Virus resistance. Wheat Streak Mosaic Virus (WSMV)
1. Identification of alien chromatin specifying resistance to wheat streak mosaic and greenbug in wheat germ plasm by C-banding and in situ hybridization. Friebe, B; Mukai, Y; Dhaliwal, H S; Martin, T J; Gill, B S In: Theoretical and Applied Genetics, 1991. 81(3):381-389
The chromosome constitutions of eight wheat streak mosaic virus (WSMV)-resistant lines, three of which are also greenbug (Schizaphis graminum) resistant, derived from wheat/Agropyron intermedium/ Aegilops speltoides crosses were analyzed by C-banding and in situ hybridization. All lines could be traced back to CI15092 in which chromosome 4A is substituted for by an Ag. intermedium chromosome designated 4Ai-2, and the derived lines carry either 4Ai-2 or a part of it. Two (CI17881, CI17886) were 4Ai-2 addition lines. CI17882 and CI17885 were 4Ai-2(4D) substitution lines. CI17883 was a translocation substitution line with a pair of 6AL.4AI-2S and a pair of 6AS.4Ai-2L chromosomes substituting for chromosome pairs 4D and 6A of wheat. CI17884 carried a 4DL.4AI-2S translocation which substituted for chromosome 4D. CI17766 carried a 4AL.4Ai-2S translocation substituting for chromosome 4A. The results show that the 4Ai-2 chromosome is related to homoeologous group 4 and that the resistance gene(s) against WSMV is located on the short arm of 4Ai-2. In addition, CI17882, CI17884, and CI17885 contained Ae. speltoides chromosome 7S substituting for chromosome 7A of wheat. The greenbug resistance gene Gb5 was located on chromosome 7S.
2. Registration of KS93WGRC27 wheat streak mosaic virus resistant T4DL.4Ai#2S wheat germplasm Gill, B. S.; Friebe, B.; Wilson, D. L.; Martin, T. J.; Cox, T. S. In: Crop Science, 1995. 35(4):1236-1237
3. Development of PCR markers linked to resistance to wheat streak mosaic virus in wheat. Talbert, L. E.; Bruckner, P. L.; Smith, L. Y.; Sears, R.; Martin, T. J. In: Theoretical and Applied Genetics, 1996. 93 (3):463-467
Wheat streak mosaic virus (WSMV), vectored by the wheat curl mite (Acer tulipae), is an important disease of wheat (Triticum aestivum L.) in the North American Great Plains. Resistant varieties have not been developed for two primary reasons. First, useful sources of resistance have not been available, and second, field screening for virus resistance is laborious and beyond the scope of most breeding programs. The first problem may have been overcome by the development of resistance to both the mite and the virus by the introgression of resistance genes from wild relatives of wheat. To help address the second problem, we have developed polymerase chain reaction (PCR) markers linked to the WSMV resistance gene Wsm1. Wsm1 is contained on a translocated segment from Agropyron intermedium. One sequence-tagged-site (STS) primer set (WG232) and one RAPD marker were found to be linked to the translocation containing Wsm1. The diagnostic RAPD band was cloned and sequenced to allow the design of specific PCR primers. The PCR primers should be useful for transferring Wsm1 into locally adapted cultivars
4. Field Evaluation of Transgenic and Classical Sources of Wheat streak mosaic virus Resistance. G. L. Sharp, J. M. Martin, S. P. Lanning, N. K. Blake, C. W. Brey, E. Sivamani, R. Qu, and L. E. Talbert In: Crop Science, 2002. 42(1):105-110
The development of wheat (Triticum aestivum L.) cultivars that are resistant to Wheat streak mosaic virus (WSMV), yet competitive in yield under nondiseased conditions, is an objective for breeding programs in the Great Plains. This field study was conducted to compare classical and transgenic sources of resistance to WSMV. Three sets of germplasm were evaluated. These included adapted cultivars with various levels of tolerance, transgenic wheat lines containing viral coat protein or replicase sequences from WSMV that showed resistance in greenhouse trials, and germplasm with resistance to WSMV due to a translocated segment of chromosome 4Ai-2 from Thinopyrum intermedium (Host) Barkworth and Dewey containing Wsm1. A replicated field trial was conducted at Bozeman, MT, over a two-year period to evaluate the effectiveness of these different sources of resistance to mechanical inoculation of WSMV. Adapted cultivars differed in their ability to tolerate WSMV with mean reductions in yield over the two years ranging from 41 to 74%. Incorporation of the replicase or coat protein gene from WSMV did not provide field resistance to viral infection and in general, transgenic lines yielded less than their parent cultivar, ‘Hi-Line’. Wheat-Thinopyrum lines positive for a DNA marker linked to the Wsm1 gene had significantly reduced yield losses ranging from 5 to 39% compared with yield losses of 57 to 88% in near isogenic lines not having the Wsm1 gene. Yield of lines with Wsm1 in the absence of disease ranged from 11 to 28% less than yield of lines without Wsm1. Our results suggest Wsm1 provides the best source of WSMV resistance but a yield penalty may exist because of the presence of the translocation.
5. Agronomic and End-Use Qualities of Wheat streak mosaic virus Resistant Spring Wheat. G. J. Baley, L. E. Talbert, J. M. Martin, M. J. Young, D. K. Habernicht, G. D. Kushnak, J. E. Berg, S. P. Lanning, and P. L. Bruckner In: Crop Science, 2001. 41(6):1779-1784
Development of wheat (Triticum aestivum L.) cultivars resistant to Wheat streak mosaic virus (WSMV) that remain productive in the absence of the disease would benefit wheat growers. A wheat germplasm (KS93WGRC27) carrying a Thinopyrum intermedium (Host) Barkworth and Dewey chromosome 4Js translocation conferring WSMV resistance was used to develop spring wheat populations segregating for WSMV resistance. Four populations, consisting of a total of 22 translocation-positive (WSMV-resistant), 36 translocation-negative (WSMV-susceptible), and eight parental lines, were grown as a randomized complete block with three replications at Bozeman and Conrad, MT, in 1998 and 1999. Treatments were arranged as a split plot with populations as main plots and progeny and parents as subplots. The agronomic performance of resistant and susceptible lines was compared under inoculated and noninoculated conditions to assess the effectiveness of the WSMV resistance gene and to determine the effects of the Thinopyrum translocation in the absence of disease. A small but significant decrease in yield was observed for noninoculated resistant lines in contrast to susceptible lines. However, the yield range of resistant entries suggests that the recovery of parental yield was possible. The resistance source was highly effective in limiting virus accumulation and yield losses to WSMV, resulting in only a 5% yield reduction in resistant lines under inoculated conditions compared with 32% for susceptible lines. In all instances where WSMV was introduced to field trials, the Thinopyrum translocation provided a significant benefit for resistant lines when compared with susceptible lines. The T. intermedium translocation present in resistant lines had no detrimental effects on end-use quality or other agronomic traits.