Departments of Agronomy, Entomology, and Botany and Plant Pathology, and the USDA-ARS, Purdue University, West Lafayette, IN 47907, USA.
J.M. Anderson (USDAARS), I.M. Dweikat, T. Kisha, H.W. Ohm, and F.L. Patterson, and H.C. Sharma (Department of Agronomy); G. Buechley, S. Goodwin (USDAARS), D. Huber, K. Perry, D.G. Schulze, I. Thompson, and G. Shaner (Department of Botany and Plant Pathology); R.H. Ratcliffe, R. Shukle, C.E. Williams, C. Collier (USDAARS, Crop Production and Pest Control Research Unit), S. Cambron, L.M. Gumaelius, C. Linag, L. Zantoko, and J. Stuart (Department of Entomology).
Indiana farmers harvested 650,000 acres (263,000 ha) of SRWW in 1998, at an average yield of 55 bu/acre (3,451 kg/ha), for a total production of 35.75 million bushels (0.907 million metric tons). Total production in 1998 was 93.3 % of the production in 1997. Patterson, in its second year of production, was the leading public cultivar, occupying 16.7 % of the wheat area, up from 9.4 % of the wheat area in 1997. Public cultivars, identified by cultivar name, occupied 36.5 % of the wheat area; private cultivars and brands, including some publicly developed lines marketed under license agreements, occupied 63.5 % of the wheat area.
Five SRWW cultivars were released. Seed of these new cultivars will be available to farmers for planting in autumn 1999. Their temporary breeding designations are shown in parentheses, and their most important traits are listed. Goldfield (P89118RC1-9-3-3) heads 3 days later than Patterson at Lafayette , has low incidence of FHB, has resistance to glume blotch, and is very winterhardy. INW9811 (P86958RC4-2-1-10) heads early like Patterson at Lafayette, has resistance to glume blotch, and has Hessian fly resistance-gene H13. INW9853 (P88288C1-6-1-2) heads 4 days later than Patterson, has low incidence to FHB, and has resistance to glume blotch. INW9812 (P88288A1-15-1-4) heads early like Patterson and has glume blotch resistance. INW9824 (P92823A1-1-4-4-5) heads 1 day later than Patterson and has one gene for type 2 resistance to FHB from cv Ning 7840.
Weather and disease summary.
Wheat seeding normally is completed by the end of October, but continued through November 1997 because of warm temperatures. Wheat, normally dormant by early December, grew until the end of December, resulting in more than optimal growth in wheat seeded in early to mid October. Temperatures throughout the winter months were unusually warm due to the influence of the El Niño weather pattern. Wheat resumed growth by late February, 2 to 3 weeks earlier than normal, and continued to be at least 2 weeks earlier than normal to harvest. Crop growth was excellent early in the season, but by early June, the crop condition began to decline due to excessive moisture and diseases, particularly powdery mildew and glume and leaf blotches. Fusarium head blight was moderate to severe in many areas in southern Indiana but was negligible generally north of Indianapolis. Grain test weight and quality were reduced by diseases and rainy weather in some areas of Indiana during harvest.
Barley yellow dwarf virus.
H.C. Sharma, J.M. Anderson, and H.W. Ohm.
ELISA of hybrids between our BYDV-resistant addition lines, P25 and P114, and the Th. intermedium addition line L1 developed in France, showed that these most likely have the same genes, because the ELISA values of the hybrids were the same as those of the disomics. However, dot blot analysis of the lines and chromosome pairing in the hybrids showed that the group-7 chromosome from Th. intermedium in L1 is not the same as the one in the Purdue lines. Probe pAW161, which specifically hybridized to the long arm telomere of the Th. intermedium chromosome in P29, hybridized to genomic DNA of P29, but not to genomic DNA of wheat or L1. The hybrids averaged 1.21 to 2.09 univalents per cell.
To determine if there is enhanced resistance to PAV isolates of the virus exists in hybrids among group 7, group 2, and group 1 chromosomes of Th. intermedium, hybrids among these addition lines were produced. Simultaneously, seeds of monosomic addition lines for groups 2 and 1 were produced and irradiated to induce translocations.
Anther culture and interspecific crosses of wheat with alien species for Hessian fly resistance were carried out by H. Sharma in cooperation with Dr. Ouafae Benlhabib in Morocco.
Evaluation by ELISA of 56 El. elongata and six El. pontica accessions demonstrated that these were resistant to P-PAV and RPV BYDV isolates.
Preliminary studies of translocation lines derived from the BYDV-resistant P29 line have indicated that several of these lines contain multiple translocations that can be separated through crosses to susceptible wheat lines. Wheat lines that are resistant to BYDV and contain a minimal amount of wheatgrass DNA should be possible to obtain.
Facilitating the effort to incorporate BYDV resistance into elite material, a telomere repetitive sequence was identified that cosegregates with the wheatgrass-derived BYDV resistance. A rapid PCR-based test was developed as a marker-assisted selection tool for identifying BYDV resistant plants without the need for the standard virus inoculation and detection method.
I.M. Dweikat and H.W. Ohm.
We are in the process of constructing a BAC library in the A-genome progenitor T. urartu. The isolated high- molecular weight DNA was embedded in agarose microplugs. The plugs were digested with EcoRI plus EcoRI methylase at a ratio of 1:20. To date, we have available at least 30,000 clones that contain inserts ranging in sizefrom 50 to 230 kb, with an average of 110 kb. Our goal is to have at least 150,000 clones, giving us 3 X coverage of the diploid T. uartu genome.
Septoria leaf blotch.
We are continuing to analyze the genetics of the S. tritici blotch pathogen, Mycosphaerella graminicola. Previous work identified three RAPD loci with size-variable amplification products. Alleles at each locus were cloned and sequenced and, in each case, the polymorphism was due to a single deletion of 2060 base pairs. Primers were developed to amplify across the size-variable region at each locus, yielding SCAR markers for each locus. These markers can be used to characterize populations of M. graminicola in the field. To identify more markers, we are attempting to convert a DNA-fingerprint probe for M. graminicola (developed by Bruce McDonald) into SCAR-type markers. The goal is to develop a minimum of 810 SCAR markers for analyzing the population genetics and epidemiology of this organism.
More than 100 RAPD loci, including the SCAR markers, were placed onto a genetic map of M. graminicola prepared in a collaborative project with Gert Kema (Wageningen, The Netherlands). The final map will contain virulence, mating type, and over 300 AFLP markers developed by Dr. Kema plus our 100 RAPD and SCAR markers.
Crosses were made to determine whether various genes for resistance to Septoria tritici blotch in wheat are independent. F2 populations of the cultivar Sullivan (containing the Bulgaria 88 resistance gene) crossed with the cultivars IAS 20, Israel 493, and Veranapolis were tested with an Indiana isolate of the Septoria tritici blotch pathogen. There was no segregation in the 'IAS 20 / Sullivan' population, indicating that the genes may be allelic, linked, or identical. Susceptible plants were identified in the other populations, indicating that the resistance genes in Israel 493, Veranapolis, and Tadinia are independent from the gene in Bulgaria 88. Crosses between Israel 493 and Veranapolis and Israel 493 and IAS 20 also yielded susceptible progeny, indicating that these genes are independent from each other. However, the number of susceptible plants in the 'Israel 493 / IAS 20' population was smaller than expected. Additional tests are continuing during the spring greenhouse season.
Work with resistance gene analogs from wheat is continuing, and we have obtained genomic clones containing some of the resistance gene analogs. We are now preparing to map the resistance gene analogs to determine whether they are located near any known resistance genes.
Differential display is continuing to identify genes expressed in the resistant cultivar Tadinia in response to inoculation with M. graminicola. A number of clones has been obtained, one of which has some similarity to a pathogenesis-related protein from legumes. Work to obtain additional clones is continuing.
For more information see my lab web site at: http://www.btny.purdue.edu/USDA- ARS/Goodwin_lab/Goodwin_Lab.html.
D. Huber, D. Schulze, and I. Thompson.
Soilborne diseases continue to be important factors limiting the yield and quality of wheat in Indiana. Take-all research has focused on 1) the interaction of manganese oxidation as a virulence factor in G. graminis var. tritici, 2) the role of microorganisms in the rhizosphere that influence manganese availability, and 3) the critical role of manganese as a micronutrient in resistance and defense reactions of the wheat plant. Only isolates of G. graminis var. tritici, which change reduced manganese to the unavailable oxidized manganese (Mn^+2^ to Mn^+4^) are virulent onwheat. Isolates that are temperature sensitive for virulence show the same temperature sensitivity for manganese oxidation. Cultural practices and rhizosphere organisms that oxidize manganese can predispose wheat to take-all or increase the severity of take-all, and, conversely, organisms that reduce manganese can reduce the severity of take-all and function in biological control. Wheat cultivars efficient for micronutrient uptake are tolerant to take-all. We have confirmed these interacting effects during infection and pathogenesis by use of high energy X-ray fluorescence techniques at the National Synchrotron Light Source.
Potential biological control organisms are being evaluated against take-all using a standardized protocol as part of the Southern Regional Research Project on Biological Control. This research has demonstrated that formulation of the product may be as important in suppressing disease as any of the agents evaluated. Coöperative research with the Ningxia and Gansu Institutes of Plant Protection in Northwestern China on chemical, biological, and cultural controls of take-all has been conducted the past 4 years and is continuing. This coöperation has provided an opportunity to share ideas and materials for more effective control of take-all and other soilborne diseases.
Fusarium head blight.
G. Shaner and G. Buechley.
The resistance to scab in certain Chinese wheat varieties, which are being extensively used as sources of resistance for U.S. breeding programs, is thought to derive from Italian wheats. We searched the GRIN database for wheats, both winter and spring habits, originally collected from Italy.
Forty-two accessions were evaluated for FHB resistance. Selected progeny from a preliminary screening were evaluated in the greenhouse to confirm their resistance to F. graminearum. Plants were inoculated by spraying the entire spike with a spore suspension or by introducing a spore suspension into a central floret of each spike. These two inoculation methods were intended to detect different kinds of resistance (to initial infection or to spread of the fungus within a spike).
In the initial test, we observed a considerable range in scab severity among lines. The more striking result was the considerable variation in amount of FHB among plants within accessions, indicating considerable heterogeneity in resistance in the original germ plasm accessions. Progeny of 19 accessions from the preliminary test were selected for further evaluation in the autumn of 1997. Although the second test represented lines from plants that appeared to be resistant in the original test, there was still a wide range in severity of head blight, for both the floret and spray inoculations. The correlation between head blight severity for the parent plant and the mean severity for the five progeny plants subjected to spray inoculation was only 0.013. A similarly low correlation was noted when data for the point inoculation of progeny plants were analyzed.
Nonetheless, several of the lines in the second test had low mean ratings for head blight, and the effect of lines in the analysis of variance was highly significant. A poor correlation occurred between severity for the spray and floret inoculations. Several lines had low severity with both types of inoculation. This germ plasm appears to have different kinds of resistance and, therefore, different genes for resistance. The range in severity of head blight among the lines suggests that several genes for resistance may be represented in this material. Whether these genes differ from those in the Chinese material remains to be determined.
We also tested lines from a Uniform Winter Wheat Fusarium Head Blight Nursery, which includes lines from many wheat breeding programs in the eastern soft wheat region. Tests were conducted as described above for the Italian germ plasm. A weak correlation between heading date and severity of FHB was noted, with later-maturing wheats tending to be more resistant. Resistant lines were found among the early-maturing wheats. Differences among lines in severity of FHB were substantial, but most had less than the susceptible check varieties, indicating that wheat breeders are making progress in developing resistance to this disease. As noted in the Italian wheat study, a poor correlation occurred between severity of head blight following spray inoculation and following floret inoculation, suggesting that different types of resistance are represented in this germ plasm. A couple of lines were very resistant to floret inoculation (resistance to spread of the fungus in the spike following primary infection), butvery susceptible to spray inoculation (no resistance to primary infection).
Research on Hessian fly.
Insect surveys. Uniform Hessian Fly Nursery (Cambron and
Ratcliffe). Twenty-two Hessian fly- resistant
wheat cultivars or germ plasm lines were evaluated in Uniform
Hessian Fly Nursery Trials in Alabama (5),Arkansas (1), Georgia
(3), Illinois (1), Indiana (3), and South Carolina (2). Hessian
fly infestations were too low to provide meaningful data in 1998
in all but two trials in Alabama (Baldwin and Hale Counties) and
Georgia (Griffin and Plains). At these locations, wheat entries
carrying Hessian fly resistance genes H7H8, H9,
H12, H13, H17, H18, H21, and
H26 were the most effective, although H9 was less
effective in the trial at Plains than at the other locations.
Twenty-two wheat lines or cultivars from the Uniform Hessian Fly
Nursery, and 34 wheat lines each from the Uniform Southern and
Uniform Eastern Soft Red Winter Wheat Nurseries were evaluated
for responses to Hessian fly biotypes GP, B, C, D, E, and L in
laboratory tests. The response of wheat lines to the Hessian fly
biotypes will be published in 1999 in the USDA, ARS, Special Report
"Hessian Fly Status Report for Crop Year 1998/99", available
from S. Cambron.
Alabama (Ratcliffe in cooperation with K. Flanders, Auburn University). Hessian fly populations were collected from seven locations in Alabama in 1998. Results of biotype tests with these populations and three populations collected in 1997 demonstrated that frequencies of the highly virulent biotype L ranged from 016 % in southern counties (Baldwin, Henry, and Washington); 033 % in central counties (Elmore, Hale, and St. Clair); and 5077 % in northern counties (Lawrence, Madison, and Marshall). Wheat cultivars with H7H8 resistance should be effective against fly populations in central and southern Alabama as a result of the low to moderate level of biotype L in these areas. Data from the Uniform Hessian Fly Nursery Trials in Baldwin and Hale Counties, reported above, substantiated this conclusion.
Cultivar release (Cambron and Ratcliffe in cooperation with H. Ohm). The development and release of the soft winter wheat cultivar INW9811 in cooperation with Purdue University were significant steps in improving Hessian fly control for wheat growers in the southern mid-west and mid-south. INW9811 is the first wheat variety to contain the Hessian fly-resistance gene H13 and to demonstrate resistance to biotype L. INW9811 will be particularly useful to growers in southern IL and IN, northeastern AR, northern AL, GA, SC, and southern VA where present varieties are not effective because of the high frequency of Hessian fly biotype L in field populations.
Physiological parameters (Gumaelius and
Ratcliffe). Research was begun in
July, 1998, to investigate plant physiological responses in Hessian
fly-susceptible, resistant, and tolerant wheat when exposed to
biotype L at 18 and 26 C. Of particular interest are possible
changes associated with these responses by wheat plants that influence
chloroplast production, production and relative concentrations
of sugars, and cell structure. Physiological parameters were identified
and bioassay, chemical, and physiological methods were selected
for investigating the various parameters.
Hessian fly genetics (Shukle and Zantoko). The most cost-effective and environmentally sound method of control of the Hessian fly is through genetically resistant wheat. However, the use of resistant wheat has resulted in the development of biotypes of the insect that can overcome resistance. Our research is directed toward understanding the molecular basis of how the fly overcomes resistance as well as the development of molecular markers for analysis of the genetic structure of fly populations. This knowledge is essential for collaboration with wheat breeders to ensure effective and durable control of the Hessian fly. We have identified AFLP markers tightly linked to the locus controlling avirulence/virulence with respect to resistance gene H13 in wheat. These markers have been cloned and converted to SCAR markers. This approach is being undertaken with respect to loci controlling the interaction with other genes for resistance in wheat.
Molecular aspects of Hessian fly resistance (Williams, Collier, and Liang). Hessian fly crosses were constructed to determine whether virulence to the resistance gene H6 is due to the same gene in virulent populations from across the U.S. Individual Hessian flies from 10 H6-virulent populations were intercrossed in pair- wise combinations. Results indicated that all H6-virulent populations utilized the same virulence gene rather than accumulating mutations in a biosynthetic pathway leading to the production of an elicitor molecule. STS primers were designed as markers for a new resistance gene to aid in its introgression, along with other Hessian fly resistance genes, into a pyramided cultivar. We further characterized a wheat gene was that is induced soon after avirulent larvae begin feeding on seedlings. This gene is present in about one copy per genome and is similar in the DNA sequence to jasmonic acid-induced genes that may be involved in systemic acquired resistance.
Avirulence genes (J. Stuart). The gene-for-gene relationship between wheat and the Hessian fly wasinvestigated by molecular genetic mapping of three X-linked avirulence genes, vH6, vH9, and vH13, in the Hessian fly. These genes confer avirulence to Hessian fly-resistance genes H6, H9, and H13 in wheat. We used a combination of bulked segregant analysis and two- and three-point crosses to determine the order of these genes with respect to each other; the white eye mutation; and three X-linked molecular markers, G15-1, 020, and 021. These markers were developed from genomic lambda clones, G15-1, 020, and 021, which were previously positioned on the polytene chromosomes of the Hessian fly by in situ hybridization. Each avirulence gene was found to reside on chromosome X1, but they were not clustered. The gene order was determined to be vH9 - vH6 - G15 - 1 - w - vH13 - 020 - 021. The positions of lG15-1, l020, and l021 on the polytene chromosomes of the Hessian fly salivary gland established their orientation on Hessian fly chromosome X1. These results are the best evidence to date that single corresponding avirulence genes exist in the Hessian fly for each resistance gene in wheat.
Ted Kisha, Ph.D. degree from Michigan State
University, joined the Small Grains Research Team in March 1998,
in the position of Research Associate in the Department of Agronomy.
Ted will focus on genetics of resistance to glume blotch caused
by Phaeosphaeria nodorum. Ernie Cebert completed
the Ph.D. degree with H. Ohm and is on the faculty in the Department
of Plant and Soil Science at Alabama A & M University, Normal,
AL. Vanessa Cook completed the Ph.D. degree with H. Ohm and is
a maize breeder at DeKalb Genetics, Inc., Spencer, Iowa. Louis
Yang completed the Ph.D. degree with H. Ohm and is a maize breeder
at Asgrow Seed Company, 634 East Lincoln Way, Ames, IA. Xiaorong
Shen began studies toward the Ph.D. degree and Jim Uphaus began
studies toward the MS degree under the direction of H. Ohm.
Anderson JM, Bucholtz DL, Greene AE, Francki
MG, Gray SM, Sharma H, Ohm HW, and Perry KL. 1998. Characterization
of wheatgrass-derived barley yellow dwarf virus resistance in
a wheat alien chromosome substitution line. Phytopathology 88:851-855.
Anderson JD, Bucholtz D, Crasta O, Greene A, Francki M, Sharma H, and Ohm H. 1998. Effectiveness of wheatgrass-derived barley yellow dwarf virus resistance and identification of resistant translocation lines. 7th Intl. Congress Plant Path., Edinburgh, Scotland, UK.
Boukar O and Ohm HW. 1998. Relation between wheat flower opening and incidence of Fusarium head blight. Fusarium Head Blight Forum, E. Lansing, MI.
Bucholtz D, Anderson JM, Sharma HC, and Ohm HW. 1999. Molecular analysis of barley yellow dwarf virus resistant wheat translocation lines containing Thinopyrum intermedium chromosomal segments, San Diego, CA
Drake DR and Ohm HW. 1998. Scab resistance genes of wheat cultivar Ning 7840. Fusarium Head Blight Forum, E. Lansing, MI.
Dweikat I and Ohm H. 1998. Isolation of
resistance gene analogs in wheat. Plant Genome VI. San Diego,
El Bouhssini M, Benlhabib O, Bentika A, Sharma HC, and Lhaloui S. 1998. Sources of resistance in Triticum and Aegilops species to Hessian fly in Morocco. Arab J Plant Prot 15:126-128.
Fennimore SA, Nyquist WE, Shaner GE, Myers SP, and Foley ME. 1998. Temperatu