A Dominant Gene for Resistance to Wheat Streak Mosaic Virus in Winter Wheat Line CO960293-2

Wheat streak mosaic (WSM), caused by Wheat streak mosaic virus (WSMV), is a devastating disease in wheat (Triticum aestivum L.) in the Great Plains of North America. Use of resistance is an effective and environmentally sound method to control the disease. In this study, six wheat genotypes were compared for their responses to WSMV infection under growth chamber conditions. The three resistant genotypes, KS96HW10-3 (Wsm1), Mace (Wsm1), and CO960293-2, had disease scores significantly lower than the remaining three genotypes without major resistance. Disease in TAM 111 and TAM 112 was consistently less severe than Karl 92. A population consisting of 188 F-2:3 families derived from the cross CO960293-2 x TAM 111 was used for determining inheritance of the WSMV resistance and for molecular mapping of the resistance in CO960293-2. Data on segregation of resistance indicated that the resistance in CO960293-2 is conditioned by a single dominant gene, which was named Wsm2. Transgressive segregation toward susceptibility occurred in the population suggesting a minor gene in the moderately susceptible parent TAM 111, which was not allelic to Wsm2. Wsm2 was mapped to the short arm of chromosome 3B with two flanking simple sequence repeat markers. The single dominant gene inheritance for WSMV resistance in CO960293-2 has been consistent with the observations that the resistance can be readily transferred to adapted cultivars.