gm-wheat/report-3

Spring wheat with scab-resistance transgene was not scab-resistant and showed localized death of leaf tissue.

Manipulated Organism: Spring wheat (Triticum aestivum L.), cultivar Bobwhite.

Inserted Transgenes: PR-2 and PR-3 genes for the pathogenesis-related proteins, beta-1,3-glucanase and chitinase, respectively, derived from the scab-resistant wheat cultivar Sumai-3. The genes were fused to the maize ubiquitin promoter so that they would be expressed in all parts of the plant.

Goal: Make spring wheat resistant to scab (Fusarium, head blight), a major disease.

Intended Effect: Four of the twenty-four transgenic lines expressed either one or both of the transgenes; these four lines showed stable inheritance of the transgenes for up to four generations; one line (32A) showed reduced scab infection under greenhouse conditions.

Unintended Effects:

Transgene activity in twenty of the twenty-four transgenic lines (80%) shut down after the initial generation, apparently due to gene silencing.
None of the plants from the four transgene-expressing lines was resistant to scab infection under field conditions (including plants of Line 32A that showed reduced scab infection under greenhouse conditions).
Plants of Line 32A, which had the highest transgene expression, also suffered from a "lesion-mimic phenotype" in which the leaves developed necrotic (tissue death) spots during flower formation (booting).

Source: Anand, A., T. Zhou, H. N. Trick, B. S. Gill et al. (2003). "Greenhouse and Field Testing of Transgenic Wheat Plants Stably Expressing Genes for Thaumatin-like Protein, Chitinase and Glucanase against Fusarium graminearum," Journal of Experimental Biology vol. 54, pp. 1101-11.

Author Affiliations: Departments of Biochemistry and Plant Pathology, Kansas State University.

Funding: Kansas Wheat Commission and the U.S. Wheat and Barley Scab Initiative (partial).

Product Status: Not on the market as of 2008.

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Seth JordanAugust 27, 2020