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Title: Characterization of novel sorghum brown midrib mutants from an EMS-mutagenized population

Abstract

Reducing lignin concentration in lignocellulosic biomass can increase forage digestibility for ruminant livestock and saccharification yields of biomass for bioenergy. In sorghum ( Sorghum bicolor (L.) Moench) and several other C4 grasses, brown midrib ( bmr) mutants have been shown to reduce lignin concentration. Putative bmr mutants isolated from an EMS-mutagenized population were characterized and classified based on their leaf midrib phenotype and allelism tests with the previously described sorghum bmr mutants bmr2, bmr6, and bmr12. These tests resulted in the identification of additional alleles of bmr2, bmr6,and bmr12, and, in addition, six bmr mutants were identified that were not allelic to these previously described loci. Further allelism testing among these six bmr mutants showed that they represented four novel bmr loci. Based on this study, the number of bmr loci uncovered in sorghum has doubled. The impact of these lines on agronomic traits and lignocellulosic composition was assessed in a 2-yr field study. Most of the identified bmr lines showed reduced lignin concentration of their biomass relative to wild-type (WT). Effects of the six new bmr mutants on enzymatic saccharification of lignocellulosic materials were determined, but the amount of glucose released from the stover was similar to WT inmore » all cases. Like bmr2, bmr6, and bmr12, these mutants may affect monolignol biosynthesis and may be useful for bioenergy and forage improvement when stacked together or in combination with the three previously described bmr alleles.« less

Authors:
 [1];  [2];  [3];  [1];  [2];  [1]
  1. USDA-ARS, Lincoln, NE (United States); Univ. of Nebraska-Lincoln, Lincoln, NE (United States)
  2. Univ. of Florida, Gainesville, FL (United States)
  3. USDA-ARS, Lubbock, TX (United States)
Publication Date:
Research Org.:
Univ. of Florida, Gainesville, FL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1222462
Grant/Contract Number:
FG02-07ER64458
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
G3
Additional Journal Information:
Journal Volume: 4; Journal Issue: 11; Journal ID: ISSN 2160-1836
Publisher:
Genetics Society of America
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 09 BIOMASS FUELS; acid detergent; lignin (ADL); ethyl methanesulfonate (EMS); bioenergy; forage; composition; allelism

Citation Formats

Sattler, Scott E., Saballos, Ana, Xin, Zhanguo, Funnell-Harris, Deanna L., Vermerris, Wilfred, and Pedersen, Jeffrey F.. Characterization of novel sorghum brown midrib mutants from an EMS-mutagenized population. United States: N. p., 2014. Web. doi:10.1534/g3.114.014001.
Sattler, Scott E., Saballos, Ana, Xin, Zhanguo, Funnell-Harris, Deanna L., Vermerris, Wilfred, & Pedersen, Jeffrey F.. Characterization of novel sorghum brown midrib mutants from an EMS-mutagenized population. United States. doi:10.1534/g3.114.014001.
Sattler, Scott E., Saballos, Ana, Xin, Zhanguo, Funnell-Harris, Deanna L., Vermerris, Wilfred, and Pedersen, Jeffrey F.. Tue . "Characterization of novel sorghum brown midrib mutants from an EMS-mutagenized population". United States. doi:10.1534/g3.114.014001. https://www.osti.gov/servlets/purl/1222462.
@article{osti_1222462,
title = {Characterization of novel sorghum brown midrib mutants from an EMS-mutagenized population},
author = {Sattler, Scott E. and Saballos, Ana and Xin, Zhanguo and Funnell-Harris, Deanna L. and Vermerris, Wilfred and Pedersen, Jeffrey F.},
abstractNote = {Reducing lignin concentration in lignocellulosic biomass can increase forage digestibility for ruminant livestock and saccharification yields of biomass for bioenergy. In sorghum (Sorghum bicolor (L.) Moench) and several other C4 grasses, brown midrib (bmr) mutants have been shown to reduce lignin concentration. Putative bmr mutants isolated from an EMS-mutagenized population were characterized and classified based on their leaf midrib phenotype and allelism tests with the previously described sorghum bmr mutants bmr2, bmr6, and bmr12. These tests resulted in the identification of additional alleles of bmr2, bmr6,and bmr12, and, in addition, six bmr mutants were identified that were not allelic to these previously described loci. Further allelism testing among these six bmr mutants showed that they represented four novel bmr loci. Based on this study, the number of bmr loci uncovered in sorghum has doubled. The impact of these lines on agronomic traits and lignocellulosic composition was assessed in a 2-yr field study. Most of the identified bmr lines showed reduced lignin concentration of their biomass relative to wild-type (WT). Effects of the six new bmr mutants on enzymatic saccharification of lignocellulosic materials were determined, but the amount of glucose released from the stover was similar to WT in all cases. Like bmr2, bmr6, and bmr12, these mutants may affect monolignol biosynthesis and may be useful for bioenergy and forage improvement when stacked together or in combination with the three previously described bmr alleles.},
doi = {10.1534/g3.114.014001},
journal = {G3},
number = 11,
volume = 4,
place = {United States},
year = {Tue Sep 02 00:00:00 EDT 2014},
month = {Tue Sep 02 00:00:00 EDT 2014}
}

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Cited by: 12works
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  • Cited by 10
  • For biofuel production processes to be economically efficient, it is essential to maximize the production of monomeric carbohydrates from the structural carbohydrates of feedstocks. One strategy for maximizing carbohydrate production is to identify less recalcitrant feedstock cultivars by performing some type of experimental screening on a large and diverse set of candidate materials, or by identifying genetic modifications (random or directed mutations or transgenic plants) that provide decreased recalcitrance. Economic efficiency can also be increased using additional pretreatment processes such as deacetylation, which uses dilute NaOH to remove the acetyl groups of hemicellulose prior to dilute acid pretreatment. In thismore » work, we used a laboratory-scale screening tool that mimics relevant thermochemical pretreatment conditions to compare the total sugar yield of three near-isogenic brown midrib (bmr) mutant lines and the wild-type (WT) sorghum cultivar. We then compared results obtained from the laboratory-scale screening pretreatment assay to a large-scale pretreatment system. After pretreatment and enzymatic hydrolysis, the bmr mutants had higher total sugar yields than the WT sorghum cultivar. Increased pretreatment temperatures increased reactivity for all sorghum samples reducing the differences observed at lower reaction temperatures. Deacetylation prior to dilute acid pretreatment increased the total sugar yield for all four sorghum samples, and reduced the differences in total sugar yields among them, but solubilized a sizable fraction of the non-structural carbohydrates. The general trends of increased total sugar yield in the bmr mutant compared to the WT seen at the laboratory scale were observed at the large-scale system. However, in the larger reactor system, the measured total sugar yields were lower and the difference in total sugar yield between the WT and bmr sorghum was larger. Sorghum bmr mutants, which have a reduced lignin content showed higher total sugar yields than the WT cultivar after dilute acid pretreatment and enzymatic hydrolysis. In conclusion, deacetylation prior to dilute acid pretreatment increased the total sugar yield for all four sorghum samples. However, since deacetylation also solubilizes a large fraction of the non-structural carbohydrates, the ability to derive value from these solubilized sugars will depend greatly on the proposed conversion process.« less
  • Colletotrichum sublineola is an aggressive fungal pathogen that causes anthracnose in sorghum [ Sorghum bicolor (L.) Moench]. The obvious symptoms of anthracnose are leaf blight and stem rot. Sorghum, the fifth most widely grown cereal crop in the world, can be highly susceptible to the disease, most notably in hot and humid environments. In the southeastern United States the acreage of sorghum has been increasing steadily in recent years, spurred by growing interest in producing biofuels, bio-based products, and animal feed. Resistance to anthracnose is, therefore, of paramount importance for successful sorghum production in this region. To identify anthracnose resistancemore » loci present in the highly resistant cultivar ‘Bk7’, a biparental mapping population of F 3:4 and F 4:5 sorghum lines was generated by crossing ‘Bk7’ with the susceptible inbred ‘Early Hegari-Sart’. Lines were phenotyped in three environments and in two different years following natural infection. The population was genotyped by sequencing. Following a stringent custom filtering protocol, totals of 5186 and 2759 informative SNP markers were identified in the two populations. Segregation data and association analysis identified resistance loci on chromosomes 7 and 9, with the resistance alleles derived from ‘Bk7’. Both loci contain multiple classes of defense-related genes based on sequence similarity and gene ontologies. In addition, genetic analysis following an independent selection experiment of lines derived from a cross between ‘Bk7’ and sweet sorghum ‘Mer81-4’ narrowed the resistance locus on chromosome 9 substantially, validating this QTL. As observed in other species, sorghum appears to have regions of clustered resistance genes. Further characterization of these regions will facilitate the development of novel germplasm with resistance to anthracnose and other diseases.« less
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