Annual Progress Report on Malting Barley Research March, 2007

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With starch as a substrate, iodine binding is impacted by both alpha-and beta-amylases. In order to make the method specific for alpha-amylase, beta-limit dextrin is used as substrate. Beta-limit dextrin is prepared by exhaustively reacting starch with a purified beta-amylase. Beta-amylase hydrolyzes starch from the non-reducing end to yield maltose. As it can not pass alpha-1,6 linkages in the starch, a beta-limit dextrin product results in addition to the maltose (figure 2). Beta-Amylase Alpha- 1, 6 branch + Maltose starch Beta-Limit Dextrin Figure 2. Preparation of beta-limit dextrin from starch using purified beta-amylase. Arrows show points at which beta-amylase can hydrolyze alpha-1,4 linkages in starch. In theory, the beta-limit dextrin can no longer be attacked by beta-amylase, and its use as a substrate makes the method specific for alpha-amylase. Alpha-amylase is an endo-enzyme, meaning it attacks the beta-limit dextrin internally and forms small oligosaccharides (figure 3). Loss of iodine binding is thus believed only to be associated only with the alpha-amylase in the malt sample. 78
Beta-limit dextrin Alpha-Amylase Alpha- 1, 6 branch Small dextrin + sugars Figure 3. Endo-activity of alpha-amylase on beta-limit dextrin substrate. Products are small dextrins and sugars. As the size of the substrate decreases, the ability to bind iodine is lost. However, the situation is not as simple as presented in figure 3. Starch (amylopectin) is described as being composed of A, B and C-Chains. The C-chain is the central chain carrying the reducing group, while the outermost A-chains are unbranched. While the Bchains are branched, they may have very long unbranched segments. Figure 4 shows a representative diagram of a portion of the starch molecule (the complete molecule may contain > 1 x 10 6 glucose residues). The shaded circles show glucose residues that would be initially removed by beta-amylase (as maltose) in the preparation of beta-limit dextrin. However, when the beta-limit dextrin is used in the assay of alpha-amylase, its action opens up these unbranched B-chain residues, and they then become susceptible to beta-amylase. The glucose residues that would become susceptible to beta-, only after attack by alpha-amylase are shown with striped circles. The length of these susceptible unbranched B-regions can be considerable (>50 glucose) and they are associated with iodine binding. As such, it seems possible that the use of beta-limit dextrin in the assay of malt alpha-amylase may not completely eliminate interference from beta-amylase. 79
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Annual Pro
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-i- INTRODUCTION The March 2007 <st
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USDA-ARS NORTHERN CROP SCIENCE LABO
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Spring Regional over two years at D
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Table 1. 2006 UCD Two-Rowed Malting
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environments was practiced, 2) elit
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Table 4. Selected six-rowed lines c
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Other Barley Research: Feed Program
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Executive Summary AMBA Prog
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Table 1. Agronomic performance of M
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Lines M122 and M124 were rated sati
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EARLY GENERATION LINES Forty F5 pop
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have evaluated a PCR based marker,
Page 27 and 28: Edward Schiefelbein, Research Scien
Page 29 and 30: small grains pathology input to thi
Page 31 and 32: Project Personnel Small Grains Path
Page 33 and 34: Investigations on Barley Diseases a
Page 35 and 36: Minnesota barley disease survey and
Page 37 and 38: pathotypes at the seedling stage in
Page 39 and 40: germplasm with the highest level of
Page 41 and 42: Mirlohi, A., Brueggeman, R., Steffe
Page 43 and 44: Developing Improved Malt Barley Var
Page 45 and 46: Table 2. Montana’s Statewide Tria
Page 47 and 48: As a Barley CAP collaborator, our C
Page 49 and 50: 3.2. A barley nursery composed of d
Page 51 and 52: 5. Related Barley Projects Barley P
Page 53 and 54: Barley Breeding - Advanced Testing
Page 55 and 56: Table 3. Agronomic comparisons of N
Page 57 and 58: Preliminary Malting Barley Yield Tr
Page 59 and 60: dwarf genotypes with the convention
Page 61 and 62: STUDIES ON BARLEY DISEASES AND THEI
Page 63 and 64: inoculated plots. The inoculum used
Page 65 and 66: much of North Dakota in 2006, few f
Page 67 and 68: 5. Collect isolates of barley patho
Page 69 and 70: oot rot. In collaboration with Scot
Page 71 and 72: 2. United States Wheat and Barley S
Page 73 and 74: 6. Lee, S. and Neate, S.M. (2006) P
Page 75 and 76: Objectives Met in the One-Year Fund
Page 77: These automated methods have been t
Page 81 and 82: M w kDa 800 600 400 200 0 0.4 0 2 4
Page 83 and 84: Figure 7. Time course of I2-binding
Page 85 and 86: 10 9 8 7 6 5 4 3 2 1 0 1993 1994 19
Page 87 and 88: 2. Other Research (A) Predicting Se
Page 89 and 90: forms (through enzymolysis during m
Page 91 and 92: PUBLICATIONS (2006-07) Schwarz, P.B
Page 93 and 94: CI9214, PI552963 (Heartland), and N
Page 95 and 96: showing good levels of resistance t
Page 97 and 98: Germplasm Enhancement for RWA Resis
Page 99 and 100: Gary Hein in Colorado and Nebraska.
Page 101 and 102: Kevin Hicks, Research Leader, USDA-
Page 103 and 104: Detailed Report on
Page 105 and 106: Other Barley Research and Future Di
Page 107 and 108: Table 1. 2006/2007 Oregon winter ba
Page 109 and 110: Table 4. Agronomic data for OSU win
Page 111 and 112: MALTING QUALITY ANALYSIS OF NEW BAR
Page 113 and 114: We recently secured an industrial c
Page 115 and 116: 2006-2007 Progress
Page 117 and 118: enzyme it encodes. We found that se
Page 119 and 120: horseradish peroxidase-conjugated g
Page 121 and 122: found in plant cell walls. The degr
Page 123 and 124: Establishing that sequence variatio
Page 125: Charles Karpelenia, technician Joe
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Annual Progress Report on Malting Barley Research March, 2007

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