ITEMS FROM THE UNITED STATES

SOUTH DAKOTA

SOUTH DAKOTA STATE UNIVERSITY AND THE USDA-ARS NORTHERN GRAIN INSECT RESEARCH LABORATORY (NGIRL).
Plant Science Department, Brookings, SD 57007 U.S.A.

Winter wheat breeding and genetics. [p. 256-258]

A.M.H. Ibrahim, M.A.C. Langham, S.A. Kalsbeck, R.S. Little, F. Hakizimana, and D. Gustafson.

Personnel changes. Dr. Amir Ibrahim joined the Faculty of Plant Science Department as the winter wheat breeder and assistant professor of plant science in June 2000. His master's degree in crop production came from the American University of Beirut, Lebanon, and his doctorate in plant breeding and genetics from Colorado State University, Fort Collins. Following graduate studies, he remained at CSU as a postdoctoral fellow, breeding drought-resistant spring wheat. His research efforts at SDSU focus toward the development of improved cultivars adapted for production in South Dakota and the northern Plains along with other aspects of winter wheat breeding and genetics research.

Crop report. Winter wheat production in 2001 was estimated at 11.8 million bushels from 0.37 million harvested acres (1.3 million planted acres), for an average of 32 bushels/acre, an 80 % reduction compared to 1998. Overall, colder than normal temperatures, very dry autumn planting conditions, loss of snow cover during the winter, and cold late spring resulted in significant acreage loss. The nurseries at Dakota Lakes, in addition to the Crop Performance Trial at Platte, were abandoned.

Breeding program. In 2001, the winter wheat breeding program conducted testing at 11 sites throughout South Dakota. These environments included both Aurora and Brookings (Brookings Co.), Britton (Marshall Co.), Platte (Douglas Co.), Highmore (Hyde Co.), (Selby (Walworth Co.), Winner (Tripp Co.), Wall (Pennington Co.), the Northeast Research Farm near Watertown (Codington Co.), and both irrigated and dryland environments at the Dakota Lakes Research Farm east of Pierre (Hughes Co.). Crop performance testing also was conducted at an additional eight sites west of the Missouri River in coöperation with Clair Stymiest and John Rickertson (SDSU West River Agricultural Research and Extension Center, Rapid City). Crossing and germ plasm enhancement efforts continue to address HRWW and HWWW, end-use quality, and important constraints facing producers in the northern Great Plains (FHB, WSMV, leaf and stem rust, leaf spotting diseases, and winter hardiness). Ongoing research support projects include screening for resistance or tolerance to Fusarium head blight, WSMV, and genetic studies of WSMV inheritance.

Foundation seed increases. Two advanced experimental lines are under foundation seed increase. These lines, SD97457 (Tomahawk/Bennett) and SD97W604 (SD89333 (Gent/Siouxland)//Abilene) are being increased for possible release in autumn 2002 and 2003, respectively. Two lines were placed under small-scale increase for the autumn of 2001 planting season. These lines SD92107-5 (Brule//Bennett/Chisholm/3/Arapahoe) and SD97W609 (Abilene/Karl) have shown promise in regional and statewide trials for the last 2 years.

Inheritance of resistance to WSMV in OK65C93-8 winter wheat line (Hakizimana, Langham, and Ibrahim). Frederic Hakizimana has completed last third of his research studies on WSMV. The main goal of this study was to determine the mode of inheritance and the type of gene action of WSMV resistance in three crosses involving two susceptible and one resistant winter wheat lines. Results indicated that one major single recessive gene and one single dominant gene control the resistance to WSMV in OK65C93-8 winter wheat line. Additive, dominance, and epistatic effects were all found to be involved in the inheritance of WSMV resistance. Narrow-sense and broad-sense habitability estimates were intermediate to high.

Fusarium head blight (Ibrahim and Gustafson). We have established a proactive effort to develop scab-resistant hard winter wheat varieties. Recent changes in winter wheat production practices could lead to an increase in scab (increase in reduced tillage and changes in cropping systems). A mist-irrigated scab evaluation nursery will be used to evaluate elite breeding lines, regional nurseries, commercial varieties, and segregating populations. The winter wheat breeding program at South Dakota State University has screened transplanted hill nurseries for scab resistance since 1999 utilizing an established mist-irrigated field screening nursery designed to test cultivars, elite lines and preliminary lines for resistance to FHB. In 2001, we investigated planting schemes to determine if direct seeded row materials are affected differently than transplanted hill plots when they are inoculated with FHB. Preliminary results suggested that there were indeed significant correlations between the two methods. We will continue to investigate planting schemes in future studies as well as to begin evaluating winter wheat lines and varieties for scab tolerance under greenhouse conditions in 2002.

White wheat (Ibrahim, Little, and Kalsbeck). For the past 5 years, our breeding efforts for HWWW have centered on making crosses between adapted red lines and unadapted white germ plasm. We have been successful at incorporating resistance to prevalent races of stem rust and increasing the winter-hardiness of the hybrid material. We are ready to pursue the more difficult challenges of increasing coleoptile length, decreasing preharvest sprouting susceptibility, and decreasing PPO activity (a predictive measure of noodle-making quality) without sacrificing bread-making qualities.

The new challenges will require efforts at germ plasm development which have heretofore been outside the scope of the SDSU Winter Wheat Breeding Project. We have screened coleoptile length, but have had few successes in increasing the length. Screening for sprouting susceptibility has been conducted for a couple of years with questionable results. Preharvest sprouting resistance is undoubtedly our biggest challenge and will command our most intense efforts at both screening and germ plasm development. In the coming year, we will outline a plan for germ plasm development to meet these challenges.

We are currently focusing on understanding the results of our PPO activity tests and are developing a screening regime for PPO activity. For PPO activity screening, several breeding programs use adaptations of the L DOPA whole-seed or L-DOPA flour tests described by Anderson and Morris (2001). We have used a visual adaptation of the whole-seed test, but have kept selection intensity low because of questions concerning the repeatability of this method. We are now comparing the results of tests for PPO activity in meal, flour and whole seed samples. We also are evaluating the repeatability of a new protocol that combines a meal PPO test with the meal sedimentation test, (a predictive measure of bread-baking quality). Screening during the month between harvest and planting has not been implemented in previous years because of the time crunch. A combined meal and PPO test will enable us to do a limited amount of screening at harvest time with a maximum effect. Screening for high PPO activity prior to planting will perhaps eliminate 40 EYT white lines, 50 PYT white lines and 15 AYT white lines. Screening for sedimentation prior to planting will perhaps eliminate 100 EYT lines, 150 PYT lines, and 8 AYT lines.

Molecular pathogen-wheat interactions and DNA marker development. [p. 258]

Yang Yen, Denghui Xing, Lanfang Bai, Lieceng Zhu, and Yue Jin.

In the year of 2001, our research efforts were focused on 1) identification of pathogen and host genes that play key roles in scab pathogenesis; 2) cloning the Sr25 gene; and 3) implementation of DNA MAS in SD wheat improvement programs. So far, seven ESTs have been observed to be specific to the FHB-inoculated, Sumai 3 spikes in our repeated experiments. These ESTs were cloned and sequenced. A blast search of GenBank with these ESTs as query sequences has revealed no homologue with any known R or PR gene. Northern and Southern hybridizations revealed that two of the cloned ESTs belong to pathogen F. graminearum and the rest are wheat. We are currently cloning the full-length cDNA of the corresponding genes. Eleven ESTs have been identified as being specifically expressed in P. graminis-inoculated wheat line 'Sr25/9*LMPG'. These ESTs are the most promising and the possible ones that are specifically related to stem rust resistance gene Sr25. Our data indicated that Sr25 seems to be expressed about 2 hours after invading wheat tissues. As the first step toward our goal to implement DNA MAS, we screened 78 elite breeding materials from SD spring wheat breeding program and 87 elite selections from USWBSI spring wheat germ plasm program for SSR markers with primer sets gwm533, gwm493, and gwm389. Sumai 3 and Wheaton were used as the controls. The results showed that 38 of the 78 elite breeding lines screened have the Qfhs.ndsu-3BS-gwm493 marker identified by Anderson et al. (2001) but only five also have the Qfhs.ndsu-3BS-gwm533 marker. Of the 87 elite germ plasm selections screened, 27 lines have the Qfhs.ndsu-3BS-Xgwm493 markers, 31 lines have the Qfhs.ndsu-3BS-Xgwm533 marker, and 26 lines have the Qfhs.ndsu-3BS-Xgwm389 marker. The Xgwm533-120bp, Xgwm493-140bp, and Xgwm493-160bp markers observed in our elite-breeding lines also were observed among the elite germ plasm selections. In addition, new markers Xgwm389-130bp, Xdwm533-300bp, and Xgwm533-165bp also were observed among the selections.

Soil N fertility management. [p. 258]

Howard J. Woodard, Anthony Bly, and Dwayne Winther.

The yield and crude protein levels of three varieties of HRSW were tested after the application of 0. 90, 170, and 240 kg N/ha as dry fertilizer. As N rate increased from the control to the highest rate, yield only increased by 250 kg/ha. However, crude protein increased 2.2 % to the 170 kg/ha rate over the control and leveled off thereafter. In another experiment, a foliar application rate of 33 kg/ha was applied to a single HRSW variety at planting (on bare soil), tillering, jointing, and the boot stage. The rate was a supplement to the N rate applied to attain a 3,300 kg/ha yield goal. Crude protein increased by 0.5 % at each application stage compared to the control (no foliar application) , but increased to 1.0 % over the control at the boot stage. There was no yield increase to the foliar application at any application stage.

Cereal aphids, other arthropods, and diseases. [p. 259]

L. Hesler and W. Riedell (USDA-ARS-NGIRL).

Research continues on ways to limit infestations of cereal aphids, other arthropod pests, and diseases in wheat. We are determining the mechanisms and levels of resistance to bird cherry-oat aphids among wheat and related grasses. We also are coöperating with Dr. Marie Langham (SDSU, plant virologist) to determine any effects of staggered dates of planting on insect infestations, incidence of viral diseases, and plant growth and yield of winter and spring wheat at two locations in South Dakota. We are surveying for the multicolored Asian ladybird beetle, which recently arrived in eastern South Dakota, to determine whether it will have any significant impact on cereal aphid populations in small-grain crops. We also are collaborating with Dr. S. Dean Kindler (USDA-ARS-PSWCRL, Stillwater, OK) to develop rearing methods, determine host plant suitability, and characterize plant damage by the rice root aphid, another member of the cereal aphid complex and vector of barley yellow dwarf virus. Dr. Mike Catangui (SDSU, extension entomologist) and Dr. Hesler also have participated in a regional survey for army and pale western cutworms in South Dakota and several other western states. The levels of these cutworms have generally remained low in South Dakota, although some individual fields have had significant infestations in recent years. Finally, Dr. Riedell is cooperating with Drs. Shannon Osborne (USDA-ARS-NGIRL) and Yue Jin (SDSU, wheat pathologist) in evaluating remote sensing technology for detection of rust and tan spot diseases in greenhouse experiments. Field experiments on remote detection of these diseases and others are also being conducted.

Dosage effect of wheat streak mosaic virus on agronomic characteristics of winter wheat lines. [p. 259-261]

Cynthia I. Bergman and Marie A.C. Langham.

Ten lines of winter wheat were evaluated over 2 years for their reaction to dilutions of WSMV. Plants were mechanically inoculated with inoculum dilutions of 1:5, 1:10, and 1:20 (ratio of infected tissue to extraction buffer). Dilution (inoculum dosage) was found to significantly affect the agronomic characteristics of plant height (P = 0.0018), kernel protein analysis (P = 0.0200), spike length (0.0265), kernel number (P = 0.0152), kernel weight (P = 0.0130), and 100-kernel weight (P = 0.0346). These results prove the viral disease resistance expression in winter wheat varieties is affected by dilution (dosage level of inoculum).

Introduction. WSMV, of the family Potyviridae in the genus Tritimovirus, causes a worldwide, economically important wheat disease. Yield losses are estimated to be about 5 % annually with up to 100 % loss in localized areas. Leaf symptoms of the disease move progressively from a faint light green mottle (mosaic), dots, or dashes to a yellow (chlorotic) mottling, then broken streaking, and finally into long, linear streaking. In advanced or severe cases, the leaf streaking becomes severely chlorotic, then necrotic, until the leaves and ultimately the plant dies. Other symptoms are stunted roots, reduced plant height, failure to produce heads, and poor grain. Heads often contain shriveled kernels, which lower kernel size and weight as well as the number of kernels per head. Test weights and yield are both reduced. The inoculum dilutions used by researchers to infect test plots of wheat have varied widely, ranging from 1:1 to 1:50. This experiment was designed to test if the dosage level used in screening nurseries affected their level of resistance to WSMV.

Materials and methods. The 10 winter wheat lines utilized were Arapahoe (PI 518591), Dawn (CI17801), Jagger (PI593688), Harding (PI608049), KS95-H102, KS96HW10-1, Sage (CI17277), SD93267, TAM 107(PI495594), and Vista (PI562653). The inoculum for this experiment was a WSMV originally collected from infected wheat plants in South Dakota. Presence of virus in all inoculated plots was verified with serological methods.

Results. Dilution had a significant effect on the agronomic characteristics of plant height (0.002), protein (0.02), head length (0.03), kernel number (0.02), kernel weight (0.01), and 100-kernel weight (0.03). In all six tables, significant differences (0.05 or less) are marked with an asterisk (*), and highly significant differences (0.01 or less) are marked (**).

Summary. Inoculum dilution affects virus resistance through the plant's disease expression. These results prove WSMV inoculum dilution rates affect disease resistance ratings. Variations in the means of the lines used indicates that dosage had varying effects on characteristics; because of this reaction to dilution, classifying varieties as resistant based solely on yield, stunting, or viral content is likely to miss resistance genes present in lines strong in other characteristics. For wheat breeders, this means low levels of resistance to WSMV may be found in previously overlooked wheat lines by screening with several different inoculum dilutions before labeling a plant with a simple yes or no for resistance.

Acknowledgments. Agricultural Experiment Station at South Dakota State University, South Dakota State University Wheat Breeding Program, South Dakota Crop Improvement Association, and South Dakota Wheat Commission.