Stem rust is one of the major diseases of wheat round the world. New stem rust race; Ug99 and its variants as well as local stem rust races pose serious threat to wheat production in Pakistan. Stem rust can be controlled by identifying and incorporating resistant genes against the prevalent races into adapted wheat varieties. This study includes screening of 119 Pakistani wheat varieties with 18 DNA markers to detect the presence of various SR genes. Stem rust resistance genes Sr22, Sr24, Sr25 and Sr26 were absent in all varieties, whereas Sr2, Sr6, Sr9a, Sr31, Sr38 were present in various frequencies. However, frequency of APR gene Sr2 was quiet high. Results showed that Pakistani varieties are being protected by a few resistance genes and also lack potential resistance genes effective against new stem rust races. Thus, there is a need to incorporate stem rust resistance genes Sr22, Sr24, Sr25 and Sr26 into Pakistani wheat varieties, especially those possessing only Sr31. More reliable and efficient marker needs to be developed for Sr2 to assist MAS of this gene. Results of this study will help in pyramiding of SR genes in future wheat varieties to achieve durable rust resistance.
Stem rust of wheat is one of the major biotic constraints of wheat production in Ethiopia. The evolution of UG99 has become a global threat and Ethiopia is most vulnerable. The current study was conducted to identify sources of stem rust resistance in wheat. At Debre Zeit, two sets of experiments comprising 23 bread wheat and 14 durum wheat cultivars including check cultivars were exposed to artificial stem rust epidemics. A simple lattice design with two replications was used for experiment. Each block was separated from the other by spreader rows composed of PBW343 and Morocco in a 3:1 ratio. Artificial epidemics were created by inoculating the spreader rows with Sr31 virulent stem rust isolate using a syringe three times starting from stem elongation. Seven day old seedlings of wheat were also inoculated with pure ‘PBW343'' isolate maintained in the greenhouse for seedling tests. In the seedling stage, most of the durum wheat cultivars and few of the bread wheat cultivars were resistant. Most bread wheat cultivars were susceptible but the durum cultivars had adequate level of resistance. The resistant cultivars and landraces could be exploited in breeding program.
Wheat stem rust also called black stem rust caused by Puccinia graminis f. sp. tritici is amongst the biotic catastrophic diseases because of its ability to cause complete annihilation of wheat crops over wide areas during epidemic years. The East African highlands in general and Ethiopia in particular is considered as a hot spot area for the development of stem rust complex. The high virulence diversity and evolution rate of the pathogen (like race Ug99) makes a considerable proportion wheat germplasm at risk. This book provides an overview of the significance of wheat stem rust, the virulence diversity and race distribution of the pathogen and its methodological race analysis. Moreover, it entails which resistance genes are effective against the identified races and potential varieties for their current level of resistance to the prevalent and virulent P. graminis f. sp. tritici races. This book is intended for use by field worker engaged in agriculture, plant pathologist, plant breeders, genetics or biotechnology, agricultural research institutions, higher learning institutions (like Universities and colleges) and others engaged in agricultural development.
Virulence presence for stripe rust is a lingering threat to national wheat production that also extends across all geographical boundaries. The dynamics of this pathogen’s character imposes a major stress that can jeopardize wheat crops productivity. Thus breeders continue their search for new genes or assemble gene combinations that can give a genetically durable varietal performance system. Search for new gene sources is spread across the three wheat gene pools and of these a focus on the primary gene pool holds priority. in the present study germplasm from various sources was screened for stripe rust resistance.
This is a reference book which describes importance, use and basic information relevant to Wheat and its improvement. In reference to genetic diversity analysis, data was collected for yield and its components and utilized for genetic evaluation of diverse wheat genotypes. The analysis revealed high significant genetic variation for most of the yield components. Recent research findings in wheat improvement aspects have been incorporated in the book. The present research would be fruitful during formulating breeding strategies for wheat improvement. Methodology, experimental findings and their relation with earlier researches has been elaborated in the book. Thousand grain weight, plot yield, grains per spike, tiller per meter and ear length are found key traits for genetic evaluation of wheat genotypes and should be utilized in wheat breeding programmes. Genetic diversity analysis using Cluster and principal component analysis has explored an opportunity to identify diversified genotypes for crop improvement.Present book is basically written for Plant Breeding Scholar and persons interested in Wheat research.
Twenty five wheat varieties were evaluated for morphological parameters viz:Flag leaf area, Plant height, peduncle length, tillers per plant, number of nodes per plant, Spike length, awn length, number of spikelets per spike, number of grains per spike, yield per plant, harvest index, 1000-grain weight. Analysis of Variance, Least significance test and Correlation between these traits were determined.These varieties were also evaluated for the presence or absence of Lr10 and Lr34 genes.. Both Lr10 and Lr34 genes are present in genotypes ZA-77, Khyber-79 and Rohtas-90. So these varieties can be cross with other wheat varieties that lack such genes and their genetic diversity can be increased.
Ethiopia is known to be the center of diversity for durum wheat. The long co-existence between the pathogen (stem rust) and the host had enabled the evolution of various pathological races. Due to this Ethiopia is considered as a hot spot for stem rust. The races that prevail around Debre Zeit are categorized as the most virulent in the world and the area is one of the international testing site for evaluation of resistance to the pathogen. The study was conducted to identify durum wheat lines with slow rusting resistance, agronomic superiority and to understand associations among yield, yield related traits and characteristics of slow rusting resistance. The finding generally indicated specific characters to identify genotypes with slow rusting resistance and better yield. This result is useful for researchers engaged in improvement of durum wheat and especially for those interested in stem rust.
view of the immense importance of yellow rust in Pakistan, as well as at the regional and international levels, a comprehensive analysis of both aspects of Puccinia striiformis f. sp. tritici and wheat resistance were needed and is the primary objective of this book. The current information about recent yellow rust populations in Pakistan compared with Nepal were also connected to information of rust populations in other regions of the world. Information on virulences and their distribution and frequency is very useful for breeding programs to develop wheat cultivars with effective resistance. The resistance genes identified in the wheat materials through gene postulation and molecular markers, especially those with adult-plant resistance, will be useful for breeding wheat cultivars with durable resistance.
Stem rust caused by the fungus Puccinia graminis f. sp. tritici is one of the most destructive diseases of wheat. It has been a potential threat to the world food supply. It was the most threatening disease in many wheat-growing regions of the world. This is mainly because stem rust can reduce an evidently healthy stand to a broken stems and shrivelled grains within a few weeks. Although the widespread use of resistant and early maturing cultivars worldwide has reduced the disease to a less significant level, the disease continues to be a potential devastating factor to wheat production in eastern Africa. With the evolution of highly virulent race referred to as Ug99 or TTKSK, it regained its importance to treat global wheat production. There should therefore be a continuous effort to study its epidemiology and develop proper management options for a particular area. This book presents the temporal progression of stem rust as affected by various treatments, its effect on yield, yield components and quality parameters of common wheat. It is a valuable reference for researchers, development workers, graduate and undergraduate students
This study was designed due to the immense importance of wheat stripe rust in Pakistan. Considerable stripe rust with diversity among tested varieties for both adult plant resistance parameters and agronomic traits were registered. Based on overall traits, Kohsar-93, Bakhtawar-93, Saleem-2000, Fakhre-Sarhad, Tatara, Frontana and Karwan were considered suitable varieties with better level of cumulative adult plant resistance across NWFP, Pakistan. These may be recommended for cultivation and could be used in different breeding programmes in Pakistan. However, studies carried out under controlled environment with pure race culture along with molecular markers may be even more valid in elucidating the genetic mechanism of stripe ruts resistance these varieties.
In this study, Synthetic Hexaploid lines of Wheat viz., Syn 4, Syn 55 and Syn 86 were screened for resistance against virulence stem rust pathotype 40A at Division of Genetics, IARI, New Delhi. The nature of inheritance of gene governing the resistance in these synthetic lines and their allelic relationship were studied. The gene for resistance in Syn 4 and Syn 55 was found to be same, as confirmed by the test of allelism. In Syn 86. The resistance to stem rust was governed by two genes one dominant and one recessive). The F2 population developed from a cross between Syn 4 x Agra local, was used to identify molecular marker linked to stem rust resistance gene. A total of 75 RAPD’s and 35 SSR primer pair were selected covering D-Genome and B-Genome on the basis of chromosomal location of resistance gene. The SSR marker Xgwm533 was found to be linked with resistance gene at a distance of 5cM and marker Xgwm389 was co-segregating. Xgwm533 was taken from B-Genome hence, the resistance gene to be located on 3-B Genome of wheat. The use of these markers in combination with other marker could better predict the presence of gene for resistance to stem rust in breeding population.
Proliferative Kidney Disease (PKD) caused by the Malacosporean parasite Tetracapsuloides bryosalmonae, is the most economically damaging disease of British rainbow trout farming, costing the industry in excess of ?2.5 million per annum. With no vaccine or prophylactic treatment available, and only management techniques currently adopted to minimise the stress and mortality associated with the disease, the research undertaken within this book addresses a potential alternative approach; selective breeding. The book will explain the investigation undertaken to identify that selective breeding for PKD resistance is possible, and how the level of additive genetic variation was calculated, allowing estimates of heritability to be documented for commercial strains of rainbow trout (Oncorhynchus mykiss).
In view of the immense importance of yellow rust in Pakistan, as well as at the regional level, information on both aspects of Puccinia striiformis f. sp. tritici virulences and wheat resistance were needed and is the primary objective of this book. Information on novel sources of resistance, virulences and their distribution are very useful for breeding programs to develop wheat cultivars with effective resistance.
Stripe rust is an important foliar disease of Wheat in different wheat growing areas in Pakistan. Different protective measures such as fungicides, cultural or agronomic practices do not ensure long- lasting control.Genetic resistance is preferred over other strategies.Of the genetic resistance, durable resistance (race-nonspecific) is considered a sustainable measure globally. Our study included seedling testing, field evaluation, morphological marker studies and marker assisted selection.Study revealed that 4% varieties were resistant at seedling stage while rest were susceptible or intermediate.Field testing revealed that 4%varieties were resistant,70% were intermediate or moderately resistant while others were highly susceptible.For further validation,morphological markers were also observed in varieties indicating presence of gene Yr18/Lr34. Marker assisted selection of varieties revealed that 11 varieties possessed the desirable marker.Same varieties showed susceptibility at seedling stage and resistance to moderate resistance at adult stage under field conditions with either presence or absence of Leaf tip necrosis as a morphological marker.
The genus Triticum includes bread (Triticum aestivum) and durum wheat (Triticum durum) and constitutes a major source for human food consumption. Drought is currently the leading threat on world's food supply, limiting crop yield, and is complicated since drought tolerance is a quantitative trait with a complex phenotype affected by the plant's developmental stage. Drought tolerance is crucial to stabilize and increase food production since domestication has limited the genetic diversity of crops including wild wheat, leading to cultivated species, adapted to artificial environments, and lost tolerance to drought stress.