Winter triticale breeding.

P.S. Baenziger.

Triticale breeding continues with an increased emphasis on forage production and winterhardiness. Currently, our triticales have a level of winterhardiness that is superior to that of our winter barley program, but only equal to the moderately winter-hardy winter wheats. No triticale has the winterhardiness of our best winter wheats (i.e., Arapahoe or Redland). Though most winter triticale germplasm tend to be late, our breeding efforts have concentrated on developing triticales that are earlier than winter wheat, but not as early as winter barley. The goals are to have both winter triticale and barley harvested before the main wheat harvest begins and to cut the forage early in the season to provide greater flexibility in cropping rotations that require extended fallow periods or have short-season crops. The superior disease resistance of triticale compared to wheat was apparent in eastern Nebraska, where triticale had grain yields of 150 % of those of winter wheats. In a more normal year, they would have comparable yields.

Role of RNA-degrading enzymes in regulating gene expression.

Y. Yen and P.S. Baenziger.

Research on wheat RNA-degrading enzymes is ongoing. Seventeen RNA-degrading enzyme activities of common wheat, with apparent molecular masses from 42.2 kD to 16.3 kD, were observed by the RNA-SDS-PAGE assay. To determine their chromosome locations, all chromosome arms of common wheat, except chromosome arm 4BS, were assayed in their null condition, using a set of ditelosomic or nulli-tetrasomic lines of the cultivar Chinese Spring. Our results showed that the loci for the 22.8 kD and the 21.2 kD enzymes are located on chromosome arm 2AS, and the locus for the 21.6 kD enzymes on chromosome arm 2DS. Loci controlling the 20.1 kD activity were on chromosome arms 2AL, 4BS, 4DS, and 6BS. The locus or loci coding for the gene(s) of the 42.2 kD, 40.9 kD and 39.2 kD were probably located on chromosome arm 5AS, and their expression in particular and most other RNA-degrading enzyme activities in general were stimulated when chromosome arm 5AL was missing, indicating an inhibiting locus on 5AL. Our data suggested that the 31.9 kD, 30.6 kD, and 29.6 kD enzymes possibly were products of a common precursor, which might be coded by gene(s) on chromosome arm 6BS, and that the processing is co-regulated by loci on chromosome arms 2BS, 3DS, 6AL, 6BL, and 7BS. The rest of the enzyme activities were consistently found in all the lines tested and, thus, probably are encoded by multiple loci. Alternatively, their loci may be on chromosome arm 4BS, which we have not assayed in its null condition.

Variability in wheat streak mosaic virus populations.

J. Petrisko, R.C. French, G. Hein, and P.S. Baenziger.

A study of the population genetics of wheat streak mosaic virus was completed. Six counties in Nebraska were examined by collecting 20 plants/field from five fields/county in both 1994 and 1995. Viral coat protein gene and 3'-untranslated cDNA sequences were amplified by PCR and then grouped according to AluI restriction patterns. WSMV isolates were extremely variable; a total of 32 distinct banding patterns were obtained. The majority of virus isolates (81 %) belonged to one of three predominant types. Chi square analysis of the banding type frequencies indicated that as much heterogeneity occurred among virus isolates from within fields as among fields or even counties. A significant difference in banding type frequencies occurred between the two years, largely because of an increase in incidence of one particular banding type from 38 % in 1994 to 56 % in 1995.

Relationships among WSMV, AgMV, and HoMV Rymoviruses.

R.C. French.

Mite-transmitted potyviruses, of which WSMV is the type member, have been placed in the Rymovirus genus. Besides WSMV, two other viruses of wheat belonging to this genus have been found in the Great Plains. These viruses are the Agropyron mosaic rymovirus (AgMV) and Hordeum mosaic rymovirus (HoMV). In order to gain a better understanding of the relationships among viruses in this genus, and to assess the potential for them to produce new virus strains via recombination, cDNAs encompassing a portion of the polymerase and coat protein cistrons of AgMV, HoMV, and ryegrass mosaic rymovirus (RgMV) were cloned and sequenced. These three viruses were found to be quite distinct from WSMV and actually more closely related to the aphid-transmitted potyviruses. The ability to be transmitted by eriophyid mites probably evolved independently in at least two distinct potyvirus lineages. Thus, the phylogenetic status of Rymovirus is not clear, and as presently constituted, has at least two subgroupings with WSMV and brome streak mosaic rymoviruses in one group and AgMV, HoMV, and RgMV in another. Recombination between subgroups is unlikely.

Occurrence and expression of granule-bound-starch-synthase mutants in hard red winter wheat.

Bob Graybosch, Vern Hansen, and Jim Peterson.

Granule-bound-starch-synthase (GBSS) is the primary enzyme responsible for the synthesis of amylose in the starch grains of cereal endosperm cells. In maize, barley, and other cereals, mutations that eliminate the production of GBSS result in the formation of amylose-free or `waxy' starch. Bread wheats, because of their hexaploid genetic system, carry three genes encoding GBSS. These genes (Wx-A1, Wx-B1, and Wx-D1) are located on chromosomes 7A, 4A, and 7D, respectively. A spontaneous waxy mutant, therefore, could arise only by chance simultaneous mutations at all three loci, an extremely unlikely event. However, recent developments allow the separation and identification of the gene products of these three loci. Purification and separation of GBSS from more than 200 North American hexaploid wheats have led to the identification of genotypes that carry null alleles at the Wx-A1 and Wx-B1 loci. Such genotypes occurred at a frequency of less than 5 %, but were present in a number of adapted cultivars and advanced breeding lines. Wheats with single null alleles at either the Wx-A1 or Wx-B1 locus were grown, along with nonmutant `wild-type' genotypes, at two different locations in Nebraska in two harvest years. Amylose content, as measured by the blue polyiodide complex, was reduced in lines with null alleles by up to 5 % amylose. Significant environmentally induced variation in amylose content also was detected.

Genetic stocks carrying null alleles at the Glu-D1 locus.

Bob Graybosch, Jim Peterson, and Paul Mattern.

Five genetic stocks of wheat lacking Glu-D1-encoded, high-molecular-weight (HMW), glutenin, protein subunits were developed and released jointly by the USDA-ARS and the University of Nebraska, Lincoln, NE. HMW-glutenin alleles, especially those arising from the Glu-D1 locus, contribute significantly to genetic variation in wheat processing quality. N86L090 (PI591816), an F3-derived F4 selection, was descended from the cross `Brule/3/Atlas 66/NapHal//Lancota-sib/Aurora'. In addition to the Glu-D1 null-allele, N86L090 carries a 1BL.1RS wheat-rye chromosomal translocation derived from Aurora. N94L7843 (PI591817), N94L7844 (PI591818), N94L7845 (PI591819), and N94L7846 (PI591820) are four sister lines derived from `GKF8261//NapHal/CI13449/3/NE78868'. All were F3-derived F4 lines, purified by head selections made in the F6 generation.

Tannin content and wheat grain color.

Bob Graybosch, Vern Hansen, and Jim Peterson.

A biochemical assay for tannin content of wheat grain was developed and used to investigate tannin content in hard red and hard white wheats. Tannins were found to occur in white wheat, albeit at a much lower concentration than that found in red wheats. On average, red grain displayed twice as much extractable and measurable tannins than white wheats. Genetic variation in tannin content also was much higher among red wheats than among white wheats. The tannin assay would serve as a means to assist in the classification of hard red and hard white wheats, although it is too cumbersome for routine use. Tannin content was not correlated with grain polyphenol oxidase (PPO) activity; red wheats did have higher average PPO activity, but many white wheats were isolated with PPO activities that fell within the range of red wheats. Hence, whereas PPO might be involved in tannin biosynthesis, its presence does not always result in high tannin levels.

Yield stability of hybrid vs pureline hard winter wheats.

C.J. Peterson; J.M. Moffatt, Agripro Seeds, Inc.; and J.R. Erickson, formerly with HybriTech Seed, Inc.

Hybrid hard winter wheats have shown superior grain yield potential in regional performance trials. Evidence for enhanced yield stability, combined with enhanced yield potential, would facilitate wider acceptance of hybrid wheat by growers. Hybrid and pureline yield stability and response were compared in the Southern Regional Performance Nursery (SRPN), 1990 through 1995, and the Agripro, Inc., Standard Variety Trial (SVT), 1993 and 1994. Hybrid wheats examined were developed by HybriTech Seed, Inc. or Agripro Seeds, Inc.; purelines included advanced experimental lines and current varieties from throughout the region. Hybrid and pureline yields were regressed on an environmental index based on location mean yields for purelines. Hybrids showed significantly higher mean yields compared with purelines, and the yield advantage generally increased with increasing environmental yield potential. The average regression slope was significantly higher for hybrids (1.09 to 1.12) than for purelines (1.0) in four of the eight performance trials. Hybrid slopes were not significantly different in the 1990 through 1993 SRPN. No crossover in yield response occurred between hybrids and pureline at lower yield levels. Deviations from regression response were of similar magnitude for hybrids and purelines. Hybrid wheats show potential for enhanced mean yield with greater yield response to favorable environments relative to conventional pureline cultivars.

Nebraska Wheat Quality Lab.

D.R. Shelton and W.J. Park.

The Nebraska Wheat Quality Lab has a home page on the World Wide Web: http://ianrwww.unl.edu/ianr/agronomy/wheatlab/index.htm. The goals and functions of the Lab are presented as well as information on the Nebraska Wheat Board, the Nebraska Wheat Growers Association, and U.S. Wheat Associates. Queries about wheat quality have been received from throughout the world.

Asian rolled noodle quality evaluation.

D.R. Shelton and W.J. Park.

Three sets of wheat samples were investigated for quality factors related to Asian raw rolled noodle production. The sets included 40 advanced, experimental, hard white wheat lines from two different Kansas locations (Sample Set 1); eight hard white wheat samples grown in California, Colorado, and Idaho (Sample Set 2); and 10 hard red wheat varieties grown at three Nebraska locations (Sample Set 3). Effects of variety and growing location were highly significant for wheat physical tests and milling properties in both Sample Sets 1 and 3. Relatively high test and 100-kernel weights and good milling potential were found in all sample sets. Variety had a significant influence on flour Chromameter values L (whiteness), a (greenness), or b (yellowness) for Sample Sets 1 and 3. The influence of growing location on flour Chromameter L, a, and b values was significant for Sample Set 1 but not for Sample Set 3. The trend of more variation in flour a and b values rather than L values was noted in all sample sets. The influence of variety and growing location on Mixograph results, including mixing tolerance score and peak time, were shown to contribute significantly to their variabilities in Sample Set 3.

Flour samples were processed into raw noodles using a procedure developed at the Nebraska Wheat Quality Lab. Noodle color was determined with the Chromameter after production at times 0, 6, and 12 hours. L (brightness), a (greenness), or b (yellowness) values at storage times of 0, 6, and 24 hours were influenced by either variety or growing location. Changes in brightness or green or yellow color from 0 to 6 hours or to 24 hours were different among varieties and growing locations. Noodle storage times of 0, 6, and 24 hours had a significant effect on Chromameter noodle color L, a, and b values. As storage time increased, noodle color decreased in brightness and increased in yellowness. Cooking quality characteristics (cooking time, cooking loss, cooked weight, and cooked volume) were evaluated. Variety or growing location did not significantly influence cooking quality parameters for Sample Set 3, partially because of small variations among varieties or growing locations. Noodles made from Sample Set 2 had higher weight and volume gains with less cooking loss and shorter cooking times than those from Sample Set 3.

A quantitative method also was used to determine the PPO level of wheat and flour in all three sample sets. Flour PPO activity had a significant influence on noodle color, resulting in a decrease in brightness and an increase in yellow color for Sample Set 3. Quality characteristics such as test weight, 100-kernel weight, total flour yield, and first reduction flour yield appeared to influence noodle color as well as color changes during storage. Noodle color during storage was affected significantly not only by protein contents of wheat and flour but also by color and ash contents of wheat and flour. Sheeted noodle color appears to be a complex trait. Influences of biochemical and physical quality characteristics of wheat and flour on noodle color varied among sample sets.

Personnel.

Dr. P.S. Baenziger served for the past two and one-half years as Interim Head, Department of Agronomy. He returned to his small grains breeding position with mixed emotions (joy and happiness) on 6 January, 1996. Dr. Benjamin Moreno, who served as project leader while Dr. Baenziger was interim head, accepted a wheat breeding position at North Dakota State University. Masrizal completed his Ph.D. and returned to Indonesia where he will work on rice breeding. Ms. Jill Petrisko completed her M.S. and accepted a position at the National Small Grains Collection in Aberdeen, Idaho. Mr. Mustafa Erayman, Ahmet Kumlay, and Mehmet Atak joined the program as graduate students. Dr. Jan Rybczynski joined the program as a visiting scientist supported by a Fulbright Fellowship to study triticale and rye tissue culture and transformation.

Publications.

Baenziger PS, Crosby WL, Merrigan KA, and Womack JE. 1995. Research policy. In: NABC Report 7: Genes for the Future: Discovery, Ownership, Access. (MacDonald JF ed). National Agricultural Biotechnology Council, Ithaca, NY. Pp. 29-36.

Baenziger PS, Moreno-Sevilla B, Peterson CJ, Schmidt JW, Shelton DR, Baltensperger DD, Nelson LA, McVey DV, Watkins JE, and Hatchett JH. 1995. Registration of `Alliance' wheat. Crop Sci 35:938.

Budak N, Baenziger PS, and Eskridge KM. 1995. Effect of replications on measuring wheat plant height. Can J Plant Sci 75:171-173.

Budak N, Baenziger PS, Eskridge KM, Baltensperger DD, and Moreno-Sevilla B. 1995. Plant height response of semidwarf and nonsemidwarf wheats to the environment. Crop Sci 35:447-451.

French R. 1995. Barley yellow dwarf: diagnostic procedures and reagents In: `Barley Yellow Dwarf: 40 Years of Progress' (D'Arcy CJ and Burnett PA eds). APS Press, St. Paul, MN. Pp 293-305.

Geske SM, French R, Robertson NL, and Carroll TW. 1996. Purification and coat protein gene sequence of a Montana RMV-like isolate of barley yellow dwarf virus. Arch Virol (In press).

Graybosch RA, Peterson CJ, Baenziger PS, and Shelton DR. 1995. Environmental modification of hard red winter wheat flour protein composition. J Cereal Sci 22:45-51.

Graybosch RA, Peterson CJ, Shelton DR, and Baenziger PS. 1996. Genotypic and environmental modification of wheat flour protein composition in relation to end-use quality. Crop Sci 36:296-300.

Gustafson VS, Baenziger PS, Wright MS, Stroup WW, and Yen Y. 1995. Isolated wheat microspore culture. Plant Cell Tissue and Organ Culture 42:207-213.

Gustafson VD, Baenziger PS, Mitra A, Kaeppler HF, Papa CM, and Kaeppler SM. 1995. Electroporation of wheat anther culture-derived embryoids. Cereal Res Commun 23:207-213.

Moreno-Sevilla B, Baenziger PS, Peterson CJ, Graybosch RA, and McVey DV. 1995. The 1BL/1RS translocation: agronomic performance of F3-derived lines from a winter wheat cross. Crop Sci 35:1051-1055.

Moreno-Sevilla B, Baenziger PS, Shelton DR, Graybosch RA, and Peterson CJ. 1995. Agronomic performance and end-use quality of 1B vs. 1BL/1RS genotypes derived from winter wheat `Rawhide'. Crop Sci 35:1607-1612.

Park WJ. 1995. Effect of polyphenol oxidase on discoloration of rolled noodle products. Ph.D. Dissertation. Department of Food Science and Technology, University of Nebraska-Lincoln. 214 pp.

Park WJ and Shelton DR. 1995. Investigation of Asian rolled noodle discoloration relative to agronomic characteristics, polyphenol oxidase levels, and proximate analyses. Cereal Foods World 40:648 (Abstract).

Park WJ, Shelton DR, and Caines A. 1995. Development of a small-scale laboratory noodle fryer for instant fried noodles. Cereal Foods World 40:667 (Abstract).

Park WJ, Shelton DR, Kachman SD, and Walker AE. 1995. Optimization of temperature and pH for polyphenol oxidase assay in wheat using response surface methodology (RSM). Cereal Foods World 40:650 (Abstract).

Park WJ and Shelton DR. 1995. Development of a small-scale laboratory sheeted noodle dough mixer. The 20th Hard Red Winter Wheat Workers Conference, Oklahoma City, OK (Abstract).

Peterson CJ and Busch RH. 1995. International Germplasm Exchange: Status and Future. In: Proc North American Wheat Workers Workshop (Peterson CJ ed), March 6-8, 1994, Kansas City, MO. National Wheat Improvement Committee, May, 1995. Pp. 93-112.

Peterson CJ (Ed). 1995. Proceedings of the North American Wheat Workers Workshop. March 6-8, 1994, Kansas City, MO. National Wheat Improvement Committee, May, 1995. 214 pages.

Poggi PG, Giunchedi L, French R, Langenberg WG, and Delogu G. 1995. Polymerase chain reaction identification of barley yellow mosaic virus and barley mild mosaic virus. Phytopath Medit 34:114-119.

Salm NS, Rey MEC, and French R. 1996. Molecular cloning and nucleotide sequencing of the 3'-terminal region of a South African isolate of ryegrass mosaic virus RNA and in vitro expression of the coat protein gene. Arch Virol (In press).

Seo YW, Graybosch RA, Peterson CJ, and Shelton DR. 1995. Assessment of enzyme-linked immunoassay of rye secalins as a tool in the prediction of 1RS wheat quality. Cereal Chem 72:252-254.

Watkins JE, Rutledge SE, and Baenziger PS. 1995. Virulence patterns of Puccinia recondita f. sp. tritici in Nebraska during 1992 and 1993. Plant Dis 79:467-470.

Wiess A, Budak N, and Baenziger PS. 1995. Using transpiration to characterize plant height in winter wheat in different environments: A simulation study. Can J Plant Sci 75:583-587.

Worrall WD, Marshall DS, Caldwell SP, Peterson CJ, Baenziger PS, and Schmidt JW. 1995. Registration of Siouxland 89 Wheat. Crop Sci 35:1223.

Yang G, Wehling RL, Zeece MG, Partridge JE, and Shelton DR. 1995. NOTE: Characterization of hard red winter wheat storage proteins by two-dimensional electrophoresis, and their correlations with selected quality parameters. Cereal Chem 72:568-570.

Yen Y, Morris R, and Baenziger PS. 1995. Genome analysis in wheats: History and current status. In: Methods of Genome Analysis in Plants: Their Merits and Pitfalls (Jauhar PP ed). CRC Press, Boca Raton, FL, USA. Pp. 359-373.