Comparison of Fusarium head blight resistance in cytoplasmic male sterile, maintainer and restorer lines in winter wheat

Fusarium head blight (FHB, caused by Fusarium graminearum) is a severe disease which threatens the yield and quality of harvested grain products, and hence causes major economic losses in wheat (Triticum spp.) and other small grain cereals. One of the infection routes for the pathogen is believed to be through the extruded anther. In order to study the role of the anther on FHB infection, FHB resistance was measured among wheat (Triticum aestivum L.) cultivars with non-extruded infertile anthers in cytoplasmic male sterile (CMS) lines and with extruded fertile anthers in their alloplasmic maintainer lines, and in an unrelated restorer line. We artificially inoculated the lines with F. graminearum (isolate NE 90) at 1.0 × 105 or 2.0 × 105 spores mL−1 for 72 or 96 hours. The results indicated that CMS cultivars were significantly more resistant than the maintainer and restorer cultivars. As the CMS lines differed from the maintainer lines by cytoplasm, anther health, anther extrusion, and seed set, additional experiments are needed to determine the role of each factor in infection. However, this research indicates that fertile anthers most likely are an important part of the infection pathway and of susceptibility to FHB

Impact of timing and method of virus inoculation on the severity of wheat streak mosaic disease

Open Access Article; Published Online: 23 Jan 2018Wheat streak mosaic virus (WSMV), transmitted by the wheat curl mite Aceria tosichella, frequently causes significant yield loss in winter wheat throughout the Great Plains of the United States. A field study was conducted in the 2013–14 and 2014–15 growing seasons to compare the impact of timing of WSMV inoculation (early fall, late fall, or early spring) and method of inoculation (mite or mechanical) on susceptibility of winter wheat cultivars Mace (resistant) and Overland (susceptible). Relative chlorophyll content, WSMV incidence, and yield components were determined. The greatest WSMV infection occurred for Overland, with the early fall inoculations resulting in the highest WSMV infection rate (up to 97%) and the greatest yield reductions relative to the control (up to 94%). In contrast, inoculation of Mace resulted in low WSMV incidence (1 to 28.3%). The findings from this study indicate that both method of inoculation and wheat cultivar influenced severity of wheat streak mosaic; however, timing of inoculation also had a dramatic influence on disease. In addition, mite inoculation provided much more consistent infection rates and is considered a more realistic method of inoculation to measure disease impact on wheat cultivars

Development of Single Nucleotide Polymorphism Markers for the Wheat Curl Mite Resistance Gene Cmc4

Wheat curl mite (Aceria tosichella Keifer) is an important wheat (Triticum aestivum L. em. Thell.) pest in many wheat-growing regions worldwide. Mite feeding damage not only directly affects wheat yield, but A. tosichella also transmits Wheat streak mosaic virus (WSMV). Wheat resistance to A. tosichella, therefore, helps control WSMV. OK05312 (PI 670019) is an advanced breeding line released from Oklahoma that shows a high level of A. tosichella resistance. To map the gene(s) conditioning wheat resistance to A. tosichella in OK05312, a genetic linkage map was constructed using single nucleotide polymorphism (SNP) markers derived from genotyping-by-sequencing (GBS) and a population of 186 recombinant inbred lines (RILs) from the cross ‘Jerry’ (PI 632433)/OK05312. Seedlings of both parents and the RIL population were infested by A. tosichella Biotype 1 in greenhouse experiments. One major quantitative trait locus was identified on the short arm of chromosome 6D, which corresponds to the previously reported gene Cmc4 for A. tosichella resistance. This gene explained up to 71% of the phenotypic variation and was delimited in a 1.7-Mb (?3.3-cM) region by SNPs 370SNP7523 and 370SNP1639. We successfully converted 12 GBS-SNPs into Kompetitive allele specific polymerase chain reaction (KASP) markers. Two of them tightly linked to Cmc4 were validated to be highly diagnostic in a US winter wheat population and can be used for marker-assisted breeding for incorporation of Cmc4 into new wheat cultivars