Publications by authors named "Mergoum M"

43 Publications

Effect of Pre-Harvest Sprouting on Physicochemical Properties of Starch in Wheat.

Foods 2014 Apr 8;3(2):194-207. Epub 2014 Apr 8.

Department of Plant Sciences, North Dakota State University, P.O. Box 6050, Department #7670, Fargo, ND 58108-6050, USA.

Pre-harvest sprouting (PHS) in wheat ( L.) occurs when physiologically mature kernels begin germinating in the spike. The objective of this study was to provide fundamental information on physicochemical changes of starch due to PHS in Hard Red Spring (HRS) and Hard White Spring (HWS) wheat. The mean values of α-amylase activity of non-sprouted and sprouted wheat samples were 0.12 CU/g and 2.00 CU/g, respectively. Sprouted samples exhibited very low peak and final viscosities compared to non-sprouted wheat samples. Scanning electron microscopy (SEM) images showed that starch granules in sprouted samples were partially hydrolyzed. Based on High Performance Size Exclusion Chromatography (HPSEC) profiles, the starch from sprouted samples had relatively lower molecular weight than that of non-sprouted samples. Overall, high α-amylase activity caused changes to the physicochemical properties of the PHS damaged wheat.
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http://dx.doi.org/10.3390/foods3020194DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5302366PMC
April 2014

Effect of pre-harvest sprouting on physicochemical changes of proteins in wheat.

J Sci Food Agric 2014 Jan 27;94(2):205-12. Epub 2013 Jun 27.

Department of Plant Sciences, North Dakota State University, Fargo, ND, 58108-6050, USA.

Background: High moisture before harvest can cause sprouting of the wheat kernel, which is termed pre-harvest sprouting (PHS). The aim of this study was to examine the variation in physicochemical properties of proteins in PHS-damaged (sprouted) hard red and white spring wheat genotypes. Specifically, protein content, enzyme activity and degradation of proteins were evaluated in sound and PHS-damaged wheat.

Results: Protein contents of sprouted wheat samples were lower than that of non-sprouted samples; however, their differences were not significantly (P > 0.05) correlated with sprouting score. Sodium dodecyl sulfate (SDS) buffer extractable proteins (EXP) and unextractable proteins (UNP) were analyzed by high-performance size exclusion chromatography. PHS damage elevated endoprotease activity and consequently increased the degradation of polymeric UNP and free asparagine concentration in wheat samples. Free asparagine is known to be a precursor for formation of carcinogenic acrylamide during high heat treatment, such as baking bread. Free asparagine content had significant correlations (P < 0.01) with sprouting score, endoprotease activity and protein degradation.

Conclusions: Genotypes with higher endoprotease activity tend to exhibit a larger degree of degradation of UNP and higher free asparagine concentration in sprouted wheat samples.
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http://dx.doi.org/10.1002/jsfa.6229DOI Listing
January 2014

Interdependence of Cultivar and Environment on Fiber Composition in Wheat Bran.

Aust J Crop Sci 2013 ;7(4):525-531

Dept. of Plant Sciences, North Dakota State University, Fargo, ND, USA.

Starch and cellulose are among the best known renewable reinforcing components. Scientists are continuously looking for various renewable sources such as flax, hemp, jute, and corn hulls with polymer matrixes to form composite materials and make structural biocomposites a reality. Wheat is a major cereal grain in the US and the world. During wheat milling, a large amount of wheat bran, a by-product, is disposed off as waste. The high percentage of water-insoluble fiber in wheat bran could be advantageous for reinforcing industrial material. However, the utilization of cellulosic fibers derived from wheat byproduct has not been explored in processing of biocomposites. Therefore, the objectives of this study were to characterize wheat bran fiber compositions including dry matter (DM), ash, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose (Cell), hemicellulose (Hemi), calcium (Ca), fat, starch, and acid detergent lignin (ADL); identify the interrelationship between the fiber composition traits and the influence of the environment and genotype on these traits. The experiment included six diverse and popular hard red spring wheat (HRSW) cultivars commonly grown in spring wheat region of the Northern Plains of USA. The experiment was installed in three different environments in the Dakotas States, USA. Results from this study showed that the DM, ash, Ca, Cell, starch, and ADL contents were influenced mainly by environments. However, CP along with fat, ash and Ca contents were influenced by genotypes in addition to environment. All bran components were influenced by the genotype × environment (G × E) interactions. We observed significant negative correlation of Cell with CP and ADL which make wheat bran a suitable reinforcing industrial material. However surface treatment of bran fiber would make it even more efficient. These preliminary results indicate the potential use of wheat bran components as biocomposite, but further studies to elucidate more these finding are warranted.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6105293PMC
January 2013

Mixed model association mapping for fusarium head blight resistance in tunisian-derived durum wheat populations.

G3 (Bethesda) 2011 Aug 1;1(3):209-18. Epub 2011 Aug 1.

Sources of resistance to Fusarium head blight (FHB) in wheat are mostly restricted to Chinese hexaploid genotypes. The effort to incorporate the resistance from hexaploid wheat or wild relatives to cultivated durum wheat (Triticum turgidum L. var. durum Desf.) have not been successful in providing resistance to the level of the donor parents. In this study, we used 171 BC(1)F(6) and 169 BC(1)F(7) lines derived from crossing of four Tunisian tetraploid sources of resistance (Tun7, Tun18, Tun34, Tun36) with durum cultivars 'Ben,' 'Maier,' 'Lebsock,' and 'Mountrail' for association studies. The Tun18 and Tun7 FHB resistances were found to be comparable to the best hexaploid wheat sources. A new significant QTL for FHB resistance was identified on the long arm of chromosome 5B (Qfhs.ndsu-5BL) with both association and classical QTL mapping analysis. Linkage disequilibrium (LD) blocks extending up to 40 cM were evident in these populations. The linear mixed model considering the structure (Q or P) and the kinship matrix (K(T)) estimated by restricted maximum likelihood (REML) was identified as the best for association studies in a mixture of wheat populations from a breeding program. The results of association mapping analysis also demonstrated a region on the short arm of chromosome 3B as potentially linked to FHB resistance. This region is in proximity of major FHB resistance gene fhb1 reported in hexaploid wheat. A possibility of having susceptibility or suppressor of resistance gene(s) on durum wheat chromosome 2A was further confirmed in this material, explaining the problem in developing resistant genotypes without counter selection against this region.
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http://dx.doi.org/10.1534/g3.111.000489DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3276138PMC
August 2011

Identification of novel genomic regions associated with resistance to Pyrenophora tritici-repentis races 1 and 5 in spring wheat landraces using association analysis.

Theor Appl Genet 2011 Oct 9;123(6):1029-41. Epub 2011 Jul 9.

Department of Plant Pathology, North Dakota State University, NDSU Dept. 7660, P.O. Box 6050, Fargo, ND 58108-6050, USA.

Tan spot, caused by Pyrenophora tritici-repentis, is a major foliar disease of wheat worldwide. Host plant resistance is the best strategy to manage this disease. Traditionally, bi-parental mapping populations have been used to identify and map quantitative trait loci (QTL) affecting tan spot resistance in wheat. The association mapping (AM) could be an alternative approach to identify QTL based on linkage disequilibrium (LD) within a diverse germplasm set. In this study, we assessed resistance to P. tritici-repentis races 1 and 5 in 567 spring wheat landraces from the USDA-ARS National Small Grains Collection (NSGC). Using 832 diversity array technology (DArT) markers, QTL for resistance to P. tritici-repentis races 1 and 5 were identified. A linear model with principal components suggests that at least seven and three DArT markers were significantly associated with resistance to P. tritici-repentis races 1 and 5, respectively. The DArT markers associated with resistance to race 1 were detected on chromosomes 1D, 2A, 2B, 2D, 4A, 5B, and 7D and explained 1.3-3.1% of the phenotypic variance, while markers associated with resistance to race 5 were distributed on 2D, 6A and 7D, and explained 2.2-5.9% of the phenotypic variance. Some of the genomic regions identified in this study correspond to previously identified loci responsible for resistance to P. tritici-repentis, offering validation for our AM approach. Other regions identified were novel and could possess genes useful for resistance breeding. Some DArT markers associated with resistance to race 1 also were localized in the same regions of wheat chromosomes where QTL for resistance to yellow rust, leaf rust and powdery mildew, have been mapped previously. This study demonstrates that AM can be a useful approach to identify and map novel genomic regions involved in resistance to P. tritici-repentis.
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http://dx.doi.org/10.1007/s00122-011-1645-1DOI Listing
October 2011

Refrigerated dough quality: effect of environment and genotypes of hard red spring wheat.

J Food Sci 2011 Jan-Feb;76(1):S101-7. Epub 2010 Nov 10.

North Dakota State Univ., Dept. of Plant Sciences, PO Box 6050, Dept# 7670 Fargo, ND 58108-6050, USA.

Refrigerated dough products use wheat flour as their primary ingredient, so the quality and chemical composition of the flour determine the quality of the final product. Six varieties of hard red spring wheat, grown in 3 locations in Minnesota, U.S.A., were evaluated for use in refrigerated dough products. Total arabinoxylan percentages in the flours ranged from 0.97 to 1.54. Xylanase activity of the flour was measured and ranged from 0.20 to 0.84 mU/g. An important factor in the suitability for refrigerated dough is the syruping during storage. A large amount of variability in dough syruping was observed among the varieties and locations when the extent of dough syruping was measured over a period of 10 d. The mean dough syruping on day 10 ranged from 2.05% to 14.83%. Despite the significant interaction effect of genotype and environment, 2 varieties, Glenn and Oklee, had lower dough syrup formation with greater stability across growing locations and storage days than other varieties. Practical Application: Refrigerated dough production is one of the fastest growing segments of the ready-to-use food industry. Well-formulated and processed refrigerated doughs are practical to consume and should stay fresh during extended periods of storage; thus, maintenance of dough quality during refrigeration is critical. This study was designed to perform the research on genotypic and environmental effects on variations in dough syruping during refrigeration storage of doughs from hard red spring wheats.
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http://dx.doi.org/10.1111/j.1750-3841.2010.01895.xDOI Listing
September 2011

Genetic analysis of resistance to Pyrenophora tritici-repentis races 1 and 5 in tetraploid and hexaploid wheat.

Phytopathology 2008 Jun;98(6):702-8

Department of Plant Science, North Dakota State University, Fargo 58105, USA.

Tan spot of wheat, caused by the fungus Pyrenophora tritici-repentis, is a destructive disease worldwide that can lead to serious losses in quality and quantity of wheat grain production. Resistance to multiple races of P. tritici-repentis was identified in a wide range of genetically diverse genotypes, including three different species Triticum aestivum (AABBDD), T. spelta (AABBDD), and T. turgidum (AABB). The major objectives of this study were to determine the genetic control of resistance to P. tritici-repentis races 1 and 5 in 12 newly identified sources of resistance. The parents, F(1), F(2), and F(2:3) or F(2:5) families of each cross were analyzed for the allelism tests and/or inheritance studies. Plants were inoculated at the two-leaf stage under controlled environmental conditions and disease reaction was assessed based on lesion-type rating scale. A single recessive gene controlled resistance to necrosis caused by P. tritici-repentis race 1 in both tetraploid and hexaploid resistant genotypes. The lack of segregation in the inter- and intra-specific crosses between the resistant tetraploid and hexaploid genotypes indicated that they possess the same genes for resistance to tan necrosis and chlorosis induced by P. tritici-repentis race 1. A single dominant gene for chlorosis in hexaploid wheat and a single recessive gene for necrosis in tetraploid wheat, controlled resistance to P. tritici-repentis race 5.
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http://dx.doi.org/10.1094/PHYTO-98-6-0702DOI Listing
June 2008

Identification and Molecular Mapping of a Gene Conferring Resistance to Pyrenophora tritici-repentis Race 3 in Tetraploid Wheat.

Phytopathology 2006 Aug;96(8):885-9

ABSTRACT Race 3 of the fungus Pyrenophora tritici-repentis, causal agent of tan spot, induces differential symptoms in tetraploid and hexaploid wheat, causing necrosis and chlorosis, respectively. This study was conducted to examine the genetic control of resistance to necrosis induced by P. tritici-repentis race 3 and to map resistance genes identified in tetraploid wheat (Triticum turgidum). A mapping population of recombinant inbred lines (RILs) was developed from a cross between the resistant genotype T. tur-gidum no. 283 (PI 352519) and the susceptible durum cv. Coulter. Based on the reactions of the Langdon-T. dicoccoides (LDN[DIC]) disomic substitution lines, chromosomal location of the resistance genes was determined and further molecular mapping of the resistance genes for race 3 was conducted in 80 RILs of the cross T. turgidum no. 283/Coulter. Plants were inoculated at the two-leaf stage and disease reaction was assessed 8 days after inoculation based on lesion type. Disease reaction of the LDN(DIC) lines and molecular mapping on the T. turgidum no. 283/Coulter population indicated that the gene, designated tsn2, conditioning resistance to race 3 is located on the long arm of chromosome 3B. Genetic analysis of the F(2) generation and of the F(4:5) and F(6:7) families indicated that a single recessive gene controlled resistance to necrosis induced by race 3 in the cross studied.
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http://dx.doi.org/10.1094/PHYTO-96-0885DOI Listing
August 2006

Genetic structure of Phaeosphaeria nodorum populations in the north-central and midwestern United States.

Phytopathology 2008 Jan;98(1):101-7

Department of Plant Pathology, North Dakota State University, Fargo, ND 58105, USA.

Stagonospora nodorum blotch, caused by Phaeosphaeria nodorum, is considered one of the most destructive foliar diseases of wheat in the United States. However, relatively little is known about the population biology of this fungus in the major wheat-growing regions of the central United States. To rectify this situation, 308 single-spore isolates of P. nodorum were analyzed from 12 populations, five from hard red spring wheat cultivars in Minnesota and North Dakota and seven from soft red winter wheat in Indiana and Ohio. The genetic structure of the sampled populations was determined by analyzing polymorphisms at five microsatellite or simple-sequence repeat (SSR) loci and the mating type locus. Although a few clones were identified, most P. nodorum populations had high levels of gene (H(S) = 0.175 to 0.519) and genotype (D = 0.600 to 0.972) diversity. Gene diversity was higher among isolates collected from spring wheat cultivars in North Dakota and Minnesota (mean H(S) = 0.503) than in those from winter wheat cultivars in Indiana and Ohio (H(S) = 0.269). Analyses of clone-corrected data sets showed equal frequencies of both mating types in both regional and local populations, indicating that sexual recombination may occur regularly. However, significant gametic disequilibrium occurred in three of the four populations from North Dakota, and there was genetic differentiation both within and among locations. Genetic differentiation between the hard red spring and soft red winter wheat production regions was moderate (F(ST) = 0.168), but whether this is due to differences in wheat production or to geographical variation cannot be determined. These results suggest that sexual reproduction occurs in P. nodorum populations in the major wheat-growing regions of the central United States, and that geographically separated populations can be genetically differentiated, reflecting either restrictions on gene flow or selection.
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http://dx.doi.org/10.1094/PHYTO-98-1-0101DOI Listing
January 2008

Reaction of Elite Wheat Genotypes from the Northern Great Plains of North America to Septoria Diseases.

Plant Dis 2007 Oct;91(10):1310-1315

Department of Plant Pathology, North Dakota State University.

Stagonospora nodorum blotch (SNB), caused by Phaeosphaeria nodorum, and Septoria tritici blotch (STB), caused by Mycosphaerella graminicola, are the main pathogens of the Septoria disease complex of wheat (Triticum aestivum) in North America. This study was conducted to determine the disease reaction of 126 elite hard red spring, white, and durum wheat cultivars and advanced breeding lines collected from the northern Great Plains of the United States and Canada to SNB and STB. Seedlings of the 126 wheat genotypes were evaluated for resistance to SNB and STB under controlled environmental conditions. Moreover, these 126 wheat genotypes also were infiltrated with culture filtrate of P. nodorum isolate Sn2000. Based on disease reactions, three cultivars (McNeal, Dapps, and Oklee) and 12 advanced breeding lines (CA-901-580W, 97SO254-8-1, MN03291, MN03308, WA007925, MT0245, ND756, ND801, ND803, ND808, ND809, and ND811) adapted to the northern Great Plains were found to be resistant to both Septoria diseases and insensitive to the culture filtrate. Additionally, eight genetically diverse lines and cultivars, including two tetraploid wheat genotypes, were identified to be resistant to both Septoria diseases. These results suggest that the wheat genotypes contain a broad genetic base for resistance to the Septoria diseases in the northern Great Plains of the United States and Canada, and the resistant sources identified in this study may be utilized in wheat-breeding programs.
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http://dx.doi.org/10.1094/PDIS-91-10-1310DOI Listing
October 2007

Molecular mapping of kernel shattering and its association with Fusarium head blight resistance in a Sumai3 derived population.

Theor Appl Genet 2007 Oct 24;115(6):757-66. Epub 2007 Jul 24.

Department of Plant Sciences, North Dakota State University, Fargo, ND 58105, USA.

Kernel shattering (KS) can cause severe grain yield loss in wheat (Triticum aestivum L.). The introduction of genotypes with Fusarium head blight (FHB) resistance has elevated the KS importance. 'Sumai3,' the most commonly used FHB-resistant germplasm worldwide, is reported to be KS susceptible. The objectives of this study were to detect quantitative trait loci (QTLs) for KS and to determine the relationship between KS and FHB. A recombinant inbred line population derived from a cross between Sumai3 and 'Stoa' was evaluated for KS in five environments and FHB in two field trials, separately. Four genomic regions on chromosomes 2B, 3B, and 7A were associated with KS. Of them, two major KS QTLs were detected consistently over three environments and each located proximal to the centromere on chromosomes 3B and 7A. The resistant alleles at these two QTLs together can reduce KS by 66.1% relative to the reciprocal alleles and by 41.1% compared to the population mean. The field FHB data revealed four QTLs on chromosomes 2B, 3B, and 7A. Three of these FHB QTLs coincided with and/or linked to the KS QTLs with opposite allele effects in the corresponding genomic regions, which may explain the negative correlation (r = -0.29 and P < 0.01) between the KS and FHB infection found in this study. The results in this study indicate that KS and FHB in Sumai3 are, in part, inherited dependently. However, the correlation between KS and FHB is not strong, and the major FHB resistance QTL on chromosome arm 3BS was not linked to any KS QTL. Our results showed that pyramiding of the two major KS-resistant alleles and the unlinked major FHB-resistant allele could produce lines with both low values of KS and FHB infection.
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http://dx.doi.org/10.1007/s00122-007-0606-1DOI Listing
October 2007

Evaluation of Elite Wheat Germ Plasm for Resistance to Tan Spot.

Plant Dis 2006 Oct;90(10):1320-1325

Department of Plant Sciences, 166-Loftsgard Hall, North Dakota State University, Fargo 58105.

Tan spot, caused by Pyrenophora tritici-repentis, is a serious foliar disease of wheat (Triticum aestivum) in North America. Control of tan spot through management practices and fungicide application is possible; however, the use of resistant varieties is the most effective and economical means of controlling tan spot. This study was conducted to determine the disease reaction of 126 elite hard red spring, white, and durum wheat varieties and advanced breeding lines collected from the northern Great Plains of the United States and Canada to individual races/toxins of P. tritici-repentis. Seedling evaluation of the 126 genotypes was done under controlled environmental conditions with virulent races 2, 3, and 5 of P. tritici-repentis and toxins Ptr ToxA and Ptr ToxB. Based on disease reactions, two resistant varieties and two advanced breeding lines adapted to the northern Great Plains were found to be resistant to all the races and insensitive to the toxins tested. Additionally, six genetically diverse lines/varieties were identified to be resistant to tan spot; however, these sources may not be well adapted to the northern Great Plains. These results suggest that the wheat germ plasm contains a broad genetic base for resistance to the most prevalent races of P. tritici-repentis in North America, and the resistant sources identified in this study may be utilized in wheat breeding programs to develop tan spot resistant varieties.
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http://dx.doi.org/10.1094/PD-90-1320DOI Listing
October 2006

Evaluation of Resistance of Winter Wheat to Fusarium acuminatum by Inoculation of Seedling Roots with Single, Germinated Macroconidia.

Plant Dis 1998 Mar;82(3):300-302

Professor, Department of Soil and Crop Sciences, Colorado State University, Fort Collins 80523.

Fusarium acuminatum is one of the causal agents of dryland root rot of winter wheat in Colorado. The effect of F. acuminatum seedling root infection, recorded at heading, on winter wheat cultivars Sandy and CO84 was investigated in the greenhouse. Winter wheat seeds were surface disinfested, germinated, and vernalized. Vernalized seedling roots were inoculated by placing a single, germinated macroconidium of F. acuminatum on the largest root. Inoculated and non-inoculated vernalized seedlings were transplanted to pots and half the plants subjected to water stress. Inoculated plants had significantly lower survival rates and, at maturity, lower relative leaf water content, fewer tillers, shorter plant height, and higher cell ion leakage than non-inoculated plants. Wheat cultivars differed significantly for most traits studied. CO84 was susceptible whereas Sandy was more tolerant of the pathogen, particularly under water stress conditions. These results suggest that relative leaf water content, cell ion leakage, and to some extent seedling survival may be useful attributes for evaluation of resistance to the root rot pathogen.
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http://dx.doi.org/10.1094/PDIS.1998.82.3.300DOI Listing
March 1998
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