Key message
Heterogeneous Lr34 genes for leaf rust in winter wheat cultivar ‘Duster’ and KASP markers for allelic variation in exon 11 and exon 22 of Lr34.
Wheat,
Triticum aestivum
(2
n
= 6
x
= 42, ...AABBDD), is a hexaploid species, and each of three homoeologous genomes A, B, and D should have one copy for a gene in its ancestral form if the gene has no duplication. Previously reported leaf rust resistance gene
Lr34
has one copy on the short arm of chromosome 7D in hexaploid wheat, and allelic variation in
Lr34
is in intron 4, exon 11, exon 12, or exon 22. In this study, we discovered that Oklahoma hard red winter wheat cultivar ‘Duster’ (PI 644,016) has two copies of the
Lr34
gene, the resistance allele
Lr34a
and the susceptibility allele
Lr34b
. Both
Lr34a
and
Lr34b
were mapped in the same linkage group on chromosome 7D in a doubled-haploid population generated from a cross between Duster and a winter wheat cultivar ‘Billings’ which carries the susceptibility allele
Lr34c
. A chromosomal fragment including
Lr34
and at least two neighboring genes on its proximal side but excluding genes on its distal side was duplicated in Duster. The Duster
Lr34ab
allele was associated with tip necrosis and increased resistance against leaf rust at adult plants in the Duster × Billings DH population tested in the field, demonstrating the function of the Duster
Lr34ab
allele in wheat. We have developed KASP markers for allelic variation in exon 11 and exon 22 of
Lr34
in wheat. These markers can be utilized to accelerate the selection of
Lr34
in wheat.
Lr34 in wheat is a non-race-specific gene that confers resistance against multiple fungal pathogens. The resistant allele Lr34 and the susceptible allele Lr34s can be distinguished by three ...polymorphisms that cause alternation of deduced amino acid sequences of Lr34 at the protein level. In seedlings of a cultivar carrying the resistant Lr34r allele, only a portion (35%) of its transcripts was correctly spliced and the majority (65%) of its transcripts were incorrectly spliced due to multiple mis-splicing events. Lr34 mis-splicing events were also observed at adult plant age when this gene exerts its function. All of the mis-spliced Lr34r cDNA transcripts observed in this study resulted in a premature stop codon due to a shift of the open reading frame; hence, the mis-spliced Lr34r cDNAs were deduced to encode incomplete proteins. Even if a cultivar has a functional Lr34 gene, its transcripts might not completely splice in a correct pattern. These findings suggested that the partial resistance conferred by a quantitative gene might be due to mis-splicing events in its transcripts; hence, the resistance of the gene could be increased by eliminating or mutating regulators that cause mis-splicing events in wheat.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Prevalence of tan spot of wheat caused by the fungus Pyrenophora tritici-repentis has become more prevalent in Oklahoma as no-till cultivation in wheat has increased. Hence, developing wheat ...varieties resistant to tan spot has been emphasized, and selecting pathogen isolates to screen for resistance to this disease is critical. Twelve isolates of P. tritici-repentis were used to inoculate 11 wheat cultivars in a greenhouse study in splitplot experiments. Virulence of isolates and cultivar resistance were measured in percent leaf area infection for all possible isolate x cultivar interactions. Isolates differed significantly (P < 0.01) in virulence on wheat cultivars, and cultivars differed significantly in disease reaction to isolates. Increased virulence of isolates detected increased variability in cultivar response (percent leaf area infection) (r = 0.56, P < 0.05) while increased susceptibility in cultivars detected increased variance in virulence of the isolates (r = 0.76, P < 0.01). A significant isolate × cultivar interaction indicated specificity between isolates and cultivars, however, cluster analysis indicated low to moderate physiological specialization. Similarity in wheat cultivars in response to pathogen isolates also was determined by cluster analysis. The use of diverse isolates of the fungus would facilitate evaluation of resistance in wheat cultivars to tan spot.
Prevalence of tan spot of wheat caused by the fungus Pyrenophora tritici-repentis has become more prevalent in Oklahoma as no-till cultivation in wheat has increased. Hence, developing wheat ...varieties resistant to tan spot has been emphasized, and selecting pathogen isolates to screen for resistance to this disease is critical. Twelve isolates of P. tritici-repentis were used to inoculate 11 wheat cultivars in a greenhouse study in splitplot experiments. Virulence of isolates and cultivar resistance were measured in percent leaf area infection for all possible isolate x cultivar interactions. Isolates differed significantly (P < 0.01) in virulence on wheat cultivars, and cultivars differed significantly in disease reaction to isolates. Increased virulence of isolates detected increased variability in cultivar response (percent leaf area infection) (r = 0.56, P < 0.05) while increased susceptibility in cultivars detected increased variance in virulence of the isolates (r = 0.76, P < 0.01). A significant isolate × cultivar interaction indicated specificity between isolates and cultivars, however, cluster analysis indicated low to moderate physiological specialization. Similarity in wheat cultivars in response to pathogen isolates also was determined by cluster analysis. The use of diverse isolates of the fungus would facilitate evaluation of resistance in wheat cultivars to tan spot.
Air-stable dinuclear complexes (bmsab)Ni
(tmsab)Ni
(bmsab)
and (bmsab)Zn
(tmsab)Zn
(bmsab)
(bmsab = bis(methanesulfoneamido)benzene, tmsab = tetra(methanesulfonamido)benzene) were prepared via a ...synthetic route based on heteroleptic precursor complexes. The new complexes combine a distorted tetrahedral coordination environment with an open-shell bridging ligand. The Zn
species was subjected to a detailed investigation of the (spectro-)electrochemical processes. The Ni
species is a rare example of a complex that combines strong exchange coupling (
> 440 cm
) with pronounced positive zero-field splitting (
= +72 cm
). Combining SQUID magnetometry and (HF)EPR spectroscopy with ab initio calculations allowed for accurate quantification of the exchange interaction.
Grain yields of winter wheat (Triticum aestivum L.) in the southern Great Plains are often reduced by the presence of foliar diseases. This study was conducted to determine whether the application of ...foliar fungicides is an economically optimal management strategy. The effects of fungicide treatment on commercially available hard red winter wheat varieties with differing levels of genetic resistance (i.e., resistant, intermediate, and susceptible) to foliar diseases were investigated at two locations, Apache and Lahoma, OK, USA, for the harvest years 2005–2012. Two fungicides were rotated between the two locations and applied at approximately Feekes growth stage 9–10.5. When averaged across years, plots to which fungicide was applied generated greater average net returns than plots that did not receive fungicide for susceptible varieties at Apache, and for resistant, intermediate, and susceptible varieties at Lahoma. However, foliar fungicide application was not economical in every year at either location suggesting fungicide use should be reassessed each year given that profitability depends on year specific yield potential, prices, and foliar disease conditions. At both locations high disease incidence occurred in all but one site-year when the average March through May relative humidity exceeded 65%. Additional research would be required to determine the relationship between weather, including relative humidity, and disease incidence, and to develop an economic threshold for treatment decision aid.
•Grain yield response of winter wheat to fungicide treatment was variable.•The economics of fungicide use varied within year across sites 170 km apart.•Fungicide use generated greater expected net returns for all varieties at one site.•At one site risk averse producers would have optimally treated resistant varieties.•Yield potential, treatment cost, wheat price, and disease conditions all matter.
Air-stable dinuclear complexes (bmsab)NiII(tmsab)NiII(bmsab)3– and (bmsab)ZnII(tmsab)ZnII(bmsab)3– (bmsab = bis(methanesulfoneamido)benzene, tmsab = tetra(methanesulfonamido)benzene) were ...prepared via a synthetic route based on heteroleptic precursor complexes. The new complexes combine a distorted tetrahedral coordination environment with an open-shell bridging ligand. The ZnII species was subjected to a detailed investigation of the (spectro-)electrochemical processes. The NiII species is a rare example of a complex that combines strong exchange coupling (J > 440 cm–1) with pronounced positive zero-field splitting (D = +72 cm–1). Combining SQUID magnetometry and (HF)EPR spectroscopy with ab initio calculations allowed for accurate quantification of the exchange interaction.
Powdery mildew significantly affects grain yield and end-use quality of winter wheat in the southern Great Plains. Employing resistance resources in locally adapted cultivars is the most effective ...means to control powdery mildew. Two types of powdery mildew resistance exist in wheat cultivars, i.e., qualitative and quantitative. Qualitative resistance is controlled by major genes, is race-specific, is not durable, and is effective in seedlings and in adult plants. Quantitative resistance is controlled by minor genes, is non-race-specific, is durable, and is predominantly effective in adult plants. In this study, we found that the segregation of powdery mildew resistance in a population of recombinant inbred lines developed from a cross between the susceptible cultivar Jagger and the resistant cultivar 2174 was controlled by a major QTL on the short arm of chromosome 1A and modified by four minor QTLs on chromosomes 1B, 3B, 4A, and 6D. The major QTL was mapped to the genomic region where the Pm3 gene resides. Using specific PCR markers for seven Pm3 alleles, 2174 was found to carry the Pm3a allele. Pm3a explained 61% of the total phenotypic variation in disease reaction observed among seedlings inoculated in the greenhouse and adult plants grown in the field and subjected to natural disease pressure. The resistant Pm3a allele was present among 4 of 31 cultivars currently being produced in the southern Great Plains. The genetic effects of several minor loci varied with different developmental stages and environments. Molecular markers associated with these genetic loci would facilitate incorporating genetic resistance to powdery mildew into improved winter wheat cultivars.
Background Hidradenitis suppurativa is a debilitating chronic disease primarily affecting intertriginous skin of the axillae, perineum, and inframammary regions. The pathogenesis of this inflammatory ...disease is still poorly understood. Recently, increased attention has been paid to the role of the immune system. Objective Since the interleukin 12 (IL-12)/T helper 1 (Th1) and the IL-23/Th17 pathways are believed to be crucially involved in the pathogenesis of multiple chronic inflammatory diseases, we investigated the expression and cellular source of IL-12, IL-23, and IL-17 in hidradenitis suppurativa. Methods Ten patients with hidradenitis suppurativa were included in the study. Tissue samples were obtained from lesional skin and compared with healthy skin as a control. Expression of IL-12, IL-23, and IL-17 was analyzed by semiquantitative real-time polymerase chain reaction and immunohistochemistry, and the cellular source of these cytokines was determined by double immunofluorescence. Results IL-12 and IL-23 were found to be abundantly expressed by macrophages infiltrating papillary and reticular dermis of lesional skin. In accordance with the high expression of IL-23 and its important role in the development of T helper 17 (Th17) cells, IL-17-producing T helper cells were found to distinctly infiltrate lesional dermis. Limitations The sample size was small. Conclusions Our findings suggest that the IL-23/Th17 pathway is expressed in hidradenitis suppurativa and further support involvement of the immune system. Moreover, targeting the IL-12/IL-23-common subunit p40 with novel monoclonal antibodies may represent a new option for the treatment of this recalcitrant disease.
Fungicides protect winter wheat (Triticum aestivum L.) yield potential by managing foliar fungal diseases, but little information comparing one vs. two applications is available for the US southern ...Great Plains. Field experiments conducted from 2016–2018 at two Oklahoma locations (Apache and Stillwater) used two winter wheat cultivars (‘Gallagher’ and ‘Bentley’) and four fungicide application timings (control, Feekes 6, Feekes 9, and Feekes 6 + 9). Disease levels were highest during 2017 due to leaf rust. Dry conditions during 2018 limited disease development overall. Fungicide applications resulted in significantly higher yields in three of eight year × location × cultivar comparisons, all during 2017. The Feekes 6 + 9 treatment only showed the highest grain yield for the leaf rust‐susceptible cultivar Bentley at Stillwater that season. Partial profit was also examined by year, location, and cultivar using four fungicide cost scenarios at three grain sale prices. Only 22 of 96 comparisons showed significant positive partial profit from fungicide use, and all occurred at Stillwater during 2017. Two fungicide applications had the highest profit in 4 of the 22 comparisons for the cultivar Bentley. However, a single application of a low‐cost fungicide was most often among the highest profitable fungicide treatments, depending when higher disease levels were present. Partial profits from one and two fungicide applications were not significant or significantly negative when disease levels were low. Knowledge of cultivar disease susceptibility and disease scouting need to be considered to economically justify one or two fungicide applications in Oklahoma winter wheat.
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