INDIANA
PURDUE UNIVERSITY
Departments of Agronomy, Entomology, and Botany and Plant Pathology, and the USDA-ARS, Purdue University, West Lafayette, IN 47907, USA.
J.M. Anderson (USDAARS), H.W. Ohm,
F.L. Patterson, H.C. Sharma, and J. Uphaus (Department of Agronomy);
G. Buechley, S. Goodwin (USDAARS), D. Huber, and G. Shaner,
and X.R. Xu (Department of Botany and Plant Pathology); R.H. Ratcliffe,
R. Shukle, C.E. Williams, S. Cambron, C. Collier (USDAARS),
and J. Stuart (Department of Entomology).
Indiana farmers harvested 153,800 hectares (380,000 acres) of wheat in 2001, down 25 % from 2000. Most of the reduction in wheat acreage was accounted for by increased soybean acreage. Wheat yield in Indiana averaged 4,437 kg/ha (66 bu/acre) in 2001, 202 kg/ha (3 bu/acre) below the average yield in 2000. Farmers have seeded an estimated 142,000 ha (350,000 acres) of winter wheat in Indiana for the 2002 harvest season. Despite a steady decline in wheat production in Indiana, there are farmers who maintain an interest in producing high yields of high quality SRWW. Other farmers grow wheat because of a market for the straw. Livestock producers may grow wheat to provide land where animal manure can be spread during the summer. In the southern half of Indiana, double cropping with soybeans continues to be profitable.
Three new SRWW cultivars named INW0101,
INW0102, and INW0123, were licensed in 2001 for
marketing. INW0101 and INW0102 are early, similar to the cultivar
Clark, and should fit into a double-cropping system with soybeans.
INW0123 is similar in maturity to Patterson. All three cultivars
have Lr37, Sr38, and Yr17 and resistance
to local populations in Indiana of B. graminis. They also
have resistance to St. nodorum, S. tritici, and
WSBMV.
Diseases were not a serious problem in most Indiana wheat fields during 2001. The variable rainfall pattern throughout the state resulted in moderately severe leaf blotch in some areas but very little in others. Very little FHB, except in some local situations where wheat was planted into corn residue, but even there the incidence of was low. Stripe rust (yellow rust) was in several fields but was not severe. This rust usually is not seen in Indiana. Although weather in the spring seemed conducive to development of symptoms of infection by WSBMV or WSSMV, there was very little indication of either. The dry autumn of 2000 may have limited infection.
Fusarium head blight resistance sources (Shaner and Buechley). We have evaluated and reselected several wheat accessions for resistance to F. graminearum. We now have lines from the following accessions with a high degree and consistent expression of type-II resistance: Chokwang, CIMMYT 211, Futai 8944, Funo, Mentana, Paula VZ 434, and Oscar VY 5418
We crossed these resistant selections to susceptible cultivars (Sumai 3 or Ning 7840) and each other. We evaluated type-II resistance by inoculating a floret in the uppermost, well-developed spikelet of each plant when it was beginning to shed pollen. A 15-m droplet of spore suspension (104 conidia/ml) was used as inoculum. The inoculated spike was covered with a small, clear polyethylene bag for 48 h to provide moisture for infection. Blighted spikelets were counted 10 and 20 days after inoculation.
Based on this preliminary observation, genes for resistance in Mentana and Paula VZ 434 may differ from those in Sumai 3. CIMMYT 211, Futai 8944, and Y5418 probably share at least one resistance gene with Sumai 3. Several of these selections show a high degree of type-I and type-II resistance, but Victor V does not. When inoculated by the single-floret method, it is very resistant, but when the head is sprayed with a spore suspension, it is very susceptible.
Genes for resistance do not appear to be completely dominant. For example, when the F1 of 'Futai 8944/Norm' was backcrossed to Futai 8944, progeny ranged from highly resistant to moderately susceptible. Likewise, when the F1 of 'Futai 8944/Paula VZ 434' was backcrossed to Futai 8944, progeny ranged from highly resistant to moderately susceptible. When the F1 of 'Futai 8944/Sumai 3' (or Ning 7840) was backcrossed to Futai 3, all progeny were resistant or moderately resistant, further suggesting that Futai 8944 has one or more genes in common with Sumai 3.
Distributions of the backcross of a 'Chokwang/Clark' F1 to Clark and of the test cross of 'Chokwang/Clark' to Norm were trimodal. None of the progeny of the backcross to Chokwang were fully susceptible, but 62 % fell into an intermediate category.
Fungicides (Shaner and Buechley). We conducted fungicide trials at two locations in Indiana during 2001. The previous crop was corn at each location. Fungicides were applied prior to heading (Feekes 8 or 9) or during flowering (10.51 or 10.52). Stagonospora leaf blotch was the only foliar disease that developed at either location. Several fungicides reduced severity of leaf blotch compared to the untreated control, but two biological materials were ineffective. No scab developed at the north central location. Incidence of scab was low at SEPAC, but there were significant differences among treatments. No treatment had less head blight or number of scabby kernels in harvested grain than seen in the untreated control. Two treatments applied at flowering (Folicur and AMS 21619) did reduce DON contamination compared to the untreated control. Highly significant correlations between incidence of head blight in the field and number of scabby kernels (R = 0.87) and DON level (R = 0.87), and between number of scabby kernels and DON level (R = 0.90) were found.
Fusarium head blight resistance QTL (Drake and Ohm). RILs were developed by SSD, tested in the field and greenhouse by single floret inoculation at anthesis with F. graminearum, and genotyped with SSR markers. Two different QTLs on chromosome 3B were identified in the RILs developed from crosses of a susceptible backcross (BC3F5-derived) line (L1) by two resistant backcross (BC3F5-derived) lines (L1/L3 and L1/ L4) of FHB-resistant Chinese cultivar Ning 7840 and FHB-susceptible cultivar Clark (recurrent parent). Each population had a single unique QTL. Two QTLs, one near the centromere on chromosome 3B and another on chromosome 2B, were identified in a recombinant inbred population of FHB-resistant cultivar Freedom by the susceptible backcross derived line (L1). A single QTL on near the centromere of chromosome 3B, different than QFhs.ndsu-3B, was identified in a RIL population of the susceptible line L1 by FHB-resistant cultivar Patton.
Septoria tritici (Goodwin). Current activities include the analysis of transposition events of a transposable element Dr. Goodwin discovered in the genome of the S. tritici leaf blotch pathogen of wheat, M. graminicola, revealed evidence for repeat-induced point mutation (RIP). This phenomenon had not been seen previously in relatives of M. graminicola and can explain the inactivation of active transposable elements. In other fungi, RIP causes point mutations in duplicated DNA sequences which can affect gene function by introducing stop codons in open reading frames. RIP is well studied in Neurospora, but was not known to occur in Mycosphaerella or other species in the same order. Occurrence of RIP could explain the inactivation of transposable elements and could provide a means for the fungus to protect itself from introduced DNA.
Analyses of the mating-type genes from the barley speckled leaf blotch pathogen, Septoria passerinii, identified two ideomorphs. Each ideomorph contained an uninterrupted open reading frame for one of the two mating-type genes. Both mating types occurred together on the same leaves in North Dakota, and every isolate tested had a unique genotype for molecular markers. Therefore, it seems highly likely that the mating-type genes are functional and that this pathogen has a sexual stage in nature that might complicate efforts to manage the disease. The mating-type genes of S. passerinii and M. graminicola appear to be evolving extremely rapidly, about ten times faster than the ITS region of the ribosomal DNA. This rapid evolution of mating types may facilitate the speciation process of cereal pathogens.
Phylogenetic analyses of the ITS and 18S regions of the ribosomal DNA from the barley scald pathogen Rhynchosporium secalis revealed that this fungus is closely related to Tapesia yallundae, the eyespot pathogen of wheat, and also is related to Pyrenopeziza brassicae, the cause of light leaf spot of Brassica species. Previously, the phylogenetic relationships of R. secalis were not known. From this, we predict that the sexual stage of R. secalis, if it exists, should be a small (1-2 mm), cup-shaped structure produced on dead stubble following periods of rainfall from 1-10 months after harvest. Anyone walking through old barley stubble following a rain should keep their eyes open for the possible sexual stage of R. secalis.
In wheat, we have identified four AFLP markers linked to the Stb4 gene for resistance in the cultivar Tadinia. Work to convert those markers into a more useful form and to find the map location of the gene is continuing. Analysis of DH populations segregating for the Stb2 and Stb3 resistance genes received from Dr. Hugh Wallwork (South Australia) revealed an unknown gene in the Australian parent and two-gene segregations. Work on those populations is continuing and we expect to begin bulked-segregant analysis later this spring.
For more information see the Goodwin lab web site at: http://www.btny.purdue.edu/USDA-ARS/Goodwin_lab/Goodwin_Lab.html , and the USDAARS/Purdue University wheat genomics web site: http://www.btny.purdue.edu/usda-ars/wheatgen/ .
Biotype determination (Ratcliffe and Cambron). Hessian fly populations from Alabama, Illinois, Louisiana, Maryland, Mississippi, North Carolina, and Virginia were collected and biotyped in 2000-01. This was the first report of the Hessian fly from Louisiana and westcentral North Carolina. Biotype L was predominant (60-92 %) in all populations. The eastern Illinois samples were the first collected since the mid 1980s and substantiated that biotype L remains predominate in populations in this area of the state. Data from the central Alabama population indicates that the frequency of biotype L may be increasing in the southern two-thirds of the state. The high frequency of biotype L in the Louisiana and Mississippi populations may have resulted from movement of virulent biotypes into these areas via human activities (infested straw from areas where virulent biotypes are present) rather than from selection associated with exposure to resistance genes, since Hessian fly-resistant cultivars have not been deployed in these areas. Collections also were obtained from a single location in each state and may not be representative of populations throughout the area.
Evaluation of durum wheat genotypes for Hessian fly resistance (Ratcliffe, Ohm, Patterson, and Cambron). Twenty-six durum wheat genotypes were evaluated for resistance to Hessian fly biotypes D or L and four populations from the eastern U.S. soft winter wheat region. Resistance to laboratory biotypes D or L of the 26 genotypes was conditioned by one, two, or three genes, depending upon the line. Twenty-five of the genotypes were resistant to Hessian fly populations from the mid Atlantic and southeastern U.S.
Effectiveness of H9 and H13 resistance (Ratcliffe, Ohm, and Patterson). Elite wheat germ plasm lines or cultivars from the Purdue breeding program carrying H9 and/or H13 resistance to laboratory Hessian fly biotype L, were tested against fly populations collected in Alabama, Louisiana, Maryland, Mississippi, North Carolina, and Virginia in 2000 or 2001. The six fly populations ranged from 60-89 % biotype L based on laboratory biotype tests. The level of virulence in flies to genes H9 and H13 was similar for the six populations and highest in flies collected from central Alabama and northeastern Louisiana. Thirty to forty percent of the plants with H9 and H13 resistance genes were susceptible to the Alabama and Louisiana populations. The H9 and H13 sources were moderately to highly resistant to fly populations from Maryland, Mississippi, North Carolina, and Virginia. The samples collected from Alabama and Louisiana were limited to a very restricted area, therefore, results may not be representative of fly populations throughout these areas, and further studies will be required to ascertain the level of virulence to H9 and H13 in the southeastern U.S.
Expression of gene Hfr-1 in response to attempted feeding by Hessian fly larvae (Williams, Meyer, Collier, and Sardesai). Although plant responses to microbial attack can be categorized according to induction of various defense-response pathways, little information is available about genes induced by herbivorous insects. We have identified a novel plant gene that responds to an incompatible interaction with an insect with a specific avirulence allele. The expression of Hfr-1, a low-copy gene, increases rapidly in response to attempted feeding by avirulent first-instar larvae. After cloning and sequencing, we determined that the gene encodes a protein related to defense-response genes and lectins, suggesting possible involvement in plant defense against insects.
We demonstrated that the Hfr-1 gene responds specifically to Hessian fly and not to more generalized plant stress. This gene is unresponsive to desiccation and wounding and also is unaffected by inducers of certain defense-response pathways (methyl jasmonate and ABA). However, the gene is induced by salicylic acid and its analog BTH, which both induce systemic acquired resistance genes in several plant genera. In leaf blades, the Hfr-1 gene is induced to the same level independent of the number of larvae per plant. Although the gene is systemically induced (up-regulated in leaves) during an incompatible interaction, induction levels are higher at the base of the plant in tissues surrounding the larval feeding sites. The Hfr-1 gene was genetically mapped in the wheat genome and a second copy was identified. These map to loci Xupw1(Hfr1)-4A and Xupw1(Hfr1)-7D, respectively. Forty other partial cDNAs have been cloned that correspond to genes that respond to larval feeding. These sequences are currently under analysis.
Molecular biology of Hessian fly (Shukle, Yoshiyama, and Johnson). The primary focus of our laboratory is to obtain basic information that will expand the use of genetic resistance for control of Hessian fly. Specific objectives directed toward understanding Hessian fly genomics include developing genetic transformation to enhance molecular analysis through transposon tagging, enhancer trapping and gene validation; evaluating variation in mitochondrial and nuclear DNA sequences to reveal historical events, biogeographic patterns, population structure, and evolution of virulence; determining the structure and cytological location of cloned genes; and identifying transgenes to enhance resistance in wheat.
Recent results toward development of genetic transformation include use of microinjection for delivery of DNA into Hessian fly embryos and recovery of G1 individuals expressing the marker gene EGFP. Analysis of mtDNA sequence variation has revealed geographic patterns for mitochondrial haplotypes of Hessian fly in the U.S. and Canada. Analysis of additional populations from the Middle East, North Africa, and Europe will reveal information concerning historical events, biogeographical patterns, insight into population structure, and possible variation in selection pressures during dispersal and evolution of the fly in the Old World. A putative white gene has been cloned and characterized from Hessian fly. A white locus in Hessian fly is linked to three loci controlling virulence to resistance in wheat. Revealing the cytological location of the white gene will provide a chromosome landing for three loci controlling virulence. Efforts are being undertaken currently to develop collaboration for transformation of wheat with a putative transgene for resistance to Hessian fly to assess its biological activity.
Barley yellow dwarf virus resistance (Anderson, Sharma, and Ohm). Based on field trials of wheat lines containing group-7 Th. intermedium translocations, a translocation line, P98134, is being released as a SRWW germ plasm for BYDV/CYDV resistance. The line was derived from P29, a 7E(7D) chromosome substitution line.
Two BYDV-resistant addition lines with either a Th. intermedium group-1 or group-2 chromosome pair were previously crossed to the cultivar Patterson, and the seed irradiated with gamma rays. M5 families with potential translocations induced from wheatgrass group-1 and -2 chromosomes that have additional resistance to BYDV were identified. These lines were screened cytologically to exclude families containing whole alien chromosome and to select those with 2n = 42 chromosomes and resistance to BYDV for further characterization and crossing to pyramid BYDV resistance. Molecular markers are being identified and utilized to determine if these lines do contain translocations and if so the size of the translocation.
Wheat Hybrids (Uphaus and Ohm). High-yielding, wheat parental lines can produce
high-yielding wheat hybrids. However, heterosis in wheat is not
reliably predictable based only on genetic unrelatedness of the
parent lines. Effects of parental differences for yield components
of kernel weight, number of kernels/spike, and number of spikes/meter
row on grain yield heterosis were investigated. Eighteen single-cross
hybrids were produced from combinations of 11 wheat cultivars
and inbred lines contrasting for yield components. A CHA was
used to sterilize the seed parents for hybrid seed production
in 1998, at Lafayette, IN. Parents and hybrids were grown in
replicated performance trials in two seasons, 1999 and 2000, at
three locations in Indiana. Heterosis for grain yield, kernel
weight, number of kernels/spike, number of spikes/meter row, plant
height, heading date, straw strength, and seedling emergence were
evaluated. Analysis of variance was performed within years and
locations for each hybrid and its parents, hybrid compared to
the mid-parent value, and for all parents and hybrids combined.
AFLP markers were used to estimate the relatedness of the parental
lines. High-parent grain yield heterosis ranged from -12.3 to
10.9 % and mid-parent heterosis ranged from -10.4 to 13.7 %.
The highest yielding hybrids resulted from combinations of the
highest yielding parent lines. Hybrids from genetically diverse
parents with contrasting yield components were more likely to
be heterotic for grain yield.
Mehrdad Abassi finished a nine-month stay in Dr. Goodwin's laboratory studying the phylogenetics of rust fungi from wild grasses and other hosts in Iran, and returned home during July 2001. Dr. Tika Adhikari began a postdoctoral appointment in Dr. Goodwin's lab during March 2001. He will be working to identify molecular markers linked to the major genes for resistance to S. tritici leaf blotch and to look at the genomics of pest resistance in wheat. Jill Breeden joined the Goodwin lab as a Biological Science Research Technician during December 2001 and will run the greenhouse disease-screening project. Marcelo Giovanini, from Brazil, South America, initiated studies for the Ph.D. degree in Ohm's lab and will study the inheritance and mapping of resistance to Hessian fly from source lines PI134942 and PI192738. Jim Uphaus completed the M.S. degree and accepted the Small Grains Research Agronomist position in the Department of Agronomy.