. Reynolds
Publisher: Springer Nature
ISBN: 3030906736
Category : Agricultural genome mapping
Languages : en
Pages : 660

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Book Description
This open-access textbook provides a comprehensive, up-to-date guide for students and practitioners wishing to access in a single volume the key disciplines and principles of wheat breeding. Wheat is a cornerstone of food security: it is the most widely grown of any crop and provides 20% of all human calories and protein. The authorship of this book includes world class researchers and breeders whose expertise spans cutting-edge academic science all the way to impacts in farmers' fields. The book's themes and authors were selected to provide a didactic work that considers the background to wheat improvement, current mainstream breeding approaches, and translational research and avant garde technologies that enable new breakthroughs in science to impact productivity. While the volume provides an overview for professionals interested in wheat, many of the ideas and methods presented are equally relevant to small grain cereals and crop improvement in general. The book is affordable, and because it is open access, can be readily shared and translated -- in whole or in part -- to university classes, members of breeding teams (from directors to technicians), conference participants, extension agents and farmers. Given the challenges currently faced by academia, industry and national wheat programs to produce higher crop yields -- often with less inputs and under increasingly harsher climates -- this volume is a timely addition to their toolkit.