University of California
Department of Botany and Plant Sciences, Riverside, CA 92521-0124, USA. Bahman Ehdaie, Adam J. Lukaszewski, Rana Tayyar, X. Xu, and J. Giles Waines.
Components of water-use efficiency in bread wheat. We suggested two models to facilitate the study of genetic variation for seasonal water-use efficiency (WUE, ratio of grain yield to evapotranspiration water) and its components in spring bread wheat (Ehdaie and Waines 1993). The two primary components of WUE were defined as evapotranspiration efficiency (ETE, total dry matter/evapotranspiration water) and harvest index (HI, grain yield/total dry matter). Our results, in a replicated pot experiment with eight wheat cultivars, indicated that HI and ETE accounted for 85 % and 15 % of variation in WUE under well-watered conditions and for 81 % and 19 % under droughted conditions, respectively. Carbon isotope discrimination showed negative correlation with ETE in well-watered (-0.82) and droughted (-0.68) conditions. Analysis of two different sets of published data (Siddique, Tennant, Perry, and Belford 1990; Condon, Richards, and Farquhar 1993) indicated that uptake efficiency (UE, ratio of transpired water/evapotranspiration water) contributed only from 2 to 5 % of variation in WUE among the wheat genotypes grown under droughted field conditions. In contrast, the contribution of transpiration efficiency (TE, ratio of shoot dry matter to transpired water) was from 27 to 65 % and that of HI was 31 to 68 %, depending on genotypes and environmental conditions. (Ehdaie and Waines)
Genetic variation of nitrogen-use efficiency in bread and macaroni wheat. Wheat cultivars with improved nitrogen-use efficiency (NUE) are desirable. Progress in developing wheat cultivars that can absorb N more efficiently from the soil and partition most of the absorbed N into grain depends upon genetic variation for NUE and its components. In the 1993/94 season, 15 bread and macaroni wheat cultivars were planted in the field under three levels of N application at two different dates of plantings. Nitrogen contents of plants at anthesis and at maturity and of grains are being determined. (Ehdaie and Waines)
Chromosomal locations of genes controlling water-use efficiency in Chinese Spring bread wheat. Twenty-four ditelocentric (half chromosome) lines of Chinese Spring and the Chinese Spring euploid line were grown in a replicated pot experiment in the glasshouse under well-watered conditions in 1994. The amount of water used during the experiment, total dry matter, and grain yield were measured. From these measurements, water-use efficiency (WUE = grain yield/water used), evapotranspiration efficiency (ETE = total dry matter/water used), and harvest index (HI = grain yield/total dry matter) will be determined. In the 1995 season, the remaining ditelocentric lines (18) in this series are being grown under similar conditions. The complete data will be subjected to ditelocentric chromosome analysis to locate genes influencing ETE, HI, and WUE. (Ehdaie and Waines)
Biodiversity in weedy goat grasses and wild wheats. While motoring from Antakya to Kilis in southern Turkey in 1990, I observed a site close to the Syrian border where diploids Aegilops speltoides and Ae. umbellulata and tetraploid Ae. triuncialis grew. Also present was a taxon that superficially looked like Ae. triuncialis, but where the glumes of the spikelets had a broad triangular tooth and a single awn, which formed a wide angle with the axis of the spike. Several plants of this taxon were present. I thought it might be a new botanical variety of Ae. triuncialis or possibly a new taxon. In May 1994, near the village of Abeen, Aleppo province, northwestern Syria, Dr. Jan Valkoun, Genetic Resources Unit, ICARDA, and I came across the same taxon. It grew at the side of the road, the base of which was made of limestone chips, with Ae. speltoides and Ae. biuncialis growing nearby. So this new variety or taxon has a local distribution spanning the Syrian-Turkish border. In May 1994, between the villages of Abeen and Dier Jamal, Aleppo province, northwestern Syria, Dr. Valkoun and I also observed a hairy form of wild tetraploid wheat T. turgidum ssp. dicoccoides, growing with smooth spp. dicoccoides, T. urartu, and T. monococcum spp. boeoticum. The stems of this new form have long hairs, even though the leaves are not very hairy. Japanese botanists have reported the hairy wild tetraploid T. timopheevii ssp. araraticum growing just north of the Syrian-Turkish border between Kilis and Gaziantep in southern Turkey. These two sites are less than 40 km apart, which suggests that T. timopheevi ssp. araraticum may also be present in Aleppo province. The identity of these two taxa is under investigation. (Waines)
Wheat cytogenetics. The initial round of screening and seed increase of the E.R. Sears collection of aneuploids of Chinese Spring (CS) wheat has been completed. Several problems have been identified, which include the presence of translocations and deficiencies in some stocks and missing lines in some sets, particularly in the double monosomics with 5B and the diisosomics. These problems are being addressed slowly, time and greenhouse space permitting. Currently, the E.R. Sears collection of CS aneuploids consists of about 600 entries, with 229 aneuploids, 58 alien addition lines, 37 alien translocation lines, 63 intervarietal and 22 alien substitution lines, 11 mutants, and about 80 deficiency stocks. Six of the original telocentric chromosomes available in Chinese Spring were not obtained by misdivision of CS chromosomes, but were first found in other wheats and transferred to CS by backcrossing. These telocentrics are: 2BS, 2DL, 4AS, 5DS, 6AL, and 7DL, of which 4AS was, and 5DS was believed to be, acrocentric. Non-CS origin of these six chromosomes appears to create problems in some research, with 7DL collecting the highest number of complaints. To remedy the problem, attempts are being made to produce new telocentrics from CS chromosomes. So far, a true telo 4AS and telo 6AL have been produced with the former already available in 20" + 4AS", 20" + 4AS" + 4AL' and DDt 4A lines. A centric translocation, 7DS-4Rlm, involving the long arm of chromosome 4R of Secale montanum from hexaploid triticale, PI386148, has been produced in Pavon wheat. Chromosome arm 4RLm carries a gene for virtual immunity to the Russian wheat aphid. The 7DS-4RLm translocation was expected to be noncompensating and, consequently, to have reduced fertility. Surprisingly, under greenhouse conditions the seed set on translocation homozygotes was slightly higher than on their normal, nontranslocated sibs. Translocation homozygotes are being evaluated currently for agronomic performance under field conditions, courtesy of Dr. P.S. Baenziger and are being reevaluated for their RWA resistance, courtesy of Dr. C. Baker. Appropriate genetic stocks of Pavon wheat are being constructed to induce homoeologous recombination between 4RLm and corresponding homoeologous wheat chromosome arms. Using a series of ph1b-induced homoeologous recombinants of chromosome 7S of Ae. speltoides with chromosome 7A of Pavon wheat, a greenbug resistance gene, Gb5, was localized in the distal region of the long arm of 7S, about 75 % of the relative arm's length away from the centromere. Following the screening for the presence of Gb5 by Dr. K. Porter of USDA-ARS, Stillwater, OK, two reciprocal recombinant chromosomes carrying Gb5 were identified, combined in one plant, and backcrossed to normal wheat. It is expected that chromosome 7A with a small intercalary segment of chromosome 7S from Ae. speltoides with Gb5 will be isolated this spring. By a combination of centric misdivision of univalents and the chromatid type breakage-fusion-bridge cycle initiated by reverse tandem duplications in meiosis, a series of midget chromosomes was produced from the long arm of chromosome 1B in Chinese Spring wheat. These midget chromosomes cover the entire long arm of 1BL. (Lukaszewski, Tayyar, Xu)
Triticale genetics and cytogenetics. A set of 147 hexaploid winter triticale lines from breeding programs in Europe (Bulgaria, Slovakia, France, Germany, Hungary, Poland, Rumania, Sweden, Switzerland, and former Soviet Union) and North America (Canada and USA) were screened by Acid-PAGE and SDS-PAGE for their allelic composition at the Gli-1 and Glu-1 loci. Wide heterogeneity, but relatively little heterozygosity, of allelic constitution was observed in most samples. No relationship between the high molecular weight glutenin subunits or gliadin alleles and micro SDS-sedimentation value was observed. However, several triticale lines with SDS-sedimentation values over 60 % that of a wheat check were identified. These lines appear to be the prime candidates to receive the 1R-1D and 1A-1D translocations with the d allele of the Glu-D1 gene. (Lukaszewski, Brzezinski, Rybalka)
Publications. Ehdaie B and Waines JG. 1993. Variation in water-use efficiency and its components in wheat: I. Well-watered pot experiment. Crop Sci 33:294-299. Ehdaie B and Waines JG. 1994. Genetic analysis of carbon isotope discrimination and agronomic characters in a bread wheat cross. Theor Appl Genet 88:1023-1029. Ehdaie B and Waines JG . 1994. Growth and transpiration efficiency of near-isogenic lines for height in a spring wheat. Crop Sci 34:1443-1451. Lukaszewski AJ. 1994. Genetic mapping in the 1R-1D wheat-rye translocated chromosomes. Genome 37:945-949. Lukaszewski AJ. 1995. Physical distribution of translocation breakpoints in homoeologous recombinants induced by the absence of the Ph1 gene in wheat and triticale. Theor Appl Genet (In press). Lukaszewski AJ and Xu X. 1995. Screening large samples of wheat hybrids by C-banding. Cereal Res Commun (In press). Waines JG. 1994. High temperature stress in wild wheats and spring wheats. Aust J Plant Physiol 21(6):In press.
Colorado State University
Department of Agronomy, Fort Collins, CO 80523, USA. J.S. Quick, J. Stromberger, B. Clifford, S. Clayschulte, H. Dong, and Q.A. Khan.
Production. The 1994 Colorado winter wheat production was 76.5 million bushels, down 19 % from the 1993 crop, and the yield average was 30 bu/acre, down from 37 bu/acre in 1993. Major limiting factors were extremely dry conditions during grain filling and Russian wheat aphid damage on about 25 % of the acreage. Leading cultivars were TAM 107, Lamar, Baca, and Yuma.
Breeding program. Three new cultivars were released in 1994; Akron and Halt are HRW wheats, and Sylvan is a HRS wheat. Akron is a semidwarf with very lax spikes. Compared to current cultivars, it has higher yield, hail tolerance, leaf rust tolerance, and excellent quality. Halt is the first Russian wheat aphid (RWA)-resistant wheat developed in the USA. It is an early semidwarf with excellent quality, is moderately susceptible to leaf rust, and is slightly lower yielding than Yuma. Sylvan is a semidwarf hard red spring developed in Utah and has an 11 % yield advantage over other wheats when grown under irrigation in southwestern Colorado. Selection progress was made for grain yield, grain volume weight, winter hardiness, resistance to shattering, drought tolerance, WSMV resistance, and bread-making quality. Cultivar performance trials and Russian wheat aphid evaluations were conducted statewide.
Russian wheat aphid. Field studies to determine the economic injury level on a resistant wheat line were conducted at Fort Collins in 1992, 1993, and 1994. RWA infestations resulted in significant yield reduction on susceptible wheat, but not on the improved resistant wheat. The first uniform RWA field screening test confirmed greenhouse screening test results, showing that resistance levels of many new lines equal those of the resistant parents and that a significant association exists between grain yield and RWA resistance. At least seven different major genes have been associated with RWA resistance. We have completed genetic studies on 14 resistant lines by crosses to a susceptible parent and by crosses to three resistant wheats previously characterized for gene(s) for resistance. Early generation among-cross selection for chemical desiccation tolerance and the associated use of mechanical mass selection were studied. A cross between tolerant parents showed lower desiccation injury than crosses between sensitive parents or among contrasting parents. Mechanical mass selection within populations advanced with two cycles of chemical desiccation produced F4-bulk populations with significantly lower desiccation injury.
Personnel. During the past 18 months, the wheat project has hired three new technicians due to retirements and financial reallocation, John Stromberger replacing Gerry Ellis, Bruce Clifford replacing Ron Norman, and Sally Clayshulte as a new position.
Publications. Dong H, Nkongolo K, and Quick JS. 1994. Progress and problems in the transfer of Russian wheat aphid resistance from Russian triticales to wheat. Proc Sixth Russian Wheat Aphid Workshop, Fort Collins, CO. Dong H and Quick JS. 1994. Inheritance and allelism of Russian wheat aphid resistance in a group of wheat lines. Agron Abstr:109. Haley SD and Quick JS. 1993. Early generation selection for chemical desiccation tolerance in winter wheat. Crop Sci 33:1217-1223. Kroening M, Hammon R, Armstrong S, Peairs F, and Quick JS. 1994. Economic impact of Russian wheat aphid on resistant and susceptible wheats in Colorado. Proc Sixth Russian Wheat Aphid Workshop, Fort Collins, CO. Quick JS. 1994. Annual Wheat Newsletter Vol. 40. 380 p. Quick JS. 1994. Development of cultivars resistant to the Russian wheat aphid. Proc Sixth Russian Wheat Aphid Workshop, Fort Collins, CO. Quick JS and Dong H. 1994. First uniform Russian wheat aphid field test. Proc Sixth Russian Wheat Aphid Workshop, Fort Collins, CO. Randolf T, Holtzer T, Peairs F, and Quick JS. 1994. Tritrophic relationships: a comparison of TAM 107 and CORWA1 winter wheat varieties with Russian wheat aphid and Hippodamia variegata. Proc Sixth Russian Wheat Aphid Workshop, Fort Collins, CO. Saidi A and Quick JS. 1994. Inheritance of Russian wheat aphid resistance in four winter wheats. Proc Sixth Russian Wheat Aphid Workshop, Fort Collins, CO.
Georgia Experiment Station
Experiment, GA 30212, USA. J.W. Johnson, B.M. Cunfer, J.J. Roberts, G.D. Buntin, and D.E. McMillin. The 1994 Georgia winter wheat crop was grown on about 500,000 harvested acres and produced a state record yield of 52 bushels per acre. Yields were obtained as high as 6,000 kg/ha with test weights over 73 kg/hl. Excellent planting conditions in November resulted in a well established stand, and good winter conditions were conductive to excellent tillering. Weather conditions during late January to early March were nearly perfect for topdressing. Temperatures remained cold at night, while days were cool, bright, and sunny. During the grain filling period, diseases were not major factors.
Cultivars. Two early maturity (GA-Stuckey and Morey) and a full season (GA-Dozier) soft red winter wheat cultivars were developed and jointly released by the University of Georgia Agricultural Experiment Station and USDA-ARS, and Florida Agricultural Experiment Station. GA-Stuckey was derived from a double cross in 1983: MD 73055/GA 73-1-2-5//`Coker 797`/`Caldwell`. It was named to honor Dr. Stuckey, the former Resident Director for the Georgia Station, Griffin. The cultivar was developed using a modified pedigree method of breeding and was evaluated for agronomic performance as GA 83228. GA-Stuckey is early maturing, short at maturity, white chaffed, awnless, and characterized by intermediate straw strength with high yield potential. During 3-yr tests (five locations/yr) in Georgia, GA-Stuckey and `GA-Andy` yielded averages of 4,018 and 3,999 kg ha-1, respectively. It is 1 day later than GA-Andy in maturity, and has similar test weight. Milling and baking quality characteristics of GA-Stuckey are rated as excellent for soft red winter wheat use by the USDA-Soft Wheat Quality Laboratory, Wooster, OH. Morey was developed cooperatively and released by the Georgia and Florida Agricultural Experiment Stations in 1994. Morey was derived from a single cross made in 1985 at the University of Florida: 'FL8172-G116/Florida 303`. FL8172-G116 is a sister line to 'FL 304'. It was named to honor Dr. D.D. Morey, the former wheat breeder at the Coastal Plain Station, Tifton. The cultivar was developed using a modified pedigree method of breeding. Morey was tested experimentally as GA 85238-C5-AB5-4. Morey is very early maturing in the Southeast. It is medium height at maturity, white-chaffed, awned, and characterized by good straw strength with high yield potential. During 2-yr tests (5 locations/yr) in Georgia, Morey, `Andy`, and FL 304 yielded averages of 3,531; 3,424; and 3,524 kg/ha; respectively. It is about 5 days earlier in maturity and 8 cm shorter than Florida 304 and has excellent lodging resistance. Milling and baking quality characteristics of Morey are rated acceptable for soft red winter wheat use by the USDA-Soft Wheat Quality Laboratory, Wooster, OH. GA-Dozier was developed at the University of Georgia Agricultural Experiment Station in cooperation with the USDA-ARS and released in 1994. GA-Dozier was derived from a single cross in 1984: `Saluda`/`Coker 797`. It was named to honor Hugh Dozier, the former research assistant for the breeding program for over 25 years at the Georgia Station, Griffin. The cultivar was developed using a modified pedigree method of breeding. GA-Dozier was evaluated for agronomic performance as GA 84438. GA-Dozier is late maturing, short at maturity, white chaffed, awned, and characterized by excellent straw strength with high yield potential. During 4-yr tests (five locations/yr) in Georgia, GA-Dozier and `GA 100` yielded averages of 4,404 and 3,810 kg/ha, respectively. It is 1 day earlier than Saluda in maturity and has lodging resistance similar to GA 100. Milling and baking quality characteristics of GA-Dozier are rated as excellent for soft red winter wheat use by the USDA-Soft Wheat Quality Laboratory, Wooster, OH. GA-Stuckey, GA-Dozier, and Morey are resistant to the biotypes E, G, M, and O of Hessian fly (Mayetiola destructor(Say)) present in Georgia and Florida, resistant to current races of leaf rust caused by Puccinia recondita (Rob. ex Desm.), and powdery mildew caused by Erysiphe graminis DC. f. sp. tritici Em. Marchal. A barley cultivar (Acton) that possesses the unique resistance for barley to Hessian fly, was released in 1994. The barley line, GA-81814, with excellent yielding potential and resistance to scald is being increased for possible release in 1995.
Waterlogging. Understanding plant responses to hypoxia and subsequent resumption of aeration is important for breeding tolerant genotypes. Plants were grown for 14 and 21 d in nutrient solutions flushed with air or with a mixture of O2 and N2 or hypoxia for 14 d followed by aeration for 7 d (recovery). Shoot and root growth was inhibited by hypoxia with roots being more sensitive. The growth responses of six wheat genotypes to waterlogging and subsequent recovery showed that the adverse effect of hypoxia was most severe for Bayles and Fl 302, intermediate for Coker 7966 and BR 34, and least for Gore and Savannah. Anatomical, physiological, and growth responses of two wheat genotypes revealed that waterlogging reduced photosynthesis and shoot and root growth for both tolerant and sensitive genotypes. Waterlogging enhanced the formation of aerenchyma in the cortical tissue of roots and to a greater extent for Savannah. Increase in nutrient supply to waterlogged plants could alleviate some of the adverse effects. Seven days after resumption of aeration, shoot growth recovered completely for Gore and Savannah but only partially for Bayles, Fl 302, BR 34, and Coker 9766. Breeding for waterlogging tolerance could be facilitated by selecting genotypes that develop more crowns roots and more aerenchyma in those roots.
Plant Pathology. Isolates of the wheat and barley biotypes of Stagonospora nodorum, from a wide geographical range in the eastern U.S., were compared on the basis of biological characters and by RFLP analysis. Genetic similarity was very high within each biotype and very low between the two biotypes that correlated with the biological differences. Based on allele frequencies of 31 RFLP loci, the genetic distance between the two biotypes was as great as their distance from S. avenae f. sp. triticea. Analysis of discrete hybridizing bands indicated that the barley biotype is related more closely to S. avenae f. sp. tritici than to the wheat biotype of S. nodorum. The late fall and early winter of 1993-94 were colder than normal, but there was no significant cold damage during the season. As a result, powdery mildew, leaf rust, and barley yellow dwarf were low in severity. A survey for BYD in 30 fields detected only trace amounts when assayed by ELISA at milk stage. This was in contrast to the previous season when 28% of leaves tested had BYDV. Damage from S. nodorum was generally low.
Cereal Rust Lab. Eleven years of expanded Southeast cereal rust epidemiology research and surveys have monitored and documented several rapid changes in wheat leaf rust virulence in response to deployment of new genes for resistance. Recently detected races often dominate the leaf rust population in only 1 to 2 years, forcing either changes in cultivar use or major fungicide use. Because these virulence shifts by the exceptionally plastic rust pathogens continue to limit the effective life of new cultivars, efforts to find and utilize new genes for rust resistance are essential. The first cycle of Ceruga rust-resistant germplasm lines have been available for some time. They feature novel sources of rust resistance that have not been used widely in the Southeast until now. Twelve new Ceruga germplasm lines have been submitted for release approval and offer several new sources of leaf rust resistance in promising agronomic types. The eighth year of the interstate highway trap nursery epidemiology research and survey technique supplies incidence, severity and virulence information to supplement standard survey data. This technique is also well-suited for monitoring powdery mildew, Septoria, and virus diseases and for detecting disease-vectoring cereal aphids. The relatively ephemeral nature of protection afforded by genes for leaf rust resistance highlights the need for expanded research to identify and use other types of resistance to cereal rusts, particularly those types not characterized by vulnerability to race changes. Combo wheat, a germplasm line with dense leaf pubescence has been observed in preliminary nursery trials in the Southeast to evaluate its effectiveness in controlling wheat pests. It is adapted to the Region well enough to be used in detailed experiments. Greenhouse and laboratory data indicate control levels in the 30 % range are possible for leaf rust on pubescent versus glabrous leaves.
Publications. Cunfer BM. 1994. Biology and nomenclature of Septoria and Stagonospora species on cereals. In: Proceedings of the Fourth International Workshop on Septoria of Cereals. IHAR, Radzikow, Poland. Pp. 15-18. Huang B, Johnson JW, NeSmith DS, and Bridges DC. 1994. Growth, physiological and anatomical responses of two wheat genotypes to waterlogging and nutrient supply. J Exp Bot 45(193):202. Huang B, Johnson JW, NeSmith DS, and Bridges DC. 1994. Root and shoot growth of wheat genotypes in response to hypoxia and subsequent recovery. Crop Sci 34:1538-1543. Johnson JW and Huang B. 1994. Responses of triticale to hypoxia. Proc 4th Inter Triticale Symp, Lisbon, Portugal. Johnson JW, Buntin GD, Cunfer BM, Roberts JJ, and Bland D. 1995. Registration of GA-HFB Hessian fly resistant barley germplasm line. Crop Sci 35:294-295. Long DL and Roberts JJ. 1994. Utilizing a large database to study leaf rust race and virulence gene distribution. Phytopathology 84:(Abstract). Long DL, Roelfs AP, Leonard KL, and Roberts JJ. 1994. Virulence and diversity of Puccinia recondita f. sp. tritici in the United States in 1992. Plant Dis 78:901-906. McCracken DV, Box JE, Hargrove WL, Cabrera ML, Johnson JW, and Raymer PL. 1994. Nitrate leaching in response to tillage and cover cropping practices. In: Proc 13th International Soc Soil Tillage Res Conf, Aalborg, Denmark. 24-29 July. Mmbaga MT, Steadman JR, and Roberts JJ. 1994. Effect of leaf pubescence on urediniospore deposition, germination and infection density of bean rust (Uromyces appendiculatus). Ann Appl Biol Vol. 125. Roberts JJ and Fowler HA Jr. 1994. Cereal rust epidemiology studies using roadside trap plots in the southeastern United States. Plant Dis 78:306-308. Roberts JJ, Hoogenboom G, and Ford PB. 1994. Utilization of research findings and databases for serendipitous technology transfer. Comput Electron Agric 10:75-82. Ueng PP, Cunfer BM, Bergstrom GC, and Chen W. 1994. Differentiation and identification of Stagonospora nodorum and S. avenae using restriction fragment length polymorphisms. In: Proc Fourth Inter Workshop on Septoria diseases of Cereals. IHAR, Radzikow, Poland. Pp. 39-41. Ueng PP, Cunfer BM, Alano AS, Youmans JD, and Chen W. 1995. Correlation between molecular and biological characters in identifying the wheat and barley biotypes of Stagonospora nodorum. Phytopathology 85:44-52. Wilkinson RE and Roberts JJ. 1994. Barriers in the wheat leaf rust preinfection phase. In: Plant-Environmental Interactions (Wilkinson RE ed) Marcel Decker Inc., New York, NY. Pp 555-599.