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Disease resistance. Wheat Stem Sawfly (WSS).

Solid stem locus

Contributed by Luther Talbert (usslt@montana.edu )

Background information

Wheat stem sawfly (Cephus cinctus Norton) is a major insect pest in areas of the Northern Great Plains (1). In the State of Montana alone it causes losses for $25 million dollars per year.

The female fly lays the eggs inside the stem and the damage to the wheat plant is caused by the larvae. Solid stems are more resistant to insect development than plants with hollow stems. For this reason, the use of wheat cultivars containing solid stems is the primary control measure. However, the environmental effects on the expression of this trait can be problematic, thus molecular markers are a valuable resource for solid stem breeding.

A doubled haploid (DH) winter wheat population derived from a 'Rampart' (PI 593889, solid stems) X ‘Jerry’ (hollow stems) cross was analyzed to identify molecular markers linked to genes controlling stem solidness. The DH population was genotyped using GWM and BARC microsatellite primers that spanned the wheat genome. Four microsatellite markers (Xgwm247, Xgwm340, Xgwm547, and Xbarc77) were found linked to a single solid stem QTL (designated Qss.msub-3BL) on chromosome 3BL. However Xgwm247, Xgwm340 and Xgwm547 were found to be more closely linked to the QTL than Xbarc77. Single marker analysis showed Qss.msub-3BL contributes at least 76% of the total variation for stem solidness. Additionally, no significant relationship existed between Qss.msub-3BL and other agronomic traits, including yield (2).

Methods

In the methods section you can find a protocol and expected products for Xgwm340

References

1. The wheat stem sawfly (Hymenoptera: Cephidae) revisited. Weiss MJ, Morrill WL. In: American Entomologist, 1992, 38: 241-245.

2. Identification of microsatellite markers associated with a stem solidness locus in wheat. Cook JP, Wichman DM, Martin JM, Bruckner PL., Talbert LE. In: Crop Science. In press. [abstract]

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