Genetic Diversity and Genome Wide Mapping of Stress Induced Secondary Metabolites in Sorghum (Sorghum Bicolor (L.) Moench).

Genetic Diversity and Genome Wide Mapping of Stress Induced Secondary Metabolites in Sorghum (Sorghum Bicolor (L.) Moench).
Author: Dinakaran Elango
Publisher:
Total Pages:
Release: 2018
Genre:
ISBN:

DM yield and forage quality parameters were measured for each treatment. We observed significant varietal differences for all the parameters except neutral detergent fiber digestibility (NDFD) in 2015. The early maturity line, AF7202, had higher yields, higher starch and net energy for lactation (NEL) levels than AF7401. The dwarf line, AF7401, had higher crude protein (CP) and NDFD than AF7202. AF7202 was more responsive to the higher N rate than AF7401. CP was increased with increased N for both varieties. Other forage quality traits were unaffected by N rates. Neither variety responded to an increase in seeding rate. This study showed that the earlier brachytic dwarf forage sorghums such as AF7202, managed with recommended seeding rates and possibly higher N rates have good potential for high forage yield and quality in central PA.

Sorghum Molecular Breeding

Sorghum Molecular Breeding
Author: R. Madhusudhana
Publisher: Springer
Total Pages: 231
Release: 2015-08-20
Genre: Technology & Engineering
ISBN: 8132224221

This book provides an up-to-date overview of international research work on sorghum. Its comprehensive coverage of our current understanding of transgenic development in sorghum and the strategies that are being applied in molecular breeding make this book unique. Important areas such as genetic diversity, QTL mapping, heterosis prediction, genomic and bioinformatics resources, post-genome sequencing developments, molecular markers development using bioinformatics tools, genetic transformation and transgenic research are also addressed. The availability of the genome sequence along with other recent developments in sequencing and genotyping technologies has resulted in considerable advances in the area of sorghum genomics. These in turn have led to the generation of a large number of DNA-based markers and resulted in the identification and fine mapping of QTL associated with grain yield, its component traits, biotic and abiotic stress tolerance as well as grain quality traits in sorghum. Though a large volume of information has accumulated over the years, especially following the sequencing of the sorghum genome, until now it was not available in a single reference resource. This book fills that gap by documenting advances in the genomics and transgenic research in sorghum and presenting critical reviews and future prospects. “Sorghum Molecular Breeding” is an essential guide for students, researchers and managers who are involved in the area of molecular breeding and transgenic research in sorghum and plant biologists in general.

Genetics, Genomics and Breeding of Sorghum

Genetics, Genomics and Breeding of Sorghum
Author: Yi-Hong Wang
Publisher: CRC Press
Total Pages: 368
Release: 2014-07-08
Genre: Science
ISBN: 1482210088

Sorghum is one of the hardiest crop plants in modern agriculture and also one of the most versatile. Its seeds provide calorie for food and feed, stalks for building and industrial materials and its juice for syrup. This book provides an in-depth review of the cutting-edge knowledge in sorghum genetics and its applications in sorghum breeding. Each chapter is authored by specialists in their fields to report the latest trends and findings. The book showcases the definitive value of sorghum as a model system to study the genetic basis of crop productivity and stress tolerance and will provide a foundation for future studies in sorghum genetics, genomics, and breeding.

The Sorghum Genome

The Sorghum Genome
Author: Sujay Rakshit
Publisher: Springer
Total Pages: 289
Release: 2017-01-18
Genre: Science
ISBN: 3319477897

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.

Diversity, Genetics, and Health Benefits of Sorghum Grain

Diversity, Genetics, and Health Benefits of Sorghum Grain
Author: Davina Rhodes
Publisher:
Total Pages: 167
Release: 2014
Genre: Anti-inflammatory agents
ISBN:

Staple cereal crops provide the majority of nutrients to the world's population, and thus, can significantly impact human nutrition and health. Phenotypic and genetic diversity within a crop can be useful for biofortification and crop improvement, but quantitative phenotyping is needed to identify varieties with high or low concentrations of a nutrient of interest, and to identify alleles responsible for quantitative trait variation of the nutrient. Sorghum (Sorghum bicolor (L.) Moench) is a diverse and widely adapted cereal crop that provides food for more than 500 million people in sub-Saharan Africa and Asia, and is becoming increasingly popular in specialty grain products in the United States. Sorghum is a valuable resource for nutrient diversity, as adaptation to different environments has led to extensive phenotypic and genetic diversity in the crop. Many sorghum varieties are rich in flavonoids, primarily 3-deoxyanthocyanidins and proanthocyanidins, which appear to protect against chronic inflammatory diseases. Most studies have only explored the health benefits of a small number of sorghum accessions, but over 45,000 sorghum accessions exist in crop gene banks. A large genetically diverse sorghum panel can be used to identify varieties with high concentrations of flavonoids and to explore the effects of natural variation of sorghum flavonoids on inflammation. This same resource can also be used to identify varieties with high concentrations of protein, fat, or starch, which can lead to improved nutritional value of sorghum grain. The overall aim of my dissertation project was to quantify sorghum flavonoids and identify allelic variants controlling them; quantify grain composition more broadly (protein, fat, and starch) and identify allelic variants controlling them; and investigate anti-inflammatory properties of sorghum extracts with contrasting levels of flavonoids. Using a large germplasm resource (USDA National Plant Germplasm System), highthroughput methods of phenotyping (near-infrared spectroscopy) and genotyping (genotyping-by-sequencing), association mapping (genome-wide association studies), and in vitro inflammation models, the work presented here provides new insights into the diversity, genetics, and anti-inflammatory properties of sorghum nutrients that are important to human health. It provides a survey of grain nutrient diversity in a large global panel of sorghum, identifies quantitative trait loci and candidate genes for underlying controls of these nutrients, and demonstrates that a larger variety of sorghum accessions than previously thought have anti-inflammatory properties.

Agronomic, Genetic and Genomic Approaches for Predicting Heterosis in Sorghum [Sorghum Bicolor (L.) Moench]

Agronomic, Genetic and Genomic Approaches for Predicting Heterosis in Sorghum [Sorghum Bicolor (L.) Moench]
Author: Frank Maulana
Publisher:
Total Pages:
Release: 2016
Genre:
ISBN:

The approach used to identify inbred lines that can produce superior hybrids is costly and time-consuming. It requires creation of all possible crosses and evaluation of the crosses to estimate combining abilities for the desired traits. Predicting heterosis or hybrid performance in any way possible may help to reduce the number of crosses to be made and evaluated. In this study, four sets of experiments were conducted to determine whether heterosis can be predicted based on inbred line performance, genetic distance between parents and genomic prediction model. The first experiment was aimed at assessing the levels of genetic diversity, population structure and linkage disequilibrium (LD) in 279 public sorghum inbred lines, based on 66,265 SNPs generated using the genotyping-by-sequencing (GBS) platform. The inbred lines were developed at different times over the last two decades and harbor robust diversity in pedigree and agronomic characteristics. Some of the inbreds are resistant to Acetolactate synthase (ALS) and Acetyl co-enzyme-A carboxylase (ACC) inhibitor herbicides. The mean polymorphic information content (PIC) and gene diversity across the entire inbreds were 0.35 and 0.46, respectively with non-herbicide resistant inbreds harboring more diversity than the herbicide resistant ones. The population structure analysis clustered the inbred lines into three major subgroups according to pedigree and fertility-reaction with the maintainer lines (B-lines) distinctly forming a separate cluster. Analysis of molecular variance (AMOVA) revealed more variation within subgroups than among subgroups. Substantial linkage disequilibrium (LD) was detected between the markers in the population with marked variation between chromosomes. This information may facilitate the use of the inbreds in sorghum breeding programs and provide perspectives for optimizing marker density for gene mapping and marker-assisted breeding. The second experiment, based on 102 F1 hybrids developed by intercrossing closely and distantly related inbreds, was conducted to investigate the relationship of genetic distance between parents with hybrid vigor or heterosis. The F1 hybrids alongside their parents were evaluated at two environments in a randomized complete block design with three replications. The results show that correlations of genetic distance between parents with hybrid performance and heterosis were variable and dependent on the trait. Though most were statistically non-significant and not strong to be used as predictor for heterosis, the results tend to show that certain level of genetic distance between parents is needed to capture maximum heterosis and hybrid performance. The objective of the third research study was to determine whether traits measured on parents can be used to predict hybrid performance in sorghum and to assess the combining ability of selected inbreds. Forty-six parental inbred lines and 75 F1 hybrids generated from intercrossing the inbreds were evaluated in four environments in a randomized complete block design with three replications. The average performance of the parents (mid-parent) was significantly correlated with hybrid performance for thousand kernel weight, days to flowering and plant height. Significant general (GCA) and specific (SCA) combining abilities were observed for most traits, with highly significant GCA effects observed for most traits as compared to SCA indicating that additive genetic effects are more important in affecting the inheritance of the traits measured. Results show that studying parental inbred line performance could generate important information for predicting hybrid performance in sorghum. The fourth experiment was aimed at assessing the efficacy of genomic prediction of hybrid performance in sorghum. Genomic prediction was performed with five-fold cross-validation procedure on 204 F1 hybrids developed using 102 inbred lines. A total of 66,265 SNP markers generated using genotyping-by-sequencing were used in this study. Results showed that increasing training population size increased prediction accuracies for all traits with the effect being different for different traits. Also, considering additive effects alone versus additive and dominance effects in the model showed similar trend of prediction accuracy but the full model (considering both additive and dominance effects of the markers) provided better prediction at least for some of the traits. The results suggest that genomic prediction could become an effective tool for predicting the performance of untested sorghum hybrids thus adding efficiency to hybrid selection.

Genetic Diversity and Evolution of Disease Response Genes in Sorghum Bicolor L. Moench and Other Cereals

Genetic Diversity and Evolution of Disease Response Genes in Sorghum Bicolor L. Moench and Other Cereals
Author: Alejandro Zamora-Melendez
Publisher:
Total Pages: 0
Release: 2010
Genre:
ISBN:

Several studies have shown that disease resistance genes diverge under recurrent positive selection as a result of a molecular arms-race between hosts and pathogens. However, these studies have been conducted mainly in animals and few plant genes have been shown to evolve adaptively. The study of plant molecular adaptation for disease resistance is fundamental to our understanding of plant-microbe interactions and to the development of novel plant breeding strategies. Here, we combined information from the expression pattern of Sorghum bicolor genes and their divergence to rice in order to identify candidate disease response genes (DRGs). We used evolutionary analyses of orthologous DRG sets from grass species to identify positively selected genes and the targeted residues. Six genes showed a pattern of substitution consistent with positive selection: a thaumatin, a peroxidase and a barley mlo homolog, all known antifungal proteins; and a MADS box gene, an eIF5 gene and a gene of unknown function: SESPY. All adaptive sites mapped to the surface of the crystal structures of peroxidase and thaumatin and several are close to the active sites. This information provides a basis for functional validation studies, the identification of accessions having variation at important residues and the rational design of DRGs. Rapid divergence through positive selection should correlate to reduced intraspecific polymorphism. Here we compare the macroevolution and intraspecific polymorphism of positively selected disease response genes and show that the patterns of polymorphism found are consistent with both selective sweeps and balancing selection. The sorghum mlo homolog and SESPY, have old, divergent alleles, while a peroxidase and a gene with a RNA binding domain have significantly reduced diversity suggesting a recent selective sweep. Finally, we show that sorghum DRGs are significantly closer to the telomere and have more exons than a control set of evenly expressed genes. The evidence from gene location; structure; macro-evolution and polymorphism of these DRGs point to the great selective pressure produced by pathogens which has driven the evolution of cereal genome content, order and function.

Genomic Mapping for Grain Yield, Stay Green, and Grain Quality Traits in Sorghum

Genomic Mapping for Grain Yield, Stay Green, and Grain Quality Traits in Sorghum
Author: Sivakumar Sukumaran
Publisher:
Total Pages:
Release: 2012
Genre:
ISBN:

Knowledge of the genetic bases of grain quality traits will complement plant breeding efforts to improve the end use value of sorghum (Sorghum bicolor (L.) Moench). The objective of the first experiment was to assess marker-trait associations for 10 grain quality traits through candidate gene association mapping on a diverse panel of 300 sorghum accessions. The 10 grain quality traits were measured using the single kernel characterization system (SKCS) and near-infrared reflectance spectroscopy (NIRS). The analysis of the accessions through 1,290 genome-wide single nucleotide polymorphisms (SNPs) separated the panel into five subpopulations that corresponded to three major sorghum races (durra, kafir, and caudatum), one intermediate race (guinea-caudatum), and one working group (zerazera/caudatum). Association analysis between 333 SNPs in candidate genes/loci and grain quality traits resulted in eight significant marker-trait associations. A SNP in starch synthase IIa (SSIIa) gene was associated with kernel hardness (KH) with a likelihood ratio-based R2 (R[subscript]L[subscript]R2) value of 0.08. SNPs in starch synthase (SSIIb) gene (R[subscript]L[subscript]R2 = 0.10) and loci pSB1120 (R[subscript]L[subscript]R2 = 0.09) was associated with starch content. Sorghum is a crop well adapted to the semi arid regions of the world and my harbor genes for drought tolerance. The objective of second experiment was to identify quantitative trait loci (QTLs) for yield potential and drought tolerance. From a cross between Tx436 (food grain type) and 00MN7645 (drought tolerant) 248 recombinant inbred lines (RILs) was developed. Multi-location trials were conducted in 8 environments to evaluate agronomic performance of the RILs under favorable and drought stress conditions. The 248 RILs and their parents were genotyped by genotyping-by-sequencing (GBS). A subset of 800 SNPs was used for linkage map construction and QTL detection. Composite interval mapping identified a major QTLs for grain yield in chromosome 8 and QTL for flowering time in chromosome 9 under favorable conditions. Three major QTLs were detected for grain yield in chromosomes 1, 6, and 8 and two flowering time QTLs on chromosome 1 under drought conditions. Six QTLs were identified for stay green: two on chromosome 4; one each on chromosome 5, 6, 7, and 10 under drought conditions.

Quantitative Genomic Analysis of Agroclimatic Traits in Sorghum

Quantitative Genomic Analysis of Agroclimatic Traits in Sorghum
Author: Olalere Marcus Olatoye
Publisher:
Total Pages:
Release: 2017
Genre:
ISBN:

Climate change has been anticipated to affect agriculture, with most the profound effect in regions where low input agriculture is being practiced. Understanding of how plants evolved in adaptation to diverse climatic conditions in the presence of local stressors (biotic and abiotic) can be beneficial for improved crop adaptation and yield to ensure food security. Great genetic diversity exists for agroclimatic adaptation in sorghum (Sorghum bicolor L. Moench) but much of it has not been characterized. Thus, limiting its utilization in crop improvement. The application of next-generation sequencing has opened the plant genome for analysis to identify patterns of genome-wide nucleotide variations underlying agroclimatic adaptation. To understand the genetic basis of adaptive traits in sorghum, the genetic architecture of sorghum inflorescence traits was characterized in the first study. Phenotypic data were obtained from multi-environment experiments and used to perform joint linkage and genome-wide association mapping. Mapping results identified previously mapped and novel genetic loci underlying inflorescence morphology in sorghum. Inflorescence traits were found to be under the control of a few large and many moderate and minor effect loci. To demonstrate how our understanding of the genetic basis of adaptive traits can facilitate genomic enabled breeding, genomic prediction analysis was performed with results showing high prediction accuracies for inflorescence traits. In the second study, the sorghum-nested association mapping (NAM) population was used to characterize the genetic architecture of leaf erectness, leaf width, and stem diameter. About 2200 recombinant inbred lines were phenotyped in multiple environments. The obtained phenotypic data was used to perform joint linkage mapping using ~93,000 markers. The proportion of phenotypic variation explained by QTL and their allele frequencies were estimated. Common and moderate effects QTL were found to underlie marker-trait associations. Furthermore, identified QTL co-localized with genes involved in both vegetative and inflorescence development. Our results provide insights into the genetic basis of leaf erectness and stem diameter in sorghum. The identified QTL will also facilitate the development of genomic-enable breeding tools for crop improvement and molecular characterization of the underlying genes Finally, in a third study, 607 Nigerian accessions were genotyped and the resulting genomic data [about 190,000 single nucleotide polymorphisms (SNPs)] was used for downstream analysis. Genome-wide scans of selection and genome-wide association studies (GWAS) were performed and alongside estimates of levels of genetic differentiation and genetic diversity. Results showed that phenotypic variation in the diverse germplasm had been shaped by local adaptation across climatic gradient and can provide plant genetic resources for crop improvement.