The Genetic Basis of Response to Within-family Bidirectional Selection in Some Populations of Sorghum (Sorghum Bicolor (L.) Moench). PDF Download

Author: Thomas Clayton Ainsworth
Publisher:
ISBN:
Category :
Languages : en
Pages : 320

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Author: Alejandro Zamora-Melendez
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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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.

Author: Yi-Hong Wang
Publisher: CRC Press
ISBN: 1482210096
Category : Science
Languages : en
Pages : 366

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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

Author:
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 1244

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Author: C.P. Camargo
Publisher:
ISBN:
Category :
Languages : en
Pages : 74

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Seed of 36 sorghum (Sorghum bicolor (L.) Moench) geneotypes selected on the basis of high physiological quality were evaluated to determine genotypic differences in response to germination temperatures ranging from 10 to 42C. Seed of high, medium, and low quality were evaluated to investigate seed quality-germination-tempearture relationships. Seed of 24 genotypes were dimensionally sized and permitted to imbile water to evaluate both genotypic variation in speed of water uptake and the influence of seed size on water imbibition. Sorghum seed of near maximum phusiological quality germinated equally well at temperatures between 20 and 30C. Among the range of genotypes evaluated, constant germination temperatures of 14 and 42C were the best for screening genotypes for their to germinate at low and high temperatures, respectively. Two genotypes, IS 1166C and SC 175-14, were equal to or better than all other genotypes at all germination temperatures evaluated. Five genotypes, E 35-1, MN 1958, MN 4508, IS 12685C and TPDXB1388 (9256) were very sensitive to germination temperatures outside the optimal range. Seed of lower physilogical quality were more sensitive to germination temperatures than those of high quality. However, there was a differential response among the genotypes. Regardless of genotype, small seed increased in moisture content more rapidly than large seed when water supply was not limited. Within the same size. there was genotypic varation both in the rate of moisture absorption and the time (...).

Author: Xerox University Microfilms
Publisher:
ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 1226

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Author: Mauricio Riccelli-Mattei
Publisher:
ISBN:
Category :
Languages : en
Pages : 290

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Author: Joseph Evans
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Sorghum (Sorghum bicolor [L.] Moench) is the world's fifth most economically important cereal crop, grown worldwide as a source of food for both humans and livestock. Sorghum is a C4 grass that is well adapted to hot and arid climes and is popular for cultivation on lands of marginal quality. Recent interest in development of biofuels from lignocellulosic biomass has drawn attention to sorghum, which can be cultivated in areas not suitable for more traditional crops, and is capable of generating plant biomass in excess of 40 tons per acre. While the quantity of biomass and low water consumption make sorghum a viable candidate for biofuels growth, the biomass composition is enriched in lignin, which is problematic for enzymatic and chemical conversion techniques. The genetic basis for stem composition was analyzed in sorghum populations using a combination of genetic, genomic, and bioinformatics techniques. Utilizing acetyl bromide extraction, the variation in stem lignin content was quantified across several sorghum cultivars, confirming that lignin content varied considerably among sorghum cultivars. Previous work identifying sorghum reduced-lignin lines has involved the monolignol biosynthetic pathway; all steps in the pathway were putatively identified in the sorghum genome using sequence analysis. A bioinformatics toolkit was constructed to allow for the development of genetic markers in sorghum populations, and a database and web portal were generated to allow users to access previously developed genetic markers. Recombinant inbred lines were analyzed for stem composition using near infrared reflectance spectroscopy (NIR) and genetic maps constructed using restriction site-linked polymorphisms, revealing 34 quantitative trail loci (QTL) for stem composition variation in a BTx642 x RTx7000 population, and six QTL for stem composition variation in an SC56 x RTx7000 population. Sequencing the genome of BTx642 and RTx7000 to a depth of ~11x using Illumina sequencing revealed approximately 1.4 million single nucleotide polymorphisms (SNPs) and 1 million SNPs, respectively. These polymorphisms can be used to identify putative amino acid changes in genes within these genotypes, and can also be used for fine mapping. Plotting the density of these SNPs revealed patterns of genetic inheritance from shared ancestral lines both between the newly sequenced genotypes and relative to the reference genotype BTx623.

Author: National Agricultural Library (U.S.)
Publisher:
ISBN:
Category : Agriculture
Languages : en
Pages : 638

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Author: MALLIKARJUN H
Publisher:
ISBN:
Category :
Languages : en
Pages : 157

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