Trichothecene toxin effects on barley callus and seedling growth

Fusarium head blight (FHB) has caused devastating losses to barley growers in ND, MN and SD since 1993. A major component of these losses has been the formation of protein synthesis inhibitor trichothecene toxins such as deox ynivalenol (DON) by the Fusarium species that cause FHB. Genetic transforma tion of barley with genes that chemically inactivate or transport the toxin s out of cells has potential for reducing DON levels. The ability to direct ly select for callus cells transformed with these genes would simplify prod uction of transgenic plants and avoid the introduction of a second selectab le gene. Differences in seedling germination and growth on medium containin g toxin would help identify transgenic plants expressing the antitoxin gene s. The objective of this study was to determine the effects of DON and the related toxin diacetoxyscirpenol (DAS) on barley callus growth and seedling germination, root and shoot growth. The effects of the toxins on callus gr owth were small. Although statistically significant differences were seen a t the higher toxin levels after eight weeks, the differences were not large enough for selection between toxin resistant and toxin susceptible calli. Neither toxin had an effect on seed germination. DON at 5 and 10 mg/L signi ficantly reduced root growth by day 7, and 10 mg/L significantly reduced sh oot growth by day 4. The effects of DAS were greater, with all toxin levels significantly reducing root growth by day 2 and shoot growth by day 4. The results indicate that DAS may be usable for screening progeny of transgeni c plants for expression and segregation of anti-toxin genes.