Identification of Two Interacting Quantitative Trait Loci Controlling for Condensed Tannin in Sorghum Grain and Grain Quality Analysis of a Sorghum Diverse Collection PDF Download
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Author: Wenwen Xiang
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Languages : en
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Tannin, a second metabolic product in sorghum, has been directly related to resistance to insects and birds. Tannin also impacts sorghum nutritional value. Previous studies have shown tannin content has a positive correlation with early season cold tolerance, an important agronomic trait. Sorghum contains condensed tannins in testa layer below the pericarp. The testa layer tannin is controlled by two complementary genes B1 and B2: tannins are present when both genes are dominant but absent when only one or none of these two is dominant. The purpose of this research is to identify and map QTLs associated with the presence of condensed tannins, analyze interaction of QTLs, and provide a potential path to dissect the more complex trait of early season cold tolerance in future studies. A population of 109 F6:7 recombinant inbred lines (RILs) developed from the cross of a high tannin sorghum Shan Qui Red (SQR) and non-tannin line Tx430 was used in the mapping study. Two QTLs related to condense tannin presence in testa layer were mapped to chromosome 2 and 4, respectively. Strong epistatic interaction of these two QTLs was detected. The two QTLs together with their interaction explained 74% of the phenotypic variation. Sorghum grain quality traits, including kernel size, kernel hardness, protein and starch content, are complex traits which are directly related to sorghum nutritional value and market value. Association mapping is a promising method for complex quantitative traits analysis and dissection in plant science. Sorghum grain quality trait association analysis research is purposed to analyze large amount of grain quality data based on a diversity panel. A sorghum bicolor panel of 300 lines including germplasm derived from sorghum conversion program and elite commercial lines were established and served as diversity population for the association study. Phenotypic data of grain quality traits were collected by single kernel characterization system (SKCS) and near infrared reflectance spectroscopy (NIRS). Data analysis proved high diversity within the SB panel. A correlation between tannin presence and kernel hardness was also observed. Quality traits showed high consistence across years and environments.
Author: Wenwen Xiang
Publisher:
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Languages : en
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Book Description
Tannin, a second metabolic product in sorghum, has been directly related to resistance to insects and birds. Tannin also impacts sorghum nutritional value. Previous studies have shown tannin content has a positive correlation with early season cold tolerance, an important agronomic trait. Sorghum contains condensed tannins in testa layer below the pericarp. The testa layer tannin is controlled by two complementary genes B1 and B2: tannins are present when both genes are dominant but absent when only one or none of these two is dominant. The purpose of this research is to identify and map QTLs associated with the presence of condensed tannins, analyze interaction of QTLs, and provide a potential path to dissect the more complex trait of early season cold tolerance in future studies. A population of 109 F6:7 recombinant inbred lines (RILs) developed from the cross of a high tannin sorghum Shan Qui Red (SQR) and non-tannin line Tx430 was used in the mapping study. Two QTLs related to condense tannin presence in testa layer were mapped to chromosome 2 and 4, respectively. Strong epistatic interaction of these two QTLs was detected. The two QTLs together with their interaction explained 74% of the phenotypic variation. Sorghum grain quality traits, including kernel size, kernel hardness, protein and starch content, are complex traits which are directly related to sorghum nutritional value and market value. Association mapping is a promising method for complex quantitative traits analysis and dissection in plant science. Sorghum grain quality trait association analysis research is purposed to analyze large amount of grain quality data based on a diversity panel. A sorghum bicolor panel of 300 lines including germplasm derived from sorghum conversion program and elite commercial lines were established and served as diversity population for the association study. Phenotypic data of grain quality traits were collected by single kernel characterization system (SKCS) and near infrared reflectance spectroscopy (NIRS). Data analysis proved high diversity within the SB panel. A correlation between tannin presence and kernel hardness was also observed. Quality traits showed high consistence across years and environments.
Author: Sivakumar Sukumaran
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Languages : en
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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.
Author: Jorge Luis Moran Maradiaga
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Languages : en
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Lately the rate of genetic gain in most agronomic crop species has been reduced due to several factors that limit breeding efficiency and genetic gain. New genetic tools and more powerful statistical analyses provide an alternative approach to enhance genetic improvements through the identification of molecular markers linked to genomic regions or QTLs controlling quantitative traits. The main objective of this research was to identify genomic regions associated with enhanced agronomic performance in lines per se and hybrid combination in Sorghum bicolor (L.) Moench. A population composed of 187 F5:6 recombinant inbred lines (RIL) was derived from the cross of restorer lines RTx430 and RTx7000. Also, a testcross hybrid population (TCH) was developed by using each RIL as a pollinator onto ATx2752. A linkage map was constructed using 174 marker loci generated from AFLP and SSR primer combinations. These markers were assigned to 12 different linkage groups. The linkage map covers 1573 cM with marker loci spaced at an averaged 9.04 cM. In this study, 89 QTL that control variation in seven different morphological traits were identified in the recombinant inbred line population, while in the testcross hybrid population, 79 QTL were identified. These traits included grain yield, plant height, days to mid-anthesis, panicle number, panicle length, panicle exsertion and panicle weight. These putative QTL explained from 4 to 42% of the phenotypic variation observed for each trait. Many of the QTL were not consistent across populations and across environments. Nevertheless, a few key QTL were identified and the source of the positive additive genetics isolated. RTx7000 was consistently associated with better agronomic performance in RIL, while in testcrosses, RTx430 was. Some genomic regions from RTx7000 may be utilized to improve RTx430 as a line per se. However, it is very unlikely that such regions will have a positive effect on the combining ability of RTx430 since testcross results did not reveal any transgressive segregants from the RIL population.
Author: Adalberto Sanchez Gomez
Publisher:
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Languages : en
Pages : 186
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Author: Nicholas Ace Pugh
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Languages : en
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Popped sorghum (Sorghum bicolor, L. Moench) is becoming increasingly popular with niche consumers. However, sorghum has not undergone the years of intensive selective breeding that popcorn has. This study measured popping characteristics and grain traits to estimate heritability, the relative effect of environment and genotype x environment interactions on these traits and to identify quantitative trait loci (QTL) for popping quality. Using a heated-air popping methodology, a recombinant inbred line population was phenotyped for popping characteristics in grain from three environments in Texas. Entry-mean heritability of popping efficiency (PE) ranged from 0.595 - 0.755 and the heritability of expansion ratio (ER) ranged from 0.617 - 0.769 across environments. ANOVA indicate that both environment and genotype x environment interactions were significant sources of variation. Using genome sequence mapping technology, five QTL were identified for popping efficiency and four were identified for expansion ratio. Additionally QTL for endosperm color, kernel diameter, kernel weight, and kernel hardness were found, and several of those were consistent across multiple production environments. These results indicate that popping quality a complex quantitative trait in sorghum, but improvement of popping efficiency, expansion ratio, and other kernel characteristics via marker-assisted selection is possible. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/155661
Author: Messias Gonzaga Pereira
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Languages : en
Pages : 354
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In this investigation, restriction fragment length polymorphisms (RFLPs) were used to construct a genetic linkage map for sorghum and to map quantitative trait loci (QTL) controlling morphological characteristics. For both purposes, and F2 population from a cross between Sorghum bicolor subspecies bicolor (CK60) and Sorghum bicolor subspecies drummondii (PI229828) was used. The map consists of 201 loci distributed among ten linkage groups covering a distance of 1530 cm, with and average eight cM between adjancent loci. Maize genomic clones, maize cDNA clones, and sorghum genomic clones were used to identify the loci. Comparison of sorghum and maize maps revealed a high degree of homology, linkage order, and similar genetic distance. Most often a sorghum linkage group contains loci that map to two chromosomes. Frequently, these two maize chromosomes share considerable DNA duplication. For QTL identification, 152 unselected F2 plants were evaluated. Interval mapping identified a total of 43 QTL, four for plant height, four for tillering, three for leaf length, two for leaf width, three for stalk circumference, two for maturity, six for panicle length, five for seed-branch length, two for sterile portion of the seed-branch, six for penducle diameter, three for number of seed-branchs per panicle, and three for seed weight. For each QTL, the most likely map position, magnitude of effects, gene action, and the source (progenitor) of alleles that increased the trait mean were described. Eighty-one percent (...).
Author: Balaji Aravindhan Pandian
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Languages : en
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Grain sorghum [Sorghum bicolor (L.) Moench ssp. bicolor] is a versatile crop with multiple uses, including for food, feed, and fuel. Postemergence (POST) grass weed control continues to be a major challenge in grain sorghum, primarily due to a lack of herbicide options registered for POST use. The 4- hydroxyphenylpyruvate dioxygenase (HPPD)- (e.g., mesotrione or tembotrione) and acetolactate synthase (ALS)- inhibitor (e.g., chlorsulfuron) herbicides are used for POST control of a broad-spectrum of weeds including grasses in corn and wheat but not in sorghum, due to crop injury. The development of herbicide-resistant sorghum technology to facilitate broad-spectrum POST weed control can be an economical and viable solution. Previously we have identified four sorghum genotypes, two each resistant to mesotrione (G-1 and G-10), tembotrione (G-200 and G-350) and, one susceptible genotype (S-1) from the sorghum association panel. Further, we found that the genotype S-1 is highly resistant to chlorsulfuron. The objectives of this dissertation were to 1) investigate the inheritance, mechanism, and identify genetic loci conferring resistance to mesotrione and tembotrione, 2) characterize, and investigate the inheritance and mechanism of resistance to chlorsulfuron in grain sorghum. To understand the inheritance of the mesotrione and tembotrione resistance, F1 and F2 progeny were generated by performing crosses using S-1 and G-1, G-10, G-200, or G-350. The F1 and F2 progeny were evaluated for their response to various doses of mesotrione and tembotrione treatment. Likewise, chlorsulfuron dose-response experiments were conducted using S-1 along with BTx623, a susceptible check and also F1 and F2 progeny were generated by crossing S-1 and BTx623. The results of genetic analyses of the F1 and F2 progeny demonstrated that the mesotrione resistance in G-1 and G-10 is a single dominant trait, and while the tembotrione resistance in G-200 and G-350 is a partially dominant polygenic trait. Further, sequencing of HPPD gene, the molecular target of mesotrione and tembotrione in the resistant genotypes, revealed no mutations known to bestow resistance. Additionally, the role of cytochrome P450 (CYP) in metabolizing mesotrione and tembotrione, using CYP-inhibitors, malathion and piperonyl butoxide (PBO) was also assessed. The results indicated a significant reduction in biomass accumulation in sorghum plants pre-treated with malathion or PBO, suggesting the involvement of CYPs in the metabolism of mesotrione and tembotrione. Bulk segregation analysis combined with RNA-Seq (BSR-seq) was used to identify the genomic region associated with mesotrione resistance; however, the sequence analyses was unable to map the resistance gene within a smaller interval. Genotype-by-sequencing (GBS) based quantitative trait loci (QTL) mapping revealed three QTLs associated with tembotrione resistance in G-200. The results of the chlorsulfuron dose-response assay indicated that S-1 and F1 progeny were ~20-fold, more resistant to chlorsulfuron relative to BTx623. Segregation of F2 progeny into 3:1 (resistance: susceptibility), suggested that chlorsulfuron resistance in S-1 is a single dominant trait. Sequence analysis of the ALS gene, the molecular target of chlorsulfuron from S-1 revealed no mutations that confer resistance to chlorsulfuron; however, a significant reduction in biomass accumulation was found in plants pre-treated with malathion, indicating that the metabolism of chlorsulfuron contributes to resistance in S-1. Overall, the results of this dissertation provide opportunities to develop herbicide-resistant sorghum hybrids via introgression, which can help effective, POST weed management.
Author: Joel Ira Weller
Publisher: CABI
ISBN: 1845937341
Category : Technology & Engineering
Languages : en
Pages : 288
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Quantitative Trait Loci (QTL) is a topic of major agricultural significance for efficient livestock production. This book covers various statistical methods that have been used or proposed for detection and analysis of QTL and marker-and gene-assisted selection in animal genetics and breeding.
Author: Karen Ruth Harris
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Languages : en
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Sorghum (Sorghum bicolor [L.] Moench) is the fifth most economically important cereal grown worldwide and is a source of food, feed, fiber and fuel. Sorghum, a C4 grass and a close relative to sugarcane, is adapted to hot, dry adverse environments. Some genotypes of sorghum called stay-green have delayed leaf senescence during grain ripening under drought stress conditions which allows normal grain filling whereas most sorghum lines senesce early under post-anthesis drought. Eight sources of stay-green have been identified in the sorghum germplasm collection, most originating from Sudan and Ethiopia. The diversity of the eight sources of staygreen was analyzed using 55 simple sequence repeats (SSR) markers with genome coverage. This analysis showed that the sources of stay-green are quite diverse and can be divided into five groups based on race or working group. Three sources of stay-green have been used to identify 12 major quantitative trait loci (QTL) that modulate this trait. The origin of favorable alleles for stay-green was traced backward to ancestral lines and forward into breeding materials derived from stay-green germplasm. The analysis of the origin of favorable alleles for stay-green helped explain why subsets of stay-green QTL were identified in different studies and provided evidence that there may be more than one favorable allele in the sorghum germplasm for several of the stay-green QTL. Analysis of stay-green breeding lines from three public sorghum-breeding programs revealed that one of the main QTL identified in mapping studies was not being used in the breeding programs (0/13), most likely due to its association with an allele for lemon yellow seeds. In addition, a subset of the regions containing favorable alleles for staygreen from the genotype BTx642 were over represented in stay-green breeding lines. Nearly isogenic lines containing favorable alleles from BTx642 for Stg1, Stg2, Stg3, and Stg4 in a RTx7000 (senescent) background were characterized and each NIL was shown to exhibit a stay-green phenotype. Based in part on this information, fine-mapping of Stg1 was undertaken by crossing the Stg1 NIL to RTx7000. Overall, these results revealed the origin of favorable alleles for stay-green and the current utilization of alleles for stay-green in public breeding programs. In addition, this study identified additional stay-green sources that could be used for further QTL analysis and highlighted the genetic complexity of the stay-green trait.
Author: Ann E. Hagerman
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Languages : en
Pages :
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