Virus Diseases of Cereal Crops in South Dakota

Virus diseases of wheat, oats and barley have been reported from various parts of the world during the last three decades. In some instances viruses have proven be the real causes diseases formerly attributed to other agents. The earliest reports of a virus disease of wheat concerned a mosaicrosette disease first observed in southeastern Illinois in 1919. The disease caused by a soil-borne virus was later found in a number of localities in the eastern half of the United States, but to date it has not been reported west of the Missouri River. However, other mosaic disease of wheat have been observed on wheat in California. Reports from foreign countries indicate the occurrence of soil-borne mosaics in Japan and Egypt, and a leafhopper-transmitted virus causing a mosaic of wheat in western Russia. The virus diseases reported on oats include a soil-borne mosaic of winter oats in Alabama and Carolinas, and a leafhopper-transmitted virus in Siberia. Barley has also been infected with certain viruses. False stripe, which has long been considered a non-parasitic disease of barley, was recently shown to be caused by a virus which is seedborne. In 1951 an aphid-transmitted disease of barley named “yellow dwarf” was discovered in California. In the fall of 1949 experimental work was begun on virus diseases affecting cereal crops in South Dakota. The diseases that have been studied so far include wheat streak mosaic , wheat striate mosaic, barley false stripe, and Agropyron streak mosaic. The results of investigations on the distribution, transmission and host range of these diseases are presented

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